'86 GT Won't start, help!

[GTRS Fiero]

Any progress?

[Cyb3rw0lf]

Yes there has been some.... Much to my embarrassment it's a timing issue as I did not realize this crank has three timing marks on it. I'm now on the largest of the three but believe it to be 180 degrees off. I'll work on it this afternoon and update with results.

[GTRS Fiero]

Hey, it happens.  Looking forward to the results.

[Cyb3rw0lf]

Timing is now set properly and the car will run temporarily when fuel is introduced to the throttle body but not otherwise. I've double checked everything from the pump up to the injectors and it was all OK until I checked if the injectors were getting a ground signal from the ECM to fire, which they are not. Any advice on where to move on from there? I checked the ECM grounds and found that they had voltage to them when attempting to start, but am unsure if its simply a change in resistance.

[GTRS Fiero]

So, it was getting fuel with the wrong timing, but not with the right timing?  Is the fuel pump still running?  We're back to checking for fuel pressure, or bad injectors.

[Roger]

Old fuel filter? Engine block has good ground?

Please see our 'Tech Tips' for the proper timing procedure. Use the center mark on the balancer to set your timing.

[Cyb3rw0lf]

We assumed it was getting fuel due to wet plugs, apparently not so though. Fuel pump is good and runs, block has good ground and the fuel filter is new. As I said I currently have no pulsing ground signal to the injectors from the ECM so I don't know if they function or not, going to attempt grounding D15 & D16 from the ECM manually to check if the injectors fire, if so then it should be a wiring problem I believe.

Timing is now correct as per the GAfiero tech tips, which is also how I realized my timing mark problem.

[Cyb3rw0lf]

I should also note that this vehicle had various electrical uh.... "Modifications" that I've been working on restoring to the original configuration, at this point I think I've gotten them all but perhaps I missed one.

[Cyb3rw0lf]

Injectors fire when manually grounded and attempting to start, the car even ran (horribly) for a few moments before the screwy fuel/air ratio shut it down.

Bad ECM or perhaps whatever sensors the ECM uses to control the fuel timing?

[GTRS Fiero]

Current summary:
1. Timing is supposedly now correct
2. Injectors, ICM, ignition coil, pickup coil, rotor, cap, plugs, wires, fuel filter, fuel pump, FPR have been replaced
3. Engine grounds are good
4. Engine runs when starter fluid is sprayed into the intake
5. Engine runs badly briefly when injectors are grounded manually
6. The injectors do fire
7. The plugs were wet before timing was changed
8. The injector bank fuses were checked

I almost suspect either bad grounds or bad fuses.  When you spray fuel into the throttle body, do you remove the intake hose?  Just to get a baseline, are you doing the same thing as when manually grounding the injectors?

I don't remember.  Did you replace the MAP sensor?  I had to unplug mine and limp home, in another vehicle.  I don't remember what the symptoms were, but running terribly.

Hmmm.  Did you check/replace the IAC, and CTS?  You didn't adjust that screw in the throttle body by the IAC, did you?

[GTRS Fiero]

You can check the IAC like this

[Cyb3rw0lf]

The problem has been found!

Decided to go back to basics and ignore what my helper and I have seen to this point, worked through everything before finally pulling the injectors that we had "cleaned" and attempting to put pressure through them independently with poor results. So poor in fact that these injectors are done for and need replaced, before I go about this though I've seen several mentions online of replacing the stock injectors with those from other vehicles. Is there a particular reason for this besides performance? I'm mostly going for the best fuel mileage I can get at the moment.

[Fierofool]

With the stock 86 ECM, it may not be able to efficiently operate some aftermarket or even GM factory injectors.  Especially the MulTec style injectors.  I would suggest that you go to a fuel injector sales and repair company and tell them you want 15# Pintel-style injectors.  Give them the part number of your old injector as a cross-reference.  I like these guys.  They have been Fiero owners/racers. 

https://fuelinjectorconnection.com/shop

[GTRS Fiero]

I'm glad you're making progress.  I was wondering...

[Cyb3rw0lf]

Thankfully all of this chasing problems around has led to my replacing most other things that could go wrong in the future and lots of spares.