Injector quits spraying after 2 seconds

[Donster]

Anne's 2.5 L TBI will shoot fuel for about 2 seconds, then stops
Replaced the injector with a known good one. Took Anne's injector and put it in Shanine's car and it runs.

All fluids are topped off and good, fuel pump works

Anyone have an idea where to start looking?

\D

[Fierofool]

The first 2 seconds of ignition ON is to pressurize the system.  The ECM turns off the pump and waits on the oil pressure sender to tell it that it has oil pressure.  Check the oil pressure sender. 

[Donster]

But even with the fuel pump shorted (12 volts on pin G) it displays the same symptoms.

\D

[Fierofool]

Are you saying the injector actually sprays fuel for 2 seconds when you first turn on the ignition?  Sounds like some wires are backwards if that's the case.  The injector should be closed until the ECM gets a signal from the control module that it's cranking, then it starts to pulse the injector.  It may be that circuit in the module has gone bad.  If you can pour fuel into it and make it run, then the other circuits are good. 

[Donster]

yes, it runs with starter fuid/fuel straight down the tube.

The weird thing is, my Hanes manual doesn't even tell me where the oil pressure sending unit is. Tells me about the V6, but not the 84-87 Duke.
Lee is heading over here with his big factory manual to figure this out.

I'll need to change the sender unit anyways, as I want to put the GT aux gauges in Anne's car, to get the 3 wire version, but first I need to find it!

\D

[Donster]

The next chapter of the mystery;
Lee Arnette found that 12 Volts were not getting to the brain box, therefore it wasn't sending the 5 Volts to the TPS, so the injector would only shoot and the engine would only crank sporadically.
Ignition module was good.
After we jumpered 12 V constant to the ECM, she would crank and run without issues. After about 20 minutes, the ECM started smoking. Put in another ECM and smoked it too. Conclusion is that we are dealing with a bad harness, which happens so often with the 84s.
Next step is to upgrade to an 85 or newer harness/distributor or maybe even go distributor-less.

More updates to come

BTW: Once it has an 85 or newer harness, the only thing remaining 1984 will be the chassis and the sail windows

\D

[Donster]

Update:

Broken fusible link for constant 12 V from battery to ECM.
Also detected that alternator is producing 52.3 V!!!
Fortunately, the link was broken or much more things than just the ECM would have fried.

\D

[Donster]

Final solution:

We are transplanting Anne's Duke and MY8 into the chassis of an 85 GT. Hence, it will still maintain most of it's uniqueness, it will just not have any of the 84 electrical disadvantages.
Also moving all of the exterior and interior over from the old car, i.e. rims, skins black dash, dark grey interior panels and so on.

\D

[Raydar]

Final solution:

We are transplanting Anne's Duke and MY8 into the chassis of an 85 GT. Hence, it will still maintain most of it's uniqueness, it will just not have any of the 84 electrical disadvantages.
...

A good move, IMHO.

[Donster]

Thanks Steve

Yeah, Anne was at first a bit depressed, as she really loved what all I had done to the car, but the electrical issues just kept multiplying to the point where it was no longer traceable or could be found by troubleshooting.
The donor car is in good shape and afterwards it'll still look the same as her 84, so all is good.

\D

[Fierofool]

Save all the aero stuff off the GT when you put the 84 panels on it.  My 86 has been lifted up by the rocker panels and they're cracked.  Save the 85 fender liners, too.  They will fit only the Indy, GT's, and 86/87 SE's. 

[Donster]

Donor car has all the panels on it, "except" the aero nose. It's identical to my (your former) 85, even red.

I plan on doing a rebody on Shanine's to make it look like a GT/SE with all the parts I pull off the donor

Do you need anything Charlie?

\D

[Donster]

UPDATE:

The Lil' 84 Dukie is no more!  Hauled of to the scrap jard yesterday.

But out of the ashes of her old 84 a new Fiero has been reborn. I'll probably start a new thread for it while The Duchess decides what she will name her new car.
I suggested "Midnight" or "Midnight Chrome" as it will be black metallic and has chrome rims
Maybe even "Midnight Phoenix", due to it being reborn?

Any other cool suggestions?

I will say this much though, I drove it today and it is AWESOME!

\D

[redraif]

Glad its up and running!  Did you save the duke or let it go with the body?  Anne said something about saving it to rebuild for Shanine if it was needed...

[Donster]

That is going to be my summer project:
Completely tear down the Duke and rebuild it, similar to what Topnotch did with his Duke

\D