small engine: wouldn't run, now won't start.
 

Stihl FS36 string trimmer. Walbro carb, diaphragm pump.

Sad story: starting last year, it would lose power after running for 15 mins or
so. I could usually keep it going by nursing the throttle for a while, after
which it would return to normal power for a few minutes, and then do they same
thing again. This year, it did that same thing the first time I ran it; but,
after that, it would die after running for about 30 seconds. I restarted OK,
but then just died again.

Spark seems OK, but I replaced the plug anyway. No help.

I got a carb rebuild kit, and replaced the filter, needle valve, and the fuel
pump and regulator diaphragms. This was a 'learning experience', and didn't go
that smoothly; but, I got it back to where it would ... do the same thing -
start, run 30 secs, die.

Then, I took out the high-speed adjust screw. (Not gummed up.) Since then, it
won't start. Alas.

The needle valve appears to be working: if I pump the primer bulb with the
regulator diaphragm removed, nothing comes up out of the needle until I press on
the actuator lever; when I do, fuel wells up into the regulator chamber.

AFAICT, the regulator diaphragm is working: if I pump the primer with the carb
assembled, it gets fuel to the regulator chamber. And, if I don't pump the
primer, the regulator stays dry. However, I could be confused about what I'm
seeing, or how to interpret it.

Any suggestions would be appreciated.

Questions:
1. When I press the primer, should I see fuel squirt into the carb throat? (I
don't.)

2. Should I have (liquid) fuel sitting in the crankcase, after trying to start
it repeatedly? (I do.)

Thanks,
George

small engine: wouldn't run, now won't start.
 

"George" wrote in message
...
Stihl FS36 string trimmer. Walbro carb, diaphragm pump.

Sad story: starting last year, it would lose power after running for 15
mins or
so. I could usually keep it going by nursing the throttle for a while,
after
which it would return to normal power for a few minutes, and then do they
same
thing again. This year, it did that same thing the first time I ran it;
but,
after that, it would die after running for about 30 seconds. I restarted
OK,
but then just died again.

Spark seems OK, but I replaced the plug anyway. No help.

I got a carb rebuild kit, and replaced the filter, needle valve, and the
fuel
pump and regulator diaphragms. This was a 'learning experience', and
didn't go
that smoothly; but, I got it back to where it would ... do the same
thing -
start, run 30 secs, die.

Then, I took out the high-speed adjust screw. (Not gummed up.) Since
then, it
won't start. Alas.

The needle valve appears to be working: if I pump the primer bulb with the
regulator diaphragm removed, nothing comes up out of the needle until I
press on
the actuator lever; when I do, fuel wells up into the regulator chamber.

AFAICT, the regulator diaphragm is working: if I pump the primer with the
carb
assembled, it gets fuel to the regulator chamber. And, if I don't pump
the
primer, the regulator stays dry. However, I could be confused about what
I'm
seeing, or how to interpret it.

Any suggestions would be appreciated.

Questions:
1. When I press the primer, should I see fuel squirt into the carb throat?
(I
don't.)

2. Should I have (liquid) fuel sitting in the crankcase, after trying to
start
it repeatedly? (I do.)

Thanks,
George
Not sure about your questions but I had a similar problem with a lawn mower
and garden tractor this year. Lawn mower would only run while pumping the
primer bulb and garden tractor only with full choke until finally not at
all. Had to disassemble the carbs on both and blow all of the passages out
with my air compressor. When put back together they ran just fine. I think
last years gas had jelled and plugged up a vital passageway in the carbs.
Didn't put gasoline stabilizer in last fall as I was in too much of a hurry
to head for Arizona.

Tom G.

small engine: wouldn't run, now won't start.
 

On Fri, 26 May 2006 14:01:42 GMT, lid (Hogwild) wrote:

Unless your carb settings are way off, it sounds like an ignition
problem.

To check for this you can take the plug out, connect and ground it and
pull to see if there is a spark.

I'd donethat - the spark looks good.

small engine: wouldn't run, now won't start.
 

George wrote:
Stihl FS36 string trimmer. Walbro carb, diaphragm pump.

Sad story: starting last year, it would lose power after running for
15 mins or so. I could usually keep it going by nursing the throttle
for a while, after which it would return to normal power for a few
minutes, and then do they same thing again. This year, it did that
same thing the first time I ran it; but, after that, it would die
after running for about 30 seconds. I restarted OK, but then just
died again.

