I'm 90% certain the fuel pump is bad but I don't want to replace it unless I'm sure.

The problem: I'm having a crank no start situation. I have spark on all the plugs so I know my coil & crank sensors are good.
The fuel system primes when you turn it on but it will not hold pressure. It tops off at around 30 psi then drops. If I jump the pump relay (with my multimeter) I can get the pump to hold 42 psi. If I remember right I think the 5.2 needs 42-52 psi to be happy.. don't quote that though.. The multimeter reads 4.3 amps so with that I can figure that the pump has at least an ok ground. I was wondering if anyone knew how many amps the fuel pump should be pulling? Also, I'm wondering if their is a way to test for a leaking injector? If I can rule out the injectors then I know that the pressure loss is happening inside the pump/regulator. No external fuel leaks.

Thanks!

 

Did you ever solve this issue? I have a pressure loss, changed fuel pump and it still didn't help. Thinking either cleaning or replacing injectors is next.

 

Don't know how much this helps months down the road, but fuel pressure should be around 50psi.

 

pump draw is usually around 6 amps...diagnostically all it tells you is the wiring is good...unless you can put a labscope on it and view the waveform.


if you have leakdown you must test to isolate the leak source. possilble sources are the pressure regulator, injectors or fuel pump check valve...if it is a returnless system, the regulator is in the pump. I would pressurize the system and find a place to clamp off the feed line. if the pressure holds, the injectors are ok.

 

Regulator, check valve, and filter are all in the pump. I got done replacing my pump this weekend because of it leaking down pressure when the pump wasn't running. Injectors usually leak down slowly, whereas in my case the rapid leakdown was something in the pump.