I have a 77 E350 motorhome with a 460 engine. I am having what appears to be fuel problems. I replaced the carburetor, fuel filter and tank switching solenoid and have not solved the problem. The engine sometimes will spit and sputter when applying the gas pedal and if you let off, it gets a little better, then if you just ease on the throttle you can slowly build up speed. I have checked the mechanical fuel pump and there are no signs of leakage from the weep hole. Also when sitting at a stop light, when you press the accelerator, it doesnt even have enough power to move forward, I have to put it in neutral or park and partially press the accelerator and then put it in drive. It has 2 fuel tanks. When this problem starts, I have pulled the fuel filter off and there is fuel up to the filter and the filter is clean. Please help as I have done everything I know to correct this problem to no avail. Thanks so much
It is possible at this point, that it is not a fuel problem. Was it the same before you did any work? Checking the mechanical fuel pump for external leakage is just part of the diagnosis, it doesn't tell you if you have adequate fuel pressure, which I would think is only 3-5 psi. If it is filling the float bowl, you should not have any initial acceleration problems. Has the ignition timing and spark output been checked? If you have low spark output, you could have these symptoms. Also if you have a base timing concern, or little or no advance occurring, you could also have the symptoms. If when you check the timing, and the mark is floating around, it could indicate a worn distributor gear, worn distributor, or worn timing chain and gears. Another possibility, if it has one, is the catalytic converter becoming restricted. If it is not letting full exhaust through the engine, you will not have full intake into the engine.