Lawn Boy mower with Tecumseh 4-stroke-cycle vertical shaft engine. Primer
bulb, non-adjustable carb.

I've been repairing / tinkering on mowers and other power equipment engines
since I was 10; not an expert by any means but some level of experience.
This has me stumped.

The engine seemed to have carb issues. It would take many pushes off the
primer bulb to get it to start. Sometimes I would take off the air cleaner
and shoot some gas from a spray bottle right into the barrel and then it
would start easily at least for a few seconds and in some cases continue to
run successfully and sometimes not. I once cut part of the lawn with a
paper towel wadded into the carb to partly choke it to get the mix okay.

So I dismantled the carb for cleaning and afterwards it was a better but
still not totally right. I was looking online for a carb rebuild kit when
I saw I could buy the entire carb--or a knockoff--for like twelve bucks. I
installed it and the engine ran well. They've dumbed the design down to
where there is no more actual speed control...you bend a tab that controls
governor speed tension. I did that; even used a strobe to check speed.

Used it a number of times and it was fine.

Now I cannot even get it to try to start.

My old trick of shooting in some gas did get a few partial starts but now
nothing.

So...no spark or no gas, right? Shooting in some gas manually would
eliminate that possibility.

So no spark?

I took it into a dark area and with the plug off but wire still hooked up
and the plug grounded with a clip lead I could see a spark when I cranked
the engine. I replaced the plug -- new last year -- anyway. No change.

Shooting in some gas as described does put out tiny puffs of smoke when I
crank, puffs that are not there with the plug disconnected. But nothing
like a true partial start. No sound other than what I make by pulling it.

I started to think there is something really unusual going on. Like a
valve stuck open or something. Nope...I pulled the head and they appear to
be working fine.

The only thing I can think of is that the spark is too weak. Or that the
new carb is so bad that the mix is so rich that there is no way to light it
off.

Before, grasping at straws and buying a new, potentially unnecessary,
magneto, I think maybe I will try to give the old carb a good cleaning and
put it back on.

On Monday, November 20, 2017 at 9:57:54 PM UTC-5, Steve Kraus wrote:
Lawn Boy mower with Tecumseh 4-stroke-cycle vertical shaft engine. Primer
bulb, non-adjustable carb.

I've been repairing / tinkering on mowers and other power equipment engines
since I was 10; not an expert by any means but some level of experience.
This has me stumped.

The engine seemed to have carb issues. It would take many pushes off the
primer bulb to get it to start. Sometimes I would take off the air cleaner
and shoot some gas from a spray bottle right into the barrel and then it
would start easily at least for a few seconds and in some cases continue to
run successfully and sometimes not. I once cut part of the lawn with a
paper towel wadded into the carb to partly choke it to get the mix okay.

So I dismantled the carb for cleaning and afterwards it was a better but
still not totally right. I was looking online for a carb rebuild kit when
I saw I could buy the entire carb--or a knockoff--for like twelve bucks. I
installed it and the engine ran well. They've dumbed the design down to
where there is no more actual speed control...you bend a tab that controls
governor speed tension. I did that; even used a strobe to check speed.

Used it a number of times and it was fine.

Now I cannot even get it to try to start.

My old trick of shooting in some gas did get a few partial starts but now
nothing.

So...no spark or no gas, right? Shooting in some gas manually would
eliminate that possibility.

So no spark?

I took it into a dark area and with the plug off but wire still hooked up
and the plug grounded with a clip lead I could see a spark when I cranked
the engine. I replaced the plug -- new last year -- anyway. No change.

Shooting in some gas as described does put out tiny puffs of smoke when I
crank, puffs that are not there with the plug disconnected. But nothing
like a true partial start. No sound other than what I make by pulling it..

I started to think there is something really unusual going on. Like a
valve stuck open or something. Nope...I pulled the head and they appear to
be working fine.

The only thing I can think of is that the spark is too weak. Or that the
new carb is so bad that the mix is so rich that there is no way to light it
off.

Before, grasping at straws and buying a new, potentially unnecessary,
magneto, I think maybe I will try to give the old carb a good cleaning and
put it back on.

If the theory is that it's getting way too much gas, how about draining the gas or disconnecting the hose and then trying to start it with some spray ether? I had a similar experience here with my mower, spark, wouldn't fire at all with starting fluid sprayed in, etc. Finally it started and ran fine after, I guess it was flooded. You'd think if it was flooded, the spark plug would be wet, but mine wasn't. Cut off the gas, take plug out, crank many times to clear it.

replying to Steve Kraus, Iggy wrote:
99% percent of the time it's just a clogged Fuel Jet from debris in the gas
tank, which is very easy to fix. Be more careful in fueling or add an in-line
fuel filter (
https://www.autozone.com/miscellaneo...ter/366476_0_0
). Definitely, clean that before you do anything else, as I've never had to
replace nor even clean any mower's carburetor and never had the magneto go
bad. This is the best video that shows the simple procedure "EASY FIX! HONDA
PRESSURE WASHER that will not start after storage (plugged carburetor main
jet)" https://www.youtube.com/watch?v=dve9urvVx9o

--
for full context, visit https://www.homeownershub.com/mainte...p-1151432-.htm

If it's a clogged jet then shooting some gas directly in should get it to
at least sputter. In the past it always got a 5 second vrooom out of it.
Let's say, though, that this technique is making it too rich this time for
some reason. But then crank crank crank crank crank would eventually reach
the point where it is just right just for one crank and it would either
vrooom or at least sputter.

