Expert: Everett Peacock - 4/21/2009

Question
My 5.7 LXEFI runs great for the first hour then it bogs down then goes up again. This will continue until the engine stops. This happens at load only and only when it is running in the water. This will not happen when the engine is in a tank on the trailer. The engine will eventually die unless I take it to 1000 rpm. Fuel pump and pressure regulator were replaced and throttle body fuel injectors working fine. All electrical systems good and vacuum lines ok.
Could it be in the fuel tank or the pick up tube?  

Answer
it could be the valve at the tank...where the fuel line connects to the tank, there is a valve that keeps the fuel from syphoning out if a break in the fuel line occures...remove the valve and inspect, it should be free,  it has a ball and spring in it..it should open with a small amount of suckshion....