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Fuel pumps but not getting fuel

1991 ford e350 5.8 duel tanks. fuel pump is working but not pumping fuel. second new fuel pump new regulator and filter. why wont it pump fuel?please help going crazy

I am not sure how a fuel pump can be working, but not pumping fuel. Since this is a duel tank deal, is that the possible problem?

got me. the fuel pump is coming on but no fuel coming out. i grounded the fuel pump to try to empty the tank and to elimate the not running problem and found that no fuel was coming from the pump.

Three possibilities I can think of.

  1. the impellar has somehow seperated from the motor shaft. Maybe. Wild guess.

  2. the pump has air around the impellar and needs to be primed. Far more likely. Normally the head pressure would do this, but of you’re emptying the remaining gas from the tank there will be no real head pressure.

  3. the EVAP system is plugged, the tank cannot breath in, you have a vacuum in the tank cavity, and the pump is unable to draw fuel against tha vacuum and is cavitating. That may even explain the original operating problem.

thanks. if it is vacuum how can i fix that? could the selector valve be plugged too? thanks for your help.

If you are working on a fuel pump under the cab, that’s just half the pumping. There is a low pressure pump in the tank which carries fuel to the high pressure pump on the frame of Fords of that era.

is there a low pressure pump in the front tank as well as the rear tank?