But lets say the cheap knockoff carb suddenly decided to go way too rich.
Then it won't do anything and shooting additional gas in will only make
things worse.

On that theory this morning I opened the old carb made sure the holes at
the bottom of the brass plug were clean and reinstalled it.
Again...nothing. Not even the slightest hint of anything. Tried shooting
gas in again and still nothing.

This makes me lean (no pun) towards ignition issues even though I could see
it sparking in my test. But maybe it's really weak. That sparking was in
open air. It could be much more feable in a high pressure situation. I
wish there was a way to test for that.

I can try removing the carb and trying to get it to do something by
spurting in a little gas or maybe put the intake tube on, stuffed with
something wet with gas. Enough screwing around with it and at some point
the mixture will cross into the acceptable range at least for one crank.
But I'm thinking I will still get nothing.



replying to Steve Kraus, Iggy wrote:
99% percent of the time it's just a clogged Fuel Jet from debris in
the gas tank, which is very easy to fix. Be more careful in fueling or
add an in-line fuel filter (
https://www.autozone.com/miscellaneo...l-filter-small
-engine/duralast-5-16-in-universal-top-mount-fuel-filter/366476_0_0
). Definitely, clean that before you do anything else, as I've never
had to replace nor even clean any mower's carburetor and never had the
magneto go bad. This is the best video that shows the simple procedure
"EASY FIX! HONDA PRESSURE WASHER that will not start after storage
(plugged carburetor main jet)"
https://www.youtube.com/watch?v=dve9urvVx9o

replying to Steve Kraus, Iggy wrote:
Yep, you might be in the 1% and it's a bit much to type (don't worry, no tools
are over $10), so here's a very good video for all of those ignition check
and fix procedures "Lawn Mower Won't Start: Spark Plug and Ignition Problems"
https://www.youtube.com/watch?v=3gXUAUyZiWE

If none of that works, then since you've been running it rich for a while or
off and on, you may be dealing with the wrong end and need to torch or scrape
the carbon off the muffler. Very uncommon for 4-cycles to build-up enough to
choke-out the engine, but definitely worth removal from the checklist.

--
for full context, visit https://www.homeownershub.com/mainte...p-1151432-.htm

If none of that works, then since you've been running it rich for a while or
off and on, you may be dealing with the wrong end and need to torch or scrape
the carbon off the muffler. Very uncommon for 4-cycles to build-up enough to
choke-out the engine, but definitely worth removal from the checklist.



the timing could also be off..

did you hit something with the blade?

do you know about the "shear key"

mark

On Tuesday, November 21, 2017 at 3:32:02 PM UTC-5, wrote:

If none of that works, then since you've been running it rich for a while or
off and on, you may be dealing with the wrong end and need to torch or scrape
the carbon off the muffler. Very uncommon for 4-cycles to build-up enough to
choke-out the engine, but definitely worth removal from the checklist.



the timing could also be off..

did you hit something with the blade?

do you know about the "shear key"

mark

Not to hijack his thread, but I had another thread here about my Sears
leaf blower, how the carb would not pump gas. So, I too bought one of
those Chinese carbs. I reported the other day how great it worked,
it started on the first pull. I used it for about an hour that day
it worked great. Today I went to use it again, this time it was hard
to start. I finally got it to fire though, and then it ran fine again,
I used it for about 20 mins. Half an hour later, it won't start!

Like Steve's this one acts like it isn't getting gas. The plug was dry,
I checked it has spark. So, like Steve, I sprayed some starting fluid
right into it, figuring it would at least fire on that. No joy. Tried
several times, with the choke on full, half, off etc. I tried holding
the throttle wide open and pulling it many times, as you'd do if it was
flooded. The only thing I did to it was that when it was last running,
I adjusted the idle speed screw so it idled a little faster. I even
tried unscrewing that a turn, back to about where it was. The way it's
supposed to start is a few pumps of the bulb, pull it with choke on full
until it fires, then half choke and pull till it starts.


Finally gave up for the day. I'll let it set until tomorrow
and try again. Maybe it's time for a new blower. But it's funny that
it's similar problem to Steve's, even though this is a 2 cycle, different
carb, etc.

On Tuesday, November 21, 2017 at 3:22:14 PM UTC-6, trader_4 wrote:
On Tuesday, November 21, 2017 at 3:32:02 PM UTC-5, wrote:

If none of that works, then since you've been running it rich for a while or
off and on, you may be dealing with the wrong end and need to torch or scrape
the carbon off the muffler. Very uncommon for 4-cycles to build-up enough to
choke-out the engine, but definitely worth removal from the checklist..



the timing could also be off..

did you hit something with the blade?

do you know about the "shear key"

mark

Not to hijack his thread, but I had another thread here about my Sears
leaf blower, how the carb would not pump gas. So, I too bought one of
those Chinese carbs. I reported the other day how great it worked,
it started on the first pull. I used it for about an hour that day
it worked great. Today I went to use it again, this time it was hard
to start. I finally got it to fire though, and then it ran fine again,
I used it for about 20 mins. Half an hour later, it won't start!

