Have just completly rebuilt a 12F802-1975-B1 briggs engine. All new gaskets, new air filters, completely cleaned carby (including venturi holes in the nut on the bowl), reseated valves, clean oil, new fuel - basically brand new inside and out.
Once primed, the engine will start, but then stop after 1-3 seconds. Continued priming will keep the engine going, but it stop immeditely once priming has stopped.
I can also get the engine to run if I manually choke it , but limiting air intake.
All this leads me to believe one of two things is happening.
1. Its getting too much air
2. Its getting not enough fuel
I have checked all gaskets and seals between the air filter and intake, and everything looks fine with no obvious air leaks.
The carby float seems to be working as intended, and the bowl is full of fuel, and all passages have been very well cleaned with carby cleaner, wire, and compressed air. So I am running out of ideas as to where the extra air might be coming from, or where the fuel is not coming from?
Any assistance would be greatly appreciated.