76 280z wont start..

[gpchris]

Well after playing with it for a while i found it it wasnt getting any fuel... The injectors arent getting a signal and neither is the pump. Seems like the entire fuel injection circuit is killed somehow.. I was thinking the pcm may have gotten unplugged or screwed up but the pcm doesnt control the fuel pump does it? Only the AFM controls the fuel pump right? Have any ideas guys?

[Zcar78]

The fuel injection relay plays a big part in providing power to most of the fuel injection components. The F.I. relay provides power to the control unit, fuel injectors, and AFM. It also provides power to the fuel pump and aux air regulator when the ignition switch is in the "start" position. After the engine starts, the fuel pump gets it's power through the AFM when the ign sw is in the "on" position.

Disconnect the starter solenoid lead so the engine will not start. Turn ign sw to "start". Listen for pump to run and the pressure regulator to buzz. If no sound, then it may be the relay. Check relay by placing hand on relay when in "start" position and feel for click. If no click, then check ign sw.

Hope this helps

Randy

[sblake01]

Start by reading this, especially the EF section:

http://www.xenons30.com/files/FSM/76_datsun_280z.zip

[gpchris]

Well i changed the pcm hoping that would fix it.. Now im getting a positive feed to both pins on the injectors at all times (even with the key out!). What the hells going on here?

[sblake01]

There is no PCM (Powertrain Control Module) in a 76 or any other 280z. You changed out the ECU and I think Nissan was over-descriptive in calling them that! Pardon my digression. Did you use an ECU that is compatible with your vehicle?

[gpchris]

yeah i replaced the ecu.. I replaced it with the same one.. This makes no sense. Why is there a constant positive feed to both pins on the injectors? Somethings seriously screwed up here.

[sblake01]

Was this problem there before the ECU change? Sounds like there has to be a short of some kind. Have you done any of the pinout tests shown in the FSM?

[gpchris]

Was this problem there before the ECU change? Sounds like there has to be a short of some kind. Have you done any of the pinout tests shown in the FSM?

Well before for some reason i had both wires for the pcm hooked to the + side of the battery. Then when i corrected it it still didnt work so i assumed i screwed it up. Thats why i replaced it.. But with the new one wired up correctly i got a + feed on BOTH injector pins.. where before i didnt get power to any of them..

I havent tested anything yet.. it all seems so confusing..

[gpchris]

ok after playing with it for a while and doing the tests in the book i found that there was a problem at the relay. I ended up switching the plugs on the relay and now it runs great! I did **** up the original pcm but this ones good.. I just wired the relay up wrong this time.

[sblake01]

Glad you found it because that's a problem I've never come across.