25hp intake nipple backfiring fuel

[Ranger162]

Hello. For some reason there is fuel backfiring out of the small nipple located below the carburetor on the intake. This is connected to the primer system.
Cannot achieve full throttle unless I pull the hose off the nipple and allow it to remain open. Can someone please help me resolve this issue

 

[tphoyt]

What type of primer do you have?
Manual or electric?
If electric is the red lever in the manual position?
If manual the seals could be shot.

 

[Ranger162]

What type of primer do you have?
Manual or electric?
If electric is the red lever in the manual position?
If manual the seals could be shot.

It is manual. I now have the line from the bowl to the primer pinched off and it’s still happening.

 

[flyingscott]

do you have a lean sneeze? Is that the oil recirc line to the top bearing?

 

[racerone]

Perhaps the carburetor is flooding or motor is running on 1 cylinder.----Inspect fuel pump diaphragm too.