All,

Patient is a 2 month old Craftsman with a 4.5 HP Briggs and Straton
motor. Gas is fresh, oil is up to full mark. Mower has been working
OK. Last used about 1.5 weeks ago.

The mower will fire briefly if the primer dome is pushed. Then it
dies after using the gas supplied by the primer push.

I have tried taking the air filter off and have tried loosening the
gas cap (one thing at a time) with no change in results.

Seems as though it is not pulling gas after the initial firing. This
is a new mower with only one run speed. The carb seems bone simple.

Any ideas where to start?

Douglas

"Douglas Fifield" wrote in message
...
All,

Patient is a 2 month old Craftsman with a 4.5 HP Briggs and Straton
motor. Gas is fresh, oil is up to full mark. Mower has been working
OK. Last used about 1.5 weeks ago.

The mower will fire briefly if the primer dome is pushed. Then it
dies after using the gas supplied by the primer push.

I have tried taking the air filter off and have tried loosening the
gas cap (one thing at a time) with no change in results.

Seems as though it is not pulling gas after the initial firing. This
is a new mower with only one run speed. The carb seems bone simple.

Any ideas where to start?

Check and make sure you have not gotten a small pin hole in the primer bulb.
If this happens, it will do exactly what you are describing.

Douglas

On Sun, 24 Jul 2005 20:29:13 GMT, "Old_boat"
wrote:


"Douglas Fifield" wrote in message
.. .
All,

Patient is a 2 month old Craftsman with a 4.5 HP Briggs and Straton
motor. Gas is fresh, oil is up to full mark. Mower has been working
OK. Last used about 1.5 weeks ago.

The mower will fire briefly if the primer dome is pushed. Then it
dies after using the gas supplied by the primer push.

I have tried taking the air filter off and have tried loosening the
gas cap (one thing at a time) with no change in results.

Seems as though it is not pulling gas after the initial firing. This
is a new mower with only one run speed. The carb seems bone simple.

Any ideas where to start?

Check and make sure you have not gotten a small pin hole in the primer bulb.
If this happens, it will do exactly what you are describing.

Douglas


Do you have a suggestion on how to check for a pin hole? Thanks.

D.

"Douglas Fifield" wrote in message

Patient is a 2 month old Craftsman with a 4.5 HP Briggs and Straton
motor.

Seems as though it is not pulling gas after the initial firing. This
is a new mower with only one run speed. The carb seems bone simple.

Any ideas where to start?

Sure, start at Sears. At two months it is under warranty ad you don't want
to tinker with it and void the warranty. Let them figure it out.

"Douglas Fifield" wrote in message
news
On Sun, 24 Jul 2005 20:29:13 GMT, "Old_boat"
wrote:


"Douglas Fifield" wrote in message
. ..
All,

Patient is a 2 month old Craftsman with a 4.5 HP Briggs and Straton
motor. Gas is fresh, oil is up to full mark. Mower has been working
OK. Last used about 1.5 weeks ago.

The mower will fire briefly if the primer dome is pushed. Then it
dies after using the gas supplied by the primer push.

I have tried taking the air filter off and have tried loosening the
gas cap (one thing at a time) with no change in results.

Seems as though it is not pulling gas after the initial firing. This
is a new mower with only one run speed. The carb seems bone simple.

Any ideas where to start?

Check and make sure you have not gotten a small pin hole in the primer
bulb.
If this happens, it will do exactly what you are describing.

Douglas


Do you have a suggestion on how to check for a pin hole? Thanks.

No not really I found it on my sears mower by accident, Thing drove me nuts.
Seemed that the primer bulb has a tiny hole in it around the edge where it
was connected to the housing. I smeared some some blue permatex and it
fised the problem.

LJ

D.

could be you have water in the bowl or dirt in the bowl nut orfice

On Sun, 24 Jul 2005 20:51:41 GMT, "Edwin Pawlowski"
wrote:


"Douglas Fifield" wrote in message

Patient is a 2 month old Craftsman with a 4.5 HP Briggs and Straton
motor.

Seems as though it is not pulling gas after the initial firing. This
is a new mower with only one run speed. The carb seems bone simple.

Any ideas where to start?

Sure, start at Sears. At two months it is under warranty ad you don't want
to tinker with it and void the warranty. Let them figure it out.


I called Sears and the "kid" I talked to said that if I brought it in,
they would send it out for repairs. Probably take 1.5 to 2 weeks.
Before I did that, I wanted to check with the wisdom of the list and
see if there was something simple I could check and perhaps avoid the
hassle.

