98 S70 fuel pressure at the rail

1998s70 · Post by **1998s70** » 05 Nov 2014, 06:13

When relieving the fuel pressure at the fuel rail (shrader valve) I noticed that there was no pressure. This was after the car had been sitting for over 12 hours. It starts and runs fine.

Does the fuel normally bleed back through the pump to the tank, or do I possibly have a leaking injector?

Should the fuel pressure remain in the fuel rail even though the car has not run for a length of time?

Thank you.

DrJammer · Post by **DrJammer** » 05 Nov 2014, 09:08

Doesn't seem like a problem, the rail should hold pressure for some time after the car is off and will eventually go to zero if off long enough.

I do not know the timing, but your rail should not drop to zero right away.

do a quick search of fuel pressure or check valve or fuel pump or fuel pump relay and you will find plenty of reading on this

Post by **Ozark Lee** » 05 Nov 2014, 19:37

Is the car starting real hard? If not then things are probably fine. The fuel pressure test has minimum pressures after time but the test period only goes for something like 20 minutes. That said, I typically have a fair amount of pressure at the rail after the car has been parked for a day or two.

...Lee

1998s70 · Post by **1998s70** » 05 Nov 2014, 19:48

It starts right up, even after sitting for several days. I read something about fuel pressure bleeding back through the fuel pump, so maybe it has something to do with that.

Post by **Ozark Lee** » 05 Nov 2014, 19:52

There is a check valve in the fuel pump housing that is supposed to hold the pressure but they can fail to one extent or the other. When they completely crap out the car can be a real bear to start in the morning. Since your car starts OK I wouldn't worry about it.

...Lee