Like Steve's this one acts like it isn't getting gas. The plug was dry,
I checked it has spark. So, like Steve, I sprayed some starting fluid
right into it, figuring it would at least fire on that. No joy. Tried
several times, with the choke on full, half, off etc. I tried holding
the throttle wide open and pulling it many times, as you'd do if it was
flooded. The only thing I did to it was that when it was last running,
I adjusted the idle speed screw so it idled a little faster. I even
tried unscrewing that a turn, back to about where it was. The way it's
supposed to start is a few pumps of the bulb, pull it with choke on full
until it fires, then half choke and pull till it starts.


Finally gave up for the day. I'll let it set until tomorrow
and try again. Maybe it's time for a new blower. But it's funny that
it's similar problem to Steve's, even though this is a 2 cycle, different
carb, etc.


Are you using gasoline that contains ethanol like E10 or E15? You're not supposed to use ethanol containing gasoline in small engines because they're not designed to use it and it causes damage to small engines. It's best to find a source of alcohol free gasoline for your lawnmower and othe power equipment. ヽ(ヅ)ノ

https://www.consumerreports.org/cro/...fail/index.htm

[8~{} Uncle Gassy Monster

On Mon, 20 Nov 2017 20:57:46 -0600, Steve Kraus
wrote:

I think maybe I will try to give the old carb a good cleaning and
put it back on.

Look inside the carb throat for tiny venturi holes. The only way to
really clean them is with a stainless steel wire plucked from a wire
brush and a pair of needle-nosed pliers. Don't use some wire that may
break off.

The venturi's allow for measured air and fuel mixture in the carb.

If you hit anything substantial a shear pin "could" be bent, but not
broken. Just a slight damage could throw the timing off.

Just sayin'

On Tuesday, November 21, 2017 at 4:38:39 PM UTC-5, Uncle Monster wrote:
On Tuesday, November 21, 2017 at 3:22:14 PM UTC-6, trader_4 wrote:
On Tuesday, November 21, 2017 at 3:32:02 PM UTC-5, wrote:

If none of that works, then since you've been running it rich for a while or
off and on, you may be dealing with the wrong end and need to torch or scrape
the carbon off the muffler. Very uncommon for 4-cycles to build-up enough to
choke-out the engine, but definitely worth removal from the checklist.



the timing could also be off..

did you hit something with the blade?

do you know about the "shear key"

mark

Not to hijack his thread, but I had another thread here about my Sears
leaf blower, how the carb would not pump gas. So, I too bought one of
those Chinese carbs. I reported the other day how great it worked,
it started on the first pull. I used it for about an hour that day
it worked great. Today I went to use it again, this time it was hard
to start. I finally got it to fire though, and then it ran fine again,
I used it for about 20 mins. Half an hour later, it won't start!

Like Steve's this one acts like it isn't getting gas. The plug was dry,
I checked it has spark. So, like Steve, I sprayed some starting fluid
right into it, figuring it would at least fire on that. No joy. Tried
several times, with the choke on full, half, off etc. I tried holding
the throttle wide open and pulling it many times, as you'd do if it was
flooded. The only thing I did to it was that when it was last running,
I adjusted the idle speed screw so it idled a little faster. I even
tried unscrewing that a turn, back to about where it was. The way it's
supposed to start is a few pumps of the bulb, pull it with choke on full
until it fires, then half choke and pull till it starts.


Finally gave up for the day. I'll let it set until tomorrow
and try again. Maybe it's time for a new blower. But it's funny that
it's similar problem to Steve's, even though this is a 2 cycle, different
carb, etc.


Are you using gasoline that contains ethanol like E10 or E15? You're not supposed to use ethanol containing gasoline in small engines because they're not designed to use it and it causes damage to small engines. It's best to find a source of alcohol free gasoline for your lawnmower and othe power equipment. ヽ(ヅ)ノ

https://www.consumerreports.org/cro/...fail/index.htm

[8~{} Uncle Gassy Monster

If it finished off that carb in two days, that would be something.
I know there are issues with ethanol gas, but I've been using it in
mowers and blowers for 25 years without problems, unless you count
the carb on this blower that failed after maybe 8 years and would
not pump gas. Kind of odd it would
all happen now and screw a new carb in two days. But I guess it's a
theory, that the Chinese carbs have something in them that fails
from ethanol in just a couple days. It would explain Steve having
a similar problem. I'm letting it sit overnight, with the plug out,
air it out, try again tomorrow. IF that doesn't work, then I'll take
the carb apart and see what's doing.

