RamboSmurf

Please help with Fuel Pump electrical problem. I have a 83 280ZX, 5spd. When you turn on ignition sometimes the fuel pump will turn on and run for its 5 secs then stop. The car will start and run fine for a while then shut off. There is no consistency as to when it will do this.
When trying to restart I can see that the juice will go to the fuel pump for a split second and shut off (done via test light). Ignition off then on and It will stay this while until it gets a wild hair up its A** and then juice will flow to the pump as it should again. This time period can be minutes, hours or days later.
I have checked every switch, valve, sensor there is. Replaced all relays, fuel pump, cleaned every ground and hot wire. Ran every test in manuals. Doesn't matter what I do....same thing occurs. Followed every test min FSM - no answer. Not the ignition switch as its been tested over and over.
I have even by-passed the ECU and direct wired the fuel pump to turn on when ignition switch goes on, but it will not start that way....only when the pump turns on the way it should.
I have spark at all times, so I have ruled out the no spark, no fuel pump rule.
I am totally stumped at this point.
I am leaning toward ECU, but would value some other opinions before I replace that.
Also can you use a Auto ECU from a 83 in this car as its a standard?
Please help as I love the car but its almost ready for 5 gallons of gas and a match!!!
Thanks
RS

WildmaN

Welcome to Zdriver bro'. The only information I can give you, is about the ECU. I have read on here. That you can use an Auto ECU for a 5 speed. And considering it is from an' 83. Is yours a digital dash or analog? And the same question goes for the Auto ECU. I'm not entirely sure if that matters. (with the digital or analog) That is really all I can give you. Hopefully someone else on here, with more knowledge. Can help you some more. So have you replaced the fuel pump itself?

RamboSmurf

Thanks much. I can get a Auto ECU. I changed the pump..now I got 2 good ones. I hooked a test light up to the fuel pump connection near the seat and it flashes on for about 1/2 second then goes off....except sometimes it will stay on..then the fuel pump works fine..car starts and works fine...runs for a while.. then dies.

WildmaN

Hmm...how about your ignition control module? Did you test that? I have heard of that causing the car to shut off at random times, when it gets hot. Anyway that is located on the side of your dizzy. Oh, and you are quite welcome.

RamboSmurf

I did the tach test while cranking to see if the needle bounced and it does, plus I have spark. I can't do the other test's yet because I can't get the thing to run long enough now to reach operating temp. I'm gonna have to try the last 3 tests on a cold dizzy. I tried everything else so its sure worth a shot. I know when I do find it, I'm gonna feel like a jerk because its gonna be something simple that I overlooked. Again, thanks.
RS

BlueKitsune

Whats your Oil Pressure? That can shut off the engine if the pressure is too low for too long. make sure to check that out too for bad wiring/connection

RamboSmurf

I clean the oil pressure off as it was filthy. The pressure is low at idle but jumps up over 1500 rpms. Now it won't start half the time to check it.
Problem is I don't know if I can use a jumper wire to bypass some of these switches to rule them out.
Today I'm gonna re-try the clutch switch and EFI relays again (like keep checking for those lost keys in the same area hoping they go back there)

RamboSmurf

ECU!!!! Changed it and problem gone. Thanks to all for the help. Now the car is safe from fire damage.