Help with fuel pressure question. 2003 V6

[CarlosV]

I am trying to figure out why recently I get occasional longer cranking times.

The fuel pressure goes to “0” inmediatly after turning off the engine. (Running is at 40-41psi.) Is this definitely abnormal? No obvious leak…

Thanks

 

[4r-4ever]

looks like your fuel pump is on it's way out. fuel pressure should slowly decrease.

I am trying to figure out why recently I get occasional longer cranking times.

The fuel pressure goes to “0” inmediatly after turning off the engine. (Running is at 40-41psi.) Is this definitely abnormal? No obvious leak…

Thanks

 

[BlackWorksInc]

You likely have a bad fuel pressure regulator allowing pressure to just blow out the return line (or a faulty pump doing the same).

The pressure regulator should be easy to test, just block off the return line and do a fuel pressure test, if it's still dropping to zero then it's probably back feeding through the fuel pump.

 

[CarlosV]

looks like your fuel pump is on it's way out. fuel pressure should slowly decrease.

Thanks 4r. What in the pump will not hold pressure, when the car&pump is off?

 

[CarlosV]

You likely have a bad fuel pressure regulator allowing pressure to just blow out the return line (or a faulty pump doing the same).

The pressure regulator should be easy to test, just block off the return line and do a fuel pressure test, if it's still dropping to zero then it's probably back feeding through the fuel pump.

Thanks BWInc. Will check pressure regulator.
Back feeding thru the pump back into the tank?

 

[CarlosV]

You likely have a bad fuel pressure regulator allowing pressure to just blow out the return line (or a faulty pump doing the same).

The pressure regulator should be easy to test, just block off the return line and do a fuel pressure test, if it's still dropping to zero then it's probably back feeding through the fuel pump.

Thanks a lot BlackWorksInc. You were right. Changed the new Denso pump (it may well be a fake Denso even it looks very well constructed, like OEM) back to my original OEM pump after putting a new pump motor on it and that was the end of immediate zero pressure after turn off and no more occasional long cranks.

Question: problem in the pump allowing return into the tank is more likely localize at the junction of the pump and the plastic carcass where fuel line takes off? O-ring?
Thanks again.