Spark seems OK, but I replaced the plug anyway. No help.

I got a carb rebuild kit, and replaced the filter, needle valve, and
the fuel pump and regulator diaphragms. This was a 'learning
experience', and didn't go that smoothly; but, I got it back to where
it would ... do the same thing - start, run 30 secs, die.

Then, I took out the high-speed adjust screw. (Not gummed up.)
Since then, it won't start. Alas.

The needle valve appears to be working: if I pump the primer bulb
with the regulator diaphragm removed, nothing comes up out of the
needle until I press on the actuator lever; when I do, fuel wells up
into the regulator chamber.

AFAICT, the regulator diaphragm is working: if I pump the primer with
the carb assembled, it gets fuel to the regulator chamber. And, if I
don't pump the primer, the regulator stays dry. However, I could be
confused about what I'm seeing, or how to interpret it.

Any suggestions would be appreciated.

Questions:
1. When I press the primer, should I see fuel squirt into the carb
throat? (I don't.)

2. Should I have (liquid) fuel sitting in the crankcase, after trying
to start it repeatedly? (I do.)

Thanks,
George

Get an electric?

I gave up on all those small gas powered devices long ago and never once
was sorry. Plug and play, no worries about starting or gas.

--
Joseph Meehan

Dia duit

small engine: wouldn't run, now won't start.
 

"Joseph Meehan" wrote in message
.. .
George wrote:
Stihl FS36 string trimmer. Walbro carb, diaphragm pump.

Sad story: starting last year, it would lose power after running for
15 mins or so. I could usually keep it going by nursing the throttle
for a while, after which it would return to normal power for a few
minutes, and then do they same thing again. This year, it did that
same thing the first time I ran it; but, after that, it would die
after running for about 30 seconds. I restarted OK, but then just
died again.

Spark seems OK, but I replaced the plug anyway. No help.

I got a carb rebuild kit, and replaced the filter, needle valve, and
the fuel pump and regulator diaphragms. This was a 'learning
experience', and didn't go that smoothly; but, I got it back to where
it would ... do the same thing - start, run 30 secs, die.

Then, I took out the high-speed adjust screw. (Not gummed up.)
Since then, it won't start. Alas.

The needle valve appears to be working: if I pump the primer bulb
with the regulator diaphragm removed, nothing comes up out of the
needle until I press on the actuator lever; when I do, fuel wells up
into the regulator chamber.

AFAICT, the regulator diaphragm is working: if I pump the primer with
the carb assembled, it gets fuel to the regulator chamber. And, if I
don't pump the primer, the regulator stays dry. However, I could be
confused about what I'm seeing, or how to interpret it.

Any suggestions would be appreciated.

Questions:
1. When I press the primer, should I see fuel squirt into the carb
throat? (I don't.)

2. Should I have (liquid) fuel sitting in the crankcase, after trying
to start it repeatedly? (I do.)

Thanks,
George

Get an electric?

I gave up on all those small gas powered devices long ago and never
once was sorry. Plug and play, no worries about starting or gas.

--
Joseph Meehan

Dia duit

You're sure right on that. I bought a new Stihl top of their line string
trimmer. Just about yanked my arm off trying to start the damned thing. Kept
it a week, gave it away and bought a Black & Decker cordless. As you say,
plug & play. I don't know why anyone would waste time screwing around with a
gas powered trimmer. Anything that is 2 cycle isn't going to be fun to start
regardless of what the packaging says.

Bob

small engine: wouldn't run, now won't start.
 

Try Either-starting fluid to see if the spark is good enough or timing
is right. It has fuel if Either wont do it, its ignition related. I have
the manual if you need factory carb settings.

small engine: wouldn't run, now won't start.
 

It could be a weak spark. Something a new properly gapped plug might
help.

Before adjusting a carb a good practice is to fully seat each screw
and record the number of turns so you can start that way again after
disassembly.

Typically the smaller fuel screw is set at about 1.5 turns, the larger
air screw at about 3.

I suggest, setting the carb, drain the crankcase and try the starting
fluid. (Don't use it too much because it has no lubricating
qualities).

If it only runs with starting fluid, there is something wrong with
your carb.

small engine: wouldn't run, now won't start.
 

"George" wrote in message
...
On Fri, 26 May 2006 14:01:42 GMT, lid (Hogwild) wrote:

Unless your carb settings are way off, it sounds like an ignition
problem.

