There are 2 different primers.
One has no hole and pumps fuel into the carb throat
This became EPA non- compliant so it got replaced with the problematic air primer.
The early one has no hole in it so it is just a rubber dome.
The latter type has a hole in the middle of it.
It works by pressurizing the float chamber which forces the float to open and raise the fuel level in the float bowl.
This type, apart from continually fouling up so you end up venting 10,000 times more fuel to the atmosphere than the old works every time "dirty" type, trying to fix it.
As such you do not see fuel squirting into the carb throat when priming the air prime type.
So tarting from first principles, which primer do you have.
Fuel or air ?
I have replaced the air cleaner base and used up to 3 gaskets. No Luck!
New fuel lines and in line fuel filter with large end towards gas tank.
There is free flow of fuel to the carburetor also new. There is gasoline in the fuel bowl.
Have repeatedly cleaned bowl but orifices, main jet, and opening where the air base air steam connects with the fuel bowl. It is open. I have a new primer bulb with a hole. When pressed air is escaping from the proper orifice in the air base.
I found and replaced a missing gasket in the intake of the combustion chamber.
One bolt of the EGR Cover was missing. Reed valve was confirmed to be open working
The EGR tube was patent. The missing bolt was replaced.
Tomorrow I will retry priming the mower.
I don’t not have any metal or plastic opening in air base to be able to observe whether primer is ejecting fuel from the main fuel port.
After attempts at prior priming the spark plug is DRY.
I am able to get the mower to start and stay running when using starter fluid in the spark plug hole!
When cleaning carburetor the float height appears to be correct. I cannot adjust float height because the float is non adjustable plastic and not metal. Again this carburetor is new and was set at factory.
I cannot for the life of me figure out why this primer won’t work.
I can’t find any other leaks anywhere!!!
Any more suggestions on diagnosis and fix greatly appreciated!
Having to use starter fluid in the spark plug hole or into the card thru the air cleaner just isn’t acceptable!
I am starting to believe that this is poor engine design flaw by Briggs.
The mower engine is in great shape re the valves pistons and combustion chamber. I have a feeling the Primerfailure caused the prior owner not to use the mower!