On Tue, 21 Nov 2017 13:49:43 -0800 (PST), trader_4 wrote:



If it finished off that carb in two days, that would be something.
I know there are issues with ethanol gas, but I've been using it in
mowers and blowers for 25 years without problems, unless you count
the carb on this blower that failed after maybe 8 years and would
not pump gas. Kind of odd it would
all happen now and screw a new carb in two days. But I guess it's a
theory, that the Chinese carbs have something in them that fails
from ethanol in just a couple days. It would explain Steve having
a similar problem. I'm letting it sit overnight, with the plug out,
air it out, try again tomorrow. IF that doesn't work, then I'll take
the carb apart and see what's doing.

My old string trimmer wouldn't start - not getting gas. My son fixed it and said the gas
tube had basically dissolved in the gas tank. He had it running fine at his house.
But when I went to use it, it wouldn't start. Might have gunked up the carb.
It's +10 years old. Might let him have another try at it, but I'll probably just buy
another one in the spring.

On Tue, 21 Nov 2017 12:31:59 -0800 (PST), wrote:

the timing could also be off..

did you hit something with the blade?

do you know about the "shear key"

mark

.... look for a frayed / cracked plug wire near the cowling.

Spark grounding to the engine block (what ever you call it)?

The shear key only needs a little twist in it to throw timing off. It
may look just fine, but a tiny twist and it needs to be replaced. It
does not have to be broken in half. And. Get the correct size shear
key.

replying to makolber, Iggy wrote:
Yep, that's at 3:38 in the video.


--
for full context, visit https://www.homeownershub.com/mainte...p-1151432-.htm

replying to trader_4, Iggy wrote:
I do question the new carb and hopefully your experience directs him to
reinstalling the old original carb. I can't imagine the metal stuff being a
problem, it's got to be inferior gaskets and diaphragm in your case.

--
for full context, visit https://www.homeownershub.com/mainte...p-1151432-.htm

On Tuesday, November 21, 2017 at 7:14:08 PM UTC-5, Iggy wrote:
replying to trader_4, Iggy wrote:
I do question the new carb and hopefully your experience directs him to
reinstalling the old original carb. I can't imagine the metal stuff being a
problem, it's got to be inferior gaskets and diaphragm in your case.

--
for full context, visit https://www.homeownershub.com/mainte...p-1151432-.htm

The mystery remains, if it's a problem with the new carb failing in just two days, why won't it fire on ether? Like Steve said, you'd think you'd get it to do something with that sprayed in. I'm thinking maybe it got flooded out,though at least at first the plug was bone dry. I'm letting it sit overnight, plug out, try again tomorrow.

I put the old carb back this morning. Still nothing. I opened it and
checked it out before I did. Even if it was gunked up and not giving gas
my shooting some gas in (I tried it the normal way first) should have given
me at least a sputter if not a 5 second vroom.

I do not recall hitting anything that could have broken the shear key. And
the current difficulties started with it not starting but still giving the
5 sec vroom after gas was shot in. It did that a couple of times and then
nothing. Unless the shear key partly broke, was temporarily back in
alignment and then went out of alignment again.

I think I'm gonna remove the carb, put the intake tube back, and stuff it
with cloth and soak it thoroughly with gas. Then crank away. In theory it
should begin too rich and eventually come down to a level that can support
operation at least for a few seconds before it dries out. If I get nothing
not even a sputter then either the timing has gone to hell (shear key or
other reason) or the ignition has failed or is too weak.

Iggy wrote:

replying to trader_4, Iggy wrote:
I do question the new carb and hopefully your experience directs him
to reinstalling the old original carb. I can't imagine the metal stuff
being a problem, it's got to be inferior gaskets and diaphragm in your
case.

replying to Steve Kraus, Iggy wrote:
Sounds good. Follow the 2nd video and don't take anything for granted. Just
because you replaced the spark plug doesn't mean it can't be cracked or
incorrectly gapped. Blow-out or Ream-out the fuel line and replace it if it
has any holes or splits. Make sure the Kill Switch Cable is secure and
operating as it should. It's not always easy, but it's always permanently
repairable. Let us know when you find what the problem was, it's always great
to hear about success and especially bizarre situations.

--
for full context, visit https://www.homeownershub.com/mainte...p-1151432-.htm

Colonel Edmund J. Burke wrote:

Buy a new mower.

I have an older one which is adequate for now.

I don't want to give up on this one without knowing what is going on.

I thought I knew the answer to this but I better check: Does the terminal
on the magneto get grounded to activate ignition or grounded to kill it?

I believe this is a fully solid state unit; no points. What resistance
readings should I see from that terminal to ground, from the plug wire to
ground, and from the plug wire to that terminal?

replying to Steve Kraus, Iggy wrote:
It grounds to kill the mower. Again, I've never had to deal with any of it,
but according to Continuity Testing and the 2nd video (@ 2:10)...if the wire's
good you won't get zeros (it doesn't matter what the numeral(s) is), if the
wire's bad and needs replacement you'll get just 000's.

--
for full context, visit https://www.homeownershub.com/mainte...p-1151432-.htm

On Wednesday, November 22, 2017 at 1:10:37 PM UTC-5, Steve Kraus wrote:
I thought I knew the answer to this but I better check: Does the terminal
on the magneto get grounded to activate ignition or grounded to kill it?