D.

On Sun, 24 Jul 2005 20:00:47 -0500, Douglas Fifield wrote:

Sure, start at Sears. At two months it is under warranty ad you don't want
to tinker with it and void the warranty. Let them figure it out.

I called Sears and the "kid" I talked to said that if I brought it in,
they would send it out for repairs. Probably take 1.5 to 2 weeks.
Before I did that, I wanted to check with the wisdom of the list and
see if there was something simple I could check and perhaps avoid the
hassle.

Take it in there, and tell them you want a "loaner" to mow your grass with
while yours is out for repairs.

By the way, this isn't a "list", it's a newsgroup.

--
If you're not on the edge, you're taking up too much space.
Linux Registered User #327951

Float is stuck??? Maybe....

I'd remove the bowl and gumout everything.

Check to make sure that dirty gas isnt clogging up the
fuel tank would be good too. Gravity needs to have it
flow nice and easy.

On 25 Jul 2005 08:24:24 -0700, wrote:

Float is stuck??? Maybe....

I'd remove the bowl and gumout everything.

Check to make sure that dirty gas isnt clogging up the
fuel tank would be good too. Gravity needs to have it
flow nice and easy.

The fuel tank is underneath the carburator. Gravity is not a friend
in this case.

D.

Fuel tank is underneath??? What the???

Crappy design then. If thats the case then
there has to be some sort of pump to get
the gas into the bowl. Sometimes they
use a small diaphram pump that works off
of crankcase pressure. These do go bad too.


What are you worried about right now if its
under warranty then have it taken care of by
them ASAP. Then just get back to us
and say what the problem is/was

Tom

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 25 Jul 2005 17:20:11 -0700, wrote:

Fuel tank is underneath??? What the???

Yep.

Crappy design then.

Not at all.

If thats the case then
there has to be some sort of pump to get
the gas into the bowl.

Atmospheric pressure.


Sometimes they
use a small diaphram pump that works off
of crankcase pressure. These do go bad too.

Chain saws are likely to have "diaphragm carburetors", while lawn
mowers may have "suction carburetors". The fuel tank bolts directly
to the bottom of the carburetor. There is no float or float bowl.
Fuel is sucked directly into the venturi through the pickup tube and
main metering jet.

What I have seen happen, especially on new mowers, is the pickup
tube, which is threaded into the carburetor body, isn't tight, and
vibrates off, falling into the tank. This will stop the mower cold,
except for running off the primer. You can feel for the tube by
sticking your finger through the filler opening. It might be laying
in the bottom of the tank, if it came loose.

Also check for water in the fuel. It's hard to see, because the
tank probably has no drain. Siphon out the fuel and dry the tank out
with compressed air.

The pickup tube sometimes has a check ball that can get gummed up and
stuck, but a carburetor isn't likely to gum up in two months.

Some kid didn't turn the mixture screw all the way in, just to be
cute, did he? I've seen that before, too.


-----BEGIN PGP SIGNATURE-----
Version: PGP 7.1

iQA/AwUBQuWijQIk7T39FC4ZEQIkHQCfQDwAXuWuzAu0ftFtRggedR tWSV0AoOEw
R2kpToUMXkqRa9gTpzc8uRF3
=fO5h
-----END PGP SIGNATURE-----

--
-john
wide-open at throttle dot info

On Mon, 25 Jul 2005 20:37:12 -0700, ~^Johnny^~
wrote:

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 25 Jul 2005 17:20:11 -0700, wrote:

Fuel tank is underneath??? What the???

Yep.

Crappy design then.

Not at all.

If thats the case then
there has to be some sort of pump to get
the gas into the bowl.

Atmospheric pressure.


Sometimes they
use a small diaphram pump that works off
of crankcase pressure. These do go bad too.

Chain saws are likely to have "diaphragm carburetors", while lawn
mowers may have "suction carburetors". The fuel tank bolts directly
to the bottom of the carburetor. There is no float or float bowl.
Fuel is sucked directly into the venturi through the pickup tube and
main metering jet.

What I have seen happen, especially on new mowers, is the pickup
tube, which is threaded into the carburetor body, isn't tight, and
vibrates off, falling into the tank. This will stop the mower cold,
except for running off the primer. You can feel for the tube by
sticking your finger through the filler opening. It might be laying
in the bottom of the tank, if it came loose.

Also check for water in the fuel. It's hard to see, because the
tank probably has no drain. Siphon out the fuel and dry the tank out
with compressed air.

