Fuel Pressure Not Holding

[summs]

I recently just did a fuel pressure test on my 02 Explorer and when the engine is running the pressure is fine but as soon as I turn the engine off the pressure drops almost immediately to zero. What is the most likely reason for this? From what I can guess the fuel pressure regulator (which is in the sending unit in the actual tank) has some sort of valve that is supposed to close when the engine is off to hold pressure and it’s not closing and I need to replace the entire pump and sending unit. Am I on the right track? I don’t think it’s a leaking injector because it doesn’t smell like gas and the pressure drops so quickly. Plus it starts hard when the engine is cold but not once it’s been warmed up some.

 

[Mbrooks420]

It’s a check valve that allows one way flow, it doesn’t open and close with the motor.

 

[summs]

It’s a check valve that allows one way flow, it doesn’t open and close with the motor.

Ok so if the check valve is failing then in would lose pressure correct?

 

[Mbrooks420]

Ok so if the check valve is failing then in would lose pressure correct?

Indeed.

 

[Mbrooks420]

Sometimes the rubber fuel hose in the tank ruptures and will cause this also.

 

[summs]

Sometimes the rubber fuel hose in the tank ruptures and will cause this also.

What does the rubber fuel hose connect to from inside the tank? Is it for the filler neck or connect one of the gas lines?

 

[Mbrooks420]

Between pump and sending unit. Maybe the regulator. I’m not terribly familiar with the third gens.