I believe this is a fully solid state unit; no points. What resistance
readings should I see from that terminal to ground, from the plug wire to
ground, and from the plug wire to that terminal?

Did you check for compression? I just did that on my leaf blower that's
giving me trouble. I held my finger over the spark plug hole and pulled
it a few times. I can feel a little suction, no pressure. Sounds like
a stuck piston ring or worse. Should have a gauge to do it right, but
mine is so bad it's obvious. At least that's the theory of the moment.

Iggy wrote:

replying to Steve Kraus, Iggy wrote:
It grounds to kill the mower. Again, I've never had to deal with any
of it, but according to Continuity Testing and the 2nd video (@
2:10)...if the wire's good you won't get zeros (it doesn't matter what
the numeral(s) is), if the wire's bad and needs replacement you'll get
just 000's.


I wasn't really concerned about the wires themselves.

replying to Steve Kraus, Iggy wrote:
You may want to reconsider that.

--
for full context, visit https://www.homeownershub.com/mainte...p-1151432-.htm

I got it to sputter like it was firing on a few turns but no vrooom. I did
go back to the new carb but that seems unrelated as I got it sputtering on
the old as well. This is with many pushes of the primer or shooting some
gas in with a syringe.

I think I will eventually need to drill and tap the intake tube opening on
the block as it seems on the verge of stripping. I know air getting drawn
in will screw things up but for now I am convinced that is not the issue as
I do have it fairly tight and I had already put on a new gasket but now
I've got sealant as well. Also, shooting several CC's of gas would richen
it massively.

So someone said to check the flywheel key:

This is what I see. Is that off? And if it is is it enough to prevent
operation?

http://home.earthlink.net/~filmteknik70mm/flywheel.jpg

I can get a new magento assembly for about $12-13. Is weak spark
sufficiently likely to make that worth a try? My other mower also has a
Tecumseh engine. If they are the same or similar it might be a simple swap
to see if that's the issue.

On 11/26/2017 8:55 PM, Steve Kraus wrote:
I got it to sputter like it was firing on a few turns but no vrooom. I did
go back to the new carb but that seems unrelated as I got it sputtering on
the old as well. This is with many pushes of the primer or shooting some
gas in with a syringe.

I think I will eventually need to drill and tap the intake tube opening on
the block as it seems on the verge of stripping. I know air getting drawn
in will screw things up but for now I am convinced that is not the issue as
I do have it fairly tight and I had already put on a new gasket but now
I've got sealant as well. Also, shooting several CC's of gas would richen
it massively.

So someone said to check the flywheel key:

This is what I see. Is that off? And if it is is it enough to prevent
operation?

http://home.earthlink.net/~filmteknik70mm/flywheel.jpg

I can get a new magento assembly for about $12-13. Is weak spark
sufficiently likely to make that worth a try? My other mower also has a
Tecumseh engine. If they are the same or similar it might be a simple swap
to see if that's the issue.

I've never seen one like that. All mine have the same width slot
in the shaft and the flywheel. Yours seems off, but it looks like
it was designed that way with an offset key.

FWIW, all my Tecumseh starting problems have been carburetor related.
I've soaked them in carb cleaner in an ultrasonic cleaner, then put
in a new kit with no improvement.
Done the same a second time with no improvement.

Put Seafoam in the gas. Waited a week.
Starts a lot easier. Still won't start with
the electric starter, but does if I pull the rope really hard.

I have a 40 year old Briggs lawnmower engine that still starts like new.
I won't buy another engine with a tecumseh carb.

Looks OK to me. Did you check compression?

replying to trader_4, Iggy wrote:
Walk away, he's not checking anything and just keeps trying the same thing,
expecting it to fix itself.

--
for full context, visit https://www.homeownershub.com/mainte...p-1151432-.htm

Looks OK to me.

Yeah, since posting I found a photo of the off-center T shaped key.

Did you check compression?

Sort of. I do not own a gauge; I will have to decide if one is worth
buying for this. I do feel it on my finger if I place it on the spark plug
hole not to mention hearing it wheeze at the exhaust. (Muffler is off for
now.) And it's harder to turn with the

Let's say the compression is bad. Would that prevent it from running at
all (as opposed to running badly or weakly)? What would be the likely
cause? Broken ring? Now that I think about it, when I had the head off
the cylinder did have some scuffs.

On 11/27/2017 10:51 PM, Steve Kraus wrote:
Looks OK to me.

Yeah, since posting I found a photo of the off-center T shaped key.

Did you check compression?

Sort of. I do not own a gauge; I will have to decide if one is worth
buying for this. I do feel it on my finger if I place it on the spark plug
hole not to mention hearing it wheeze at the exhaust. (Muffler is off for
now.) And it's harder to turn with the

Let's say the compression is bad. Would that prevent it from running at
all (as opposed to running badly or weakly)? What would be the likely
cause? Broken ring? Now that I think about it, when I had the head off
the cylinder did have some scuffs.

