Posted by Johnd [162.158.79.248] on Friday, May 31, 2019 at 07:12:05 :
In Reply to: Re: Fuel issue update, looking for flaws in my logic posted by Milo in Pa [162.158.78.253] on Thursday, May 30, 2019 at 16:56:45 :
Mark,
Your fuel system has two parts, a suction side between the tank and the fuel pump, and a pressure side between the pump and the carb. Right now, you dont know which one is bad, so use this process:
Disconnect the line from the pump to the carb. Crank the engine to see if fuel is squirting out of the line you disconnected. If not, your suction side of the pump is bad. To test the pump itself, disconnect the suction line from the pump, replace it with a temporary hose and stick it in a small can of gas. Crank the engine again to see if the pump starts to squirt fuel. If it does, your pump is good, and you can focus on the tank suction line. If not, take the pump apart and try to clean it, or rebuild it.
If the fuel pump suction test proves OK, put your finger over the discharge from the pump while cranking to see if it has decent pressure. It might squirt fuel without any restriction on the discharge side, but fail to pump under pressure.
The tests above will allow you to use a process of elimination to find the exact cause of your fuel starvation so you can fix it.
Note a leak in the suction line from the tank to the fuel pump wont typically be visible because it is a vaccum leak (sucking air in) instead of a fuel leak where fuel squirts out under pressure. A TINY leak in the suction line will cause the very problem you are having.