The pickup tube sometimes has a check ball that can get gummed up and
stuck, but a carburetor isn't likely to gum up in two months.

Some kid didn't turn the mixture screw all the way in, just to be
cute, did he? I've seen that before, too.


-----BEGIN PGP SIGNATURE-----
Version: PGP 7.1

iQA/AwUBQuWijQIk7T39FC4ZEQIkHQCfQDwAXuWuzAu0ftFtRggedR tWSV0AoOEw
R2kpToUMXkqRa9gTpzc8uRF3
=fO5h
-----END PGP SIGNATURE-----


UPDATE:

Tried the mower today and it started and ran fine. Only difference
between today and two days ago is:

1) passage of time, and

2) temperature and humidity.

Two days ago it was beastly hot and humid. Today, the temps are in
the low 70's (F) and the humidity is much lower. Everything else is
the same.

Douglas

Yeah, this happened to me.
In my case, the ventri was clogged from the varnishes in the gas.
Of course when you choke it and start up, you are basically
manually making the rich mix in the carb. So it starts fine
and dies in 2 seconds.
If you don't use gasoline stabilizer, DO. It prevents gum-up
in the venturi. I swear by this now after several weeks of
intermitent behavior and crazy starts.
I would add this to your gas can, and to the remaining gas in
your tank. Consider cleaning your carb if this is recurring.
The other thing about humidity could be a leaky electrical
connection.. Is the plug new?

How does it keep the constant flow coming into the carb with
the pulse vacuum of the engine in one of these types of carbs????

On Tue, 26 Jul 2005 21:26:50 -0500, les wrote:

Yeah, this happened to me.
In my case, the ventri was clogged from the varnishes in the gas.
Of course when you choke it and start up, you are basically
manually making the rich mix in the carb. So it starts fine
and dies in 2 seconds.
If you don't use gasoline stabilizer, DO. It prevents gum-up
in the venturi. I swear by this now after several weeks of
intermitent behavior and crazy starts.

He said the mower was 2 months old, and the gas was fresh. Do you really
think the "ventri" is clogged? Do you think you need stabilizer over the
summer when it's used every week?

I would add this to your gas can, and to the remaining gas in
your tank. Consider cleaning your carb if this is recurring.
The other thing about humidity could be a leaky electrical
connection.. Is the plug new?

You're quite the mechanic, huh?

--
If you're not on the edge, you're taking up too much space.
Linux Registered User #327951

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 26 Jul 2005 19:55:48 -0700, wrote:

How does it keep the constant flow coming into the carb with
the pulse vacuum of the engine in one of these types of carbs????

It doesn't need to.

In fuel injected auto engines, for instance, fuel can be sprayed
into the intake manifold in extremely short pulses, at idle. It all
mixes during induction and comopression.


-----BEGIN PGP SIGNATURE-----
Version: PGP 7.1

iQA/AwUBQucIgwIk7T39FC4ZEQJ7SACbBrGlAj+s3s9lNAv/EGMKDtpIpBMAnjoo
24HverQrdKJmY5weJbQZdcHW
=gcp2
-----END PGP SIGNATURE-----

--
-john
wide-open at throttle dot info

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Wed, 27 Jul 2005 11:02:00 -0700, "les" wrote:

Dan...
Sure, I stick to my guns. I had new gas and the venturi was plugged
from week to week.Small embuli of crude was contaminating the
orifice akin to a cardiac vessel, and resurfaced once the pressure
pulled it back into position.
I'm offering possible scenarios. I'm not a mechanic, though a doctor
sees things from his perspective and is willing to share
experiences. Hope you feel better.......

Les



I understand. After all, I'm no doctor; but, if I can overhaul a
carburetor, surely I should be able to perform open heart surgery,
shouldn't I?

Or should I operate in vein? I can see a car, rotted. ;-




-----BEGIN PGP SIGNATURE-----
Version: PGP 7.1

iQA/AwUBQufIIgIk7T39FC4ZEQIhbgCg5vyjZL2uIURHyELzBC7OFm 0cAr4AoMfy
jgEcil4heBS05tItdInwQvh1
=qP6k
-----END PGP SIGNATURE-----

--
-john
wide-open at throttle dot info

Dan...
Sure, I stick to my guns. I had new gas and the venturi was plugged
from week to week.Small embuli of crude was contaminating the
orifice akin to a cardiac vessel, and resurfaced once the pressure
pulled it back into position.
I'm offering possible scenarios. I'm not a mechanic, though a doctor
sees things from his perspective and is willing to share experiences.
Hope you feel better.......

Les