To check for this you can take the plug out, connect and ground it and
pull to see if there is a spark.

I'd donethat - the spark looks good.


Me too and it still turned out to be a bad ignition coil. Sometimes they
will become intermittant before they finally die.

small engine: wouldn't run, now won't start.
 

Most carbs jet settings are 1 and 1/2 turns out. Becareful not to over
tighten when screwing in to dead bottom. An empty squirt bottle filled
with 2cyl mix squirted directly into the intake is the best try. If
you can keep it running while squirting, then it is the carb or bad
rings. Remember to mark the bottle or empty and destroy, because it
can be very dangerous just sitting around afterwards. Only good way to
test the rings is a compression tester. Less than 50 pounds
compression means big problem.

small engine: wouldn't run, now won't start.
 

According to George :
Stihl FS36 string trimmer. Walbro carb, diaphragm pump.

Sad story: starting last year, it would lose power after running for 15 mins or
so. I could usually keep it going by nursing the throttle for a while, after
which it would return to normal power for a few minutes, and then do they same
thing again. This year, it did that same thing the first time I ran it; but,
after that, it would die after running for about 30 seconds. I restarted OK,
but then just died again.

Your initial problems sounded like the one I had with my FS85.

Turned out to be that the spark arrester on the muffler was plugging
up. It would run somewhat weakly for a while, and then quit.

The small engines guy simply ripped it out, and it worked fine ever
since. [Spark arresters aren't particularly critical where we live.]

Now I'm wondering whether you jarred loose/plugged a fuel line.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

small engine: wouldn't run, now won't start.
 

On Thu, 01 Jun 2006 15:48:53 -0000, (Chris Lewis)
wrote:

According to George :
Stihl FS36 string trimmer. Walbro carb, diaphragm pump.

Sad story: starting last year, it would lose power after running for 15 mins or
so. I could usually keep it going by nursing the throttle for a while, after
which it would return to normal power for a few minutes, and then do they same
thing again. This year, it did that same thing the first time I ran it; but,
after that, it would die after running for about 30 seconds. I restarted OK,
but then just died again.

Your initial problems sounded like the one I had with my FS85.

Turned out to be that the spark arrester on the muffler was plugging
up. It would run somewhat weakly for a while, and then quit.

The small engines guy simply ripped it out, and it worked fine ever
since. [Spark arresters aren't particularly critical where we live.]

Now I'm wondering whether you jarred loose/plugged a fuel line.


Current status: my car won't start.

WRT the trimmer: After a number of disassemble-inspect-reassemble cycles on the
carb, it got to where it sort of ran. I don't think I did anything different,
but I could be wrong about that. Then, I played around with the high speed
mixture, and got to where it better. Now, it starts as well as it ever did (not
on the first pull, to put it mildly), and power is OK. It hasn't died while
running. OTOH, it doesn't start well (like, at all) when it's hot.

So, it's useable, but not really great. Cold compression was 50 psi, which
seems OK. I plan to check the compression when it's hot, but haven't had the
chance.

Thanks,
George

small engine: wouldn't run, now won't start.
 

According to George :
WRT the trimmer: After a number of disassemble-inspect-reassemble cycles on the
carb, it got to where it sort of ran. I don't think I did anything different,
but I could be wrong about that. Then, I played around with the high speed
mixture, and got to where it better. Now, it starts as well as it ever did (not
on the first pull, to put it mildly), and power is OK. It hasn't died while
running. OTOH, it doesn't start well (like, at all) when it's hot.

So, it's useable, but not really great. Cold compression was 50 psi, which
seems OK. I plan to check the compression when it's hot, but haven't had the
chance.

Strange.

My FS85 is over 10 years old now. It's needed no maintenance (other
than the aforesaid spark arrester screen). I do no "prep"
to store it away for the winter (usually leave it half full of gas).

Using the basic instructions in the manual (set switch in start,
full choke, prime 6-7 times, pull until it coughs, then switch to
medium choke, pull), it virtually always starts in the second pull
(first pull under full choke coughs, first pull under medium choke
starts). Even after sitting idle for 6 months.

In contrast to the homelite I used to have - after the first year
it was extremely frustrating to start, and then it started spewing
gas...

Now with a complete overall and new "high performance" carb, that
motor is going to live out the rest of its life powering a windtunnel.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

small engine: wouldn't run, now won't start.
 

Exhaust ports need to be cleaned occasionaly and ethanol in the fuel
can cause problems.