Neighbor bought a used mower from a friend and the air cleaner hold
down was cross threaded... long story short the cylinder was scuffed and
ruined. I got it to run but just barely. With yours I'd be checking
that and the valve clearance and I once had a lawnboy the old 2 cycle
type.. had spark and would fire and and sometimes run... I finally
notice a spark jump from the back of the coil to ground.. the coil was
cracked and the plug would fire when out of the mower but not under
compression. So you might try a really wide gapped spark plug to test
for something like that. Briggs makes a spark tester if you want to
spend a few bucks. Also make sure the tank is vented properly or drill
a small hole in the cap. Intake manifold gaskets... blah blah blah.
When all else fails try one of these Predator engines from Harbor
Fright.
https://www.harborfreight.com/55-hp-...arb-69731.html
.... wait till they are sale or use the coupons they always have. Happy
mowing !

This morning I tried fingering the spark plug hole on the other mower with
a T engine and not sure I can tell the difference. What was the deal with
"compression release" that they used to advertise as making starting
easier? Maybe it was only on Sears Craftsman mowers with T engines.
Whatever it was, isn't it going to make it harder detect issues?

Unless it really is just a weak spark (jury still out on that), the carb &
gas issues would have been addressed in testing with fuel shot in (the mix
would have been correct at some point) so that just leaves a severe
mechanical issue of some sort and likely not worth fixing.

I'm nearing the point where I'm going to give up. I would then dismantle
the engine just to see what's what. There is actually an extensive Youtube
video series where my exact engine is dismantled and reassembled. That's
probably too much trouble and/or maybe beyond my abilities. But
dismantling as a learning exercise before pitching the metal into recycling
sure, may as well.

On Tuesday, November 28, 2017 at 8:55:05 AM UTC-5, Steve Kraus wrote:
This morning I tried fingering the spark plug hole on the other mower with
a T engine and not sure I can tell the difference. What was the deal with
"compression release" that they used to advertise as making starting
easier? Maybe it was only on Sears Craftsman mowers with T engines.
Whatever it was, isn't it going to make it harder detect issues?

That is what it is and you raise a good point. How do you test for
compression on an engine that has compression release? If you can
get your hand over the carb intake or intake manifold with the carb
off, you could test for suction. Not sure how probative that is
though, ie how you judge how much should really be there by hand.

I guess the compression release thing brings up another point, which
is that to get the engine started, it apparently will start very
readily with a substantial decrease in compression. If it didn't
compression release would not work.





Unless it really is just a weak spark (jury still out on that), the carb &
gas issues would have been addressed in testing with fuel shot in (the mix
would have been correct at some point) so that just leaves a severe
mechanical issue of some sort and likely not worth fixing.

I'm not so sure about the fuel mix being right at some point if you
spray ether or fuel into the carb. It would have a high probability
of being right enough to fire at some point. But on the other hand,
I have seen cases where I sprayed it into a carb on a mower and it
still would not fire. If it's flooded for example, you would flood
it more and might not clear it enough to get it to fire while pulling
X times, etc. But those, I've left alone or left the plug out overnight
and next day it started.





I'm nearing the point where I'm going to give up. I would then dismantle
the engine just to see what's what. There is actually an extensive Youtube
video series where my exact engine is dismantled and reassembled. That's
probably too much trouble and/or maybe beyond my abilities. But
dismantling as a learning exercise before pitching the metal into recycling
sure, may as well.

I had good results with my two cycle leaf blower. It had a gunked up and
stuck piston ring. I took it apart, cleaned it up, with that and the new
$16 Chinese carb, it's running better than ever. This thing went from
running great after I put the new carb on, to not starting at all next
time I tried to use it. Given that, compression was not even on my list,
because I wouldn't think it could go from running full blast to suddenly
not starting due to that. But I guess if the piston ring is getting fouled,
eventually it gets to a point where it sticks and then suddenly it's kaput.

On 11/28/2017 8:21 AM, trader_4 wrote:
On Tuesday, November 28, 2017 at 8:55:05 AM UTC-5, Steve Kraus wrote:
This morning I tried fingering the spark plug hole on the other mower with
a T engine and not sure I can tell the difference. What was the deal with
"compression release" that they used to advertise as making starting
easier? Maybe it was only on Sears Craftsman mowers with T engines.
Whatever it was, isn't it going to make it harder detect issues?

That is what it is and you raise a good point. How do you test for
compression on an engine that has compression release? If you can
get your hand over the carb intake or intake manifold with the carb
off, you could test for suction. Not sure how probative that is
though, ie how you judge how much should really be there by hand.

I guess the compression release thing brings up another point, which
is that to get the engine started, it apparently will start very
readily with a substantial decrease in compression. If it didn't
compression release would not work.





Unless it really is just a weak spark (jury still out on that), the carb &
gas issues would have been addressed in testing with fuel shot in (the mix
would have been correct at some point) so that just leaves a severe
mechanical issue of some sort and likely not worth fixing.

I'm not so sure about the fuel mix being right at some point if you
spray ether or fuel into the carb. It would have a high probability
of being right enough to fire at some point. But on the other hand,
I have seen cases where I sprayed it into a carb on a mower and it
still would not fire. If it's flooded for example, you would flood
it more and might not clear it enough to get it to fire while pulling
X times, etc. But those, I've left alone or left the plug out overnight
and next day it started.





