77' 280z low fuel pressure

[antsorce]

I'll give a little background on what she's doing and what I've done. car runs great cold but when it reaches normal operating temp the idle gets rough, (sounds like it has a cam but, i'm certain it doesn't) and it's hard to take off from a stop unless you coax up the rpm's a bit. (it also stumbles when cruising at low rpm's).

I did the entire EFI system check through the ECU bus as per the fuel injection bible. The only item that didn't check out was the water temp sensor which i replaced but saw little to no improvment in the cars performance.

next did a fuel pressure check and found it only to be running at about 20psi and not holding pressure. bad check valve in pump was the reason for not holding pressure. replaced pump holds pressure now (starts alot faster) but still low fuel pressure. then replaced fuel pressure regulator but still no improvement.

so the only other two possible fuel delivery culprits i can think of are something in the tank itself or could the fuel dampner be restricting fuel flow. can i bypass the dampner just to do a pressure check or will it adversly affect something else. any ideas would be greatly appreciated.

the car is completely stock except for a cold air intake, header, and exhaust. I realize ive probly lost some low end because of this but it doesn't explain the low fuel pressure right?

[webdawg1]

You did not mention anything related to the fuel filter up in the engine compartment...How long has it been in the car..?? Could very well have some "Crud" in the fuel tank also...would probably start with the fuel filter first tho...and see how much difference it makes...after it is installed...

webdawg1

[antsorce]

fuel filter was one of the first things I replaced when i bought the car 3 years ago. the car only gets driven in the summer here in milwaukee so theres limited miles on the filter. should be fine.

[IdahoKidd]

the car only gets driven in the summer here in milwaukee so theres limited miles on the filter. should be fine.

Absolutely untrue! Because of that very driving the fuel filter is definately suspect. The tanks in these cars get filled with crud and with the poor fuel available today, they get even worse. Letting it set for any length of time doesn't help. If changing the fuel filter out doesn't help, remove the cover in the hatch and take out the fuel gauge sending unit and look in with a flashlight. It will break your heart. I guess I am saying not to over look the obvious by assuming the fuel filter is good. I simply may not be.

[antsorce]

fair enough, i'll toss in a new filter and see where i'm at.

[ronroyboy]

I had same problem . I istalled a new pump, pressure regulator, fuel injector seals, fuel filter, hoses. but it was a dirty screen in the new fuel pump. Had the tank cleaned and lined at radiador shop and installed inline filter between pump and tank. Runs like new again.