5.5 HP Briggs & Stratton Mower Engine Soaks Air Filter with Gas When Running

I have a 1996 John Deere 14PS push mower with a 5.5 HP Briggs & Stratton Sabre 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?
Mike
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Did you ensure the float tang was adjusted correctly before assembly?
Some primer bulbs have a hole in the center- if it's symmetrical, don't worry about it. If it's a tear, replace it.
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MRC wrote:

[....]
Mike,
the hole in the primer bulb is not a good thing.
Jim
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Some are designed that way.
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platapus03 wrote:

the ones I've seen have no hole. since I've not seen them all and do not know about all different types I'll add your input to the list of new information I've received today.
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Jim Ledford wrote:

Andy comments:
On the Murray I have, the gas is squirted when the primer is pressed, and the air is brought into the bulb when the primer is released. If there is a hole in the bulb, the thumb covers it when the gas is squirted...
I had a hell of a time starting the mower at first because I thought that RELEASING the bulb squirted the gas... I took the air filter off and observed the opposite. Now when I prime, I PUSH very hard and vigorous. Starts on the first pull every time now.....
Just rambling on......
Andy in Eureka, Texas
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