I'm nearing the point where I'm going to give up. I would then dismantle
the engine just to see what's what. There is actually an extensive Youtube
video series where my exact engine is dismantled and reassembled. That's
probably too much trouble and/or maybe beyond my abilities. But
dismantling as a learning exercise before pitching the metal into recycling
sure, may as well.

I had good results with my two cycle leaf blower. It had a gunked up and
stuck piston ring. I took it apart, cleaned it up, with that and the new
$16 Chinese carb, it's running better than ever. This thing went from
running great after I put the new carb on, to not starting at all next
time I tried to use it. Given that, compression was not even on my list,
because I wouldn't think it could go from running full blast to suddenly
not starting due to that. But I guess if the piston ring is getting fouled,
eventually it gets to a point where it sticks and then suddenly it's kaput.

The old style Briggs and Stratton held the intake open just a bit all
the time (they usually had "easy spin" on the recoil starter).. newer
engines most all of them use a centrifugal fling out thing on the
camshaft the keeps the valve open just a wee bit till it's up to speed.
One of the reasons you can't check compression on the small engines.
Is this overhead valve? If so it's really easy to adjust the valves but
go by the book, on some you have to turn the engine a 1/4 way past TDC
so the compression release doesn't give you a false reading. Also it's
rare but a loose blade will give you hell, it acts as the flywheel and
if it's lose the engine will pop but not run.
Spark plugs can be misleading with small engines, they look good but
try one from a known running engine. I use a shot of carb cleaner to
get the little engines to start easy. If you get the word out you'll
get lots of free non running mowers to play with. Folks just go buy a
new one when they quit and put the old one out by the curb. What can
you do with one of the old engines you get running? Here one
thing...https://www.youtube.com/watch?v=ozUwXoIovV0&t=864s

On Sun, 26 Nov 2017 22:55:40 -0600, Steve Kraus
wrote:


So someone said to check the flywheel key:

This is what I see. Is that off? And if it is is it enough to prevent
operation?

http://home.earthlink.net/~filmteknik70mm/flywheel.jpg

I can get a new magento assembly for about $12-13. Is weak spark
sufficiently likely to make that worth a try? My other mower also has a
Tecumseh engine. If they are the same or similar it might be a simple swap
to see if that's the issue.

There all kinds of shear keys.

Regarding the spark, rust on the flywheel magnet and/or magneto
contacts will reduce or prevent strong voltage.

See:

https://www.youtube.com/watch?v=ry-oBVC-Tt4

Interesting development just now.

All along I felt that whatever experiment or test I was trying in an effort
to get this thing going would be that much more likely to succeed with more
vigorous cranking, more than I can manage by hand.

This engine does have a 12V electric starter which runs off a battery one
keeps charged with an external charger. I have not used it in years
because the plastic ring gear on the periphery of the flywheel is chewed up
so I don't even keep a battery installed. So among my experments I tried
hooking it up to my car's battery and hoped that there would be sufficient
momentum to get past the bad parts of the gear but that was not this case.

This morning as I still had the shroud off to look at the flywheel key I
thought I might take advantage of the exposed crankshaft top. I tried
cranking it with an air wrench but it was not fast enough.

So, after rounding up the appropriate adaptors, tried again with an
electric drill. (After the usual shooting some gas into the carb with a
syringe.) I thought it was a lost cause but what the hell, after some
lengthy cranking the engine started to run. Not great...a lot of missing
but it did run. I killed it after a minute as I didn't want it to overheat
without the shroud guiding the air over the cylinder.

I quickly bolted the shroud on and it cranked up with the recoil starter
okay and I put it to the test picking up leaves. I don't know anything
else as I was pretty convinced there was a broken ring or some other
internal calamity. Of course the real test will be starting it cold.

But there you have it. A Festivus miracle!

On Tuesday, November 28, 2017 at 11:02:25 AM UTC-5, Steve Kraus wrote:
Interesting development just now.

All along I felt that whatever experiment or test I was trying in an effort
to get this thing going would be that much more likely to succeed with more
vigorous cranking, more than I can manage by hand.

This engine does have a 12V electric starter which runs off a battery one
keeps charged with an external charger. I have not used it in years
because the plastic ring gear on the periphery of the flywheel is chewed up
so I don't even keep a battery installed. So among my experments I tried
hooking it up to my car's battery and hoped that there would be sufficient
momentum to get past the bad parts of the gear but that was not this case.

This morning as I still had the shroud off to look at the flywheel key I
thought I might take advantage of the exposed crankshaft top. I tried
cranking it with an air wrench but it was not fast enough.

So, after rounding up the appropriate adaptors, tried again with an
electric drill. (After the usual shooting some gas into the carb with a
syringe.) I thought it was a lost cause but what the hell, after some
lengthy cranking the engine started to run. Not great...a lot of missing
but it did run. I killed it after a minute as I didn't want it to overheat
without the shroud guiding the air over the cylinder.

