Sorry, been asked a million times and I think I’ve read most of the threads at this point. Bought a 305 tpi IROC, 1987. Knew the fuel pump was out, changed that and changed the filter, the fuel line was badly rusted at the connection to the filter and sprung a leak, new fuel line from filter to engine.

car will run on starter fluid, I have 45ish psi pressure at the rail, injectors not firing. Injectors get 12V at the plugs, tried all of them, they all ohm out at a bit higher than 16. I put a noid light on and the light doesn’t light up at all when cranking, I know the light is good. No ground?

I am fairly certain it’s the ign module but hate to throw a part at the car without being fairly certain that’s it. From what I’ve read here I believe that is the next logical thing.


Little help?

 

You just ruled out ign module. If you have spark, it's fine. You need to troubleshoot to injector fire. Wiring, ecm, fuses, grounds. Those are places to look.

 

If the car has sat for any amount of time, the injs are probably gummed up and stuck shut. Either have them cleaned and flow tested or grab some new ones.

 

fuses are good, two inside and one by the battery. If the noid light doesn’t light up at all when I know I have power, that suggest no ground doesn’t it?

i appreciate the help.

 

Injectors get full time power, the ECM sends a grounding pulse signal to four injectors at a time to open them. What year car?

 

1987, 5.0, TPI

 

Welcome Aboard!

As previously mentioned, the ECM provides the ground path for the injectors to "fire" them. It could be helpful to inspect the engine harness ground connections at the rear of the right head/intake area.

Remove and inspect the INJ1 and INJ2 fuses in the interior fuse panel to verify the connections are clean and secure so they can actually pass the current necessary to operate the injectors.

It might also be helpful to disconnect the battery, expose the ECM (along the RH instrument panel above the passenger footwell) and disconnect the electrical connectors, inspect those for corrosion or contamination, and clean as necessary. Plug in and remove the connectors several times to help wipe the contact surfaces clean, then firmly connect and latch the plug back into place.

If the injectors do not fire after that, report back for further potential solutions.

 

Well, you don't have a security system, but you do have that 9th injector that shoots some fuel in the intake to start the motor. And I believe there are two circuits for the port injectors in the batch fired system. You're not getting any response from any of the three systems so the grounding would sure look to be the problem.

 

So, quick update. I’m tinkering with this thing when I have some time, not spending a ton of time on it.

earlier when I said it would run on starter fluid, that was true but I didn’t keep it running on it but for a second or two as it didn’t sound well. Yesterday I was checking grounds and everything looked fine………except for the plug wires on 2 and 4, those wires weren’t passing any electricity. Grabbed some wires, replaced just those two for now, plugged all the injectors back up except one which I put the noid light on. Cranked the car and the noid light blinked like it should.

sprayed a little starter fluid in and it started, sounded terrible, but started. The next thing will be to put new plugs in and pull the injectors and try to give them a cleaning.

I like to tinker.