I have a 1996 John Deere 14PS push mower with a 5.5 HP Briggs &
engine. Last weekend after I finshed mowing the lawn, I noticed gas
drips on the deck under the air cleaner housing. When I opened the
housing, the bottom part of the filter element was soaked with gas.
This model has a float carb with no adjusting screws or choke and no
throttle control, but it does have a primer bulb. I cleaned the deck up
and no more gas leaked out while it wasn't running.
I took the carb apart, and it didn't have any dirt or sludge in the
bowl, so I gave it a quick clean with mineral spirits (didn't have carb
cleaner) and replaced the float valve and seat then reassembled it with
new gaskets. I put in a new filter element and mowed half of my yard
before I noticed that the gas was dripping from the air cleaner again.
Just an observation, but the little nib in the center of the primer
bulb has a hole in it. I'm not sure whether this is normal or even if
not whether it is relevant to the problem. I've had it suggested to me
that perhaps the intake valve isn't seating properly, such that the
airflow in the carb throat might momentarily reverse during the
compression stroke. Any ideas?