I quickly bolted the shroud on and it cranked up with the recoil starter
okay and I put it to the test picking up leaves. I don't know anything
else as I was pretty convinced there was a broken ring or some other
internal calamity. Of course the real test will be starting it cold.

But there you have it. A Festivus miracle!

Good to see it's working. That's why I told you that I had similar
experiences once in awhile, where you'd think it should fire with ether,
etc, but it would not and just letting it sit for a day with the plug
out, then trying again, it started. I would suspect yours and mine
were simply flooded and it's not as easy to get the right mixture level
in there under all cases as you might think. Hope it keeps going,
I'm off to blow leaves, see if that sucker still starts OK.....

On Tue, 28 Nov 2017 10:02:16 -0600, Steve Kraus
wrote:

Of course the real test will be starting it cold.


Give it Oxygen, Fuel, and Spark. You should be fine.

But there you have it. A Festivus miracle!

Imagine that.

On Mon, 27 Nov 2017 22:51:55 -0600, Steve Kraus
wrote:

Looks OK to me.

Yeah, since posting I found a photo of the off-center T shaped key.

Did you check compression?

Sort of. I do not own a gauge; I will have to decide if one is worth
buying for this. I do feel it on my finger if I place it on the spark plug
hole not to mention hearing it wheeze at the exhaust. (Muffler is off for
now.) And it's harder to turn with the

Let's say the compression is bad. Would that prevent it from running at
all (as opposed to running badly or weakly)? What would be the likely
cause? Broken ring? Now that I think about it, when I had the head off
the cylinder did have some scuffs.
If the compression is low it won't start well. If you are hearing it
"wheeze" at the exhaust port I'd say you most loikely have the exhaust
valve stuck partly open.

On Tue, 28 Nov 2017 10:02:16 -0600, Steve Kraus
wrote:

Interesting development just now.

All along I felt that whatever experiment or test I was trying in an effort
to get this thing going would be that much more likely to succeed with more
vigorous cranking, more than I can manage by hand.

This engine does have a 12V electric starter which runs off a battery one
keeps charged with an external charger. I have not used it in years
because the plastic ring gear on the periphery of the flywheel is chewed up
so I don't even keep a battery installed. So among my experments I tried
hooking it up to my car's battery and hoped that there would be sufficient
momentum to get past the bad parts of the gear but that was not this case.

This morning as I still had the shroud off to look at the flywheel key I
thought I might take advantage of the exposed crankshaft top. I tried
cranking it with an air wrench but it was not fast enough.

So, after rounding up the appropriate adaptors, tried again with an
electric drill. (After the usual shooting some gas into the carb with a
syringe.) I thought it was a lost cause but what the hell, after some
lengthy cranking the engine started to run. Not great...a lot of missing
but it did run. I killed it after a minute as I didn't want it to overheat
without the shroud guiding the air over the cylinder.

I quickly bolted the shroud on and it cranked up with the recoil starter
okay and I put it to the test picking up leaves. I don't know anything
else as I was pretty convinced there was a broken ring or some other
internal calamity. Of course the real test will be starting it cold.

But there you have it. A Festivus miracle!
Put some "top lube" in the gas - something like Marvel Mystery Oil.
Some in the oil too - I'm betting you had a stuck exhaust valve and
you want to free that up.

Clare Snyder wrote:
Put some "top lube" in the gas - something like Marvel Mystery Oil.
Some in the oil too - I'm betting you had a stuck exhaust valve and
you want to free that up.

I cannot rule anything out at this point but I did have the head off at one
point and valves seemed okay. They cannot stick closed, right, only open?

One thing I totally forgot about was there was a time when I yanked the
cord and it just seemed to lock up. I pulled the plug wire and turned it
backwards a bit and then it was okay. Liquid locked? Yes, maybe but who
knows? Up until this morning I was thinking that was further evidence of
some serious internal mechanical issue.

It could be a combination of things. Poor carb, air leaking into the
suction, poor compression, weak spark. Faster cranking might get around
all of them. We shall see.

On Tuesday, November 28, 2017 at 9:47:03 PM UTC-5, Steve Kraus wrote:
Clare Snyder wrote:
Put some "top lube" in the gas - something like Marvel Mystery Oil.
Some in the oil too - I'm betting you had a stuck exhaust valve and
you want to free that up.

I cannot rule anything out at this point but I did have the head off at one
point and valves seemed okay. They cannot stick closed, right, only open?

One thing I totally forgot about was there was a time when I yanked the
cord and it just seemed to lock up. I pulled the plug wire and turned it
backwards a bit and then it was okay. Liquid locked? Yes, maybe but who
knows? Up until this morning I was thinking that was further evidence of
some serious internal mechanical issue.

It could be a combination of things. Poor carb, air leaking into the
suction, poor compression, weak spark. Faster cranking might get around
all of them. We shall see.

One thing not asked in all this is how much service has this mower seen?

Meanwhile my leaf blower is still working better than ever. Blew off
most of the yard, went through two tanks of gas now. I'm behind on leaves
this year because of waiting for the carb and all the repair drama.
But then so too are the leaves because of warm weather. I'd say we're
at least two weeks behind here in NYC area.