Fuel pump question.

[TopDollar69]

Is my 85 Lebaron supposed to maintain pressure in the fuel rail after the car is shut off? After doing some testing tonight, I've determined my car does not maintain pressure in the rail unless I pinch off the return line just as I turn the car off. Is there supposed to be a check valve in the fuel pressure regulator, or perhaps in the sending unit? I don't understand how the return line can return fuel to the tank while the pump is running, but it's supposed to hold pressure while the pump isn't running. Any info on how this works would be appreciated.

[csomni]

yes its supose to maintain psi after its shut off. sounds like a bad fpr. the fpr has a spring in it so when the fuel psi reaches a set point it starts to return fuel to the tank. when you shut the car off the psi drops and the spring psi closes the needle valve. so aparently the needle valve is not sealing. there is a check valve in the pump in the tank that keeps fuel from returning. and the injectors should not leak when car is shut off. i hope this helps. when you replace it cut open the old one to see how it works