Posted by JohnD [71.125.160.36] on Monday, July 01, 2013 at 18:59:31 :
In Reply to: Mechanical fuel pumps rock! posted by Dan(NH) [173.9.49.14] on Monday, July 01, 2013 at 15:57:15 :
I suspect a suction leak between the pump and the tank. You won't see gas leaking from this leak because it's sucking air in instead of leaking gas out.
Another possibility is dirt in the check valves inside the pump. If one of the valves is stuck open with a little piece of dirt, the gas merely moves back and forth in the line without advancing to the carb. It's less likely the cause.
Look for a suction air leak between the pump and the fuel tank (suction side of the pump)