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Old 03-09-2006, 09:46 PM posted to rec.gardens
Ether Jones Ether Jones is offline
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First recorded activity by GardenBanter: Aug 2006
Posts: 7
Default riding mower leaking gasoline


Gideon wrote:
Ether Jones wrote
The only way I can figure that gasoline could get from the tank to the
exhaust is through the float valve in the carb. Do most inexpensive
carbureted riding mowers nowadays have a float valve in the carb and no
shutoff valve in the gas line??

------------

Yes.

You didn't ask, but a common cause for your problem is a
small bit of debris holding the float valve open. The cure is
a simple cleaning. The prevention is to be extremely careful
to get gasoline and only gasoline into the fuel tank when
refueling. It doesn't take much of a bit of grass clipping,
dust, dirt, etc. to cause a problem.


There's a filter in the gas line from the gas tank to the carb.
Although I am extremely careful about cleanliness when filling the gas
tank, I doubt if any debris in the tank large enough to cause a problem
in the carb could ever get past that filter.

I changed the gas line and gas filter two years ago. I spent an hour
cleaning the gas line fittings with a toothpick and toothbrush and
Q-tips and vacuum before removing the gas line, to make sure no debris
got into the fittings. I inspected the new gas line before installing
and noticed it had manufacturing debris inside it! I washed it out
with fresh gasoline before installing. I'm pretty sure there is no
debris in the carb.

I had a friend who took his riding mower to the place of purchase for a
"tune up". Among other things, they replaced the gas line and gas
filter. His mower hasn't run right since. I told him some high school
kid probably replaced the gas line and got debris in there that found
its way to the carb.

Back to the gas leak: In my case, I had run the mower out of gas and
it sat that way for a week before I filled the tank with fresh gas. A
couple of hours later I noticed the leak. I NEVER run the carb dry
on this engine; this was a one-time aberration. I'm convinced there
is a direct correlation between running the carb dry, and the leak. I
have the service manual for the engine but it gives no details about
the float valve design. I stopped the leak by tapping lightly on both
sides of the carb with a piece of iron rebar.

Has anyone else ever experienced this sort of problem? What's the
street wisdom on fuel additives for cleaning the float valve?

The engine is a 4-cycle Briggs 16.5HP L-Head opposed twin. Does anyone
know if the float valve seal is brass, or some sort of elastomer?