My lawnmower (20 year old B&S 3.5 HP) won't run if it gets tilted to the
right as seen from the pushing-the-mower position. It acts like it's not
getting gas. If I tilt it back to the left it starts going again just fine.
When tilted to the right the low point of the gas tank would be even lower
so I'm sure it's getting gas to the fuel line when it stops. I checked the
carb floats and they seem to be functioning properly. The fuel line is new.
The fuel flows freely through the line. The air cleaner looks good. I
sprayed the carb with carb cleaner. I removed the jet and cleaned it too.
I even made sure the gas tank was full. Oil level is just a tad high.
Any ideas? I have to mow hilly areas and it's not always easy to get my
approach with the mower tilted just the right way ;-)
You've checked all the things that I would have, so...
A few questions to maybe help you narrow it down:
1. How long after it gets tilted to the right does the engine start
2. If you "catch it" before the engine stops completely and level the
mower, how long before the engine sounds right again?
3. Can you eyeball the throttle arm on the carb and see if maybe it's
moving towards its closed position when the mower is tilted? (It should
move toward the *open* postion when the engine slows.)
4. I know you said it's a 20 year old mower, so it's probably like most
of my old power equipment, a "widow maker" without a bunch of safety
features to keep the legal sharks away. But maybe (long shot) there's
some kind of electrical engine killing safety which is acting up when
the mower is tilted?
5. How long since you looked at/cleaned the air filter? (Another long
shot.) But, try tilting it with the air cleaner off, you might see/learn
something that way.
Check for a frayed wire that may be shorting out. Particularly the
magneto wire. Also be sure the spark plug wire is not cracked. You
could also have a loose or broken shut off contact switch.
My first thought was the carb float, but you said you checked that.
Also be sure there is not water in the gas, since the water will stay
on the lowest point. A little "Heet" should fix any residual water
after you drain the tank.
One last thing. Is there a loose bolt or other metal object in by the
points that is shorting them? (points are under the flywheel).
It starts to sound like it's dieing after just a few seconds.
It also starts to come back to life after just a few seconds.
In the past the problem seemed to be caused by debris collecting on the
throttle arm and worked fine after I cleaned it off. Right now it's
difficult to see it because the air cleaner covers it and I just don't have
a large expanse of concrete etc where I could try running it without the air
cleaner for test purposes.
I'll check that. I have removed/disabled many of the "safety" features as
they pretty much prevent me from being able to start the engine and it's a
real pain-in-the-butt to have to shut the thing off so I can move something
out of the way etc so the ground lever on the handle is taped into the run
(open) position. As a matter-of-fact I have quite a collection of parts
that used to be on the lawnmower and it just keeps getting better the more
junk I remove ;-) Come to think of it I'll bet you are right and it's the
grounding lever that is hitting something when tilted one way.
The air cleaner is clean and I've tried it with it removed (short period)
and it was the same.
Well, I removed the grounding lever and disconnected it from the ignition
coil. I removed the float bowl and the float and checked for holes etc and
found nothing. I checked the float bowl gasket. I removed the gas tank and
emptied it and cleaned it out thoroughly. I replaced two missing screws
that hold on the sheet metal. I cleaned debris from around the linkage. It
still dies when tilted to the right.
My next (and maybe final) try will be to replace the carburator with one
from a Coleman generator (which is identical except for the linkage.
Actually is the same engine except for the crankshaft and the oil fill and a
couple of other minor details. If this doesn't work then I guess it's time
to get a Honda engine.
I had the same issue with a 20 YO Tecumseh powered rider.
Thought it was needle and seat issue. Replaced to no avail.
Found it to be a pinhole in the float.
Replaced and it runs like new.
Typically the only things that are effected by level would
be fuel delivery system and possibly a wire thats hanging
and only grounds out with a certain tilt. Engine stall should be
instantaneous, not a few seconds after tilting.
I still go with a bad float.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.