84 Iron Duke Injector/Ignition Issues (Page 1/1)
pross4627 SEP 26, 08:37 PM
I have a 1984 Fiero with the iron duke and it cranks but won’t start. It gets good compression, spark (tested both plugs and wires), but the injector isn’t getting any power. The injector itself works (tested with 9-volt battery) and when I removed the fuel line from the TBI there was fuel there. I haven’t tested fuel pressure yet, but the pump, filter, and rubber lines are brand new (I will be testing pressure tomorrow just to rule that out). I have also replaced the distributor, ignition coil, and ignition control module (ICM and coil both tested bad). The fuses in the fuse box under the dash are all good as well. I personally think that there are issues with the wiring as there are some pretty shadetree things with it that I have had to fix (does anyone make/sell wiring harnesses for the 84 iron duke?). Does anyone have any ideas or other tests I could do to get it running? I am also confident it is not the ECM because the tach sits at 400 rpm while cranking. Tomorrow, other than testing the fuel pressure, I will also be testing the ignition coil and control module again to see if they are bad.
theogre SEP 26, 09:29 PM
ECM won't turn on injector w/o seeing ignition...

ECM turn on by grounding the injector. Injector should have "12v" anytime the I-key is On.
Get a Noid Light to test the wiring etc.

If ignition is good... then maybe ECM is "dead."
1 crack solder joint is enough to "kill" a ECM that seems to work otherwise.

If "dead" need the PROM in it to use w/ new unit.
Also See my Cave, ECM Heat

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

pross4627 SEP 27, 07:55 PM
Thank you for your quick response.

I tested the wires around the distributor and ignition coil and they are both good(coil, control module, and all the wires going between them). However, there is no power going to the distributor when in the key on or while cranking. I haven't gotten around to tracing it further back, but I hopefully will tomorrow.

Fuel pressure read zero so I tested the power to the fuel pump and there was nothing, once again both key on and while cranking. I did forget to test the ground. I believe the relay is good as there is a click when the fuel pump should turn on (would any other relays click in the key on position; the car has ac if that matters). The fuel pump fuse was blown when I checked it. This leads me to believe that there are issues with the wiring, which will be checked tomorrow as well.

I would also like to test the fusible links, but I have not been able to find any methods to test them, so how would I go about doing that?
theogre SEP 27, 11:48 PM
there is no real testing for fuse links.

When "bad" they often Blow and Very Obvious because insulation Burns in a controlled way.

If you want to test...
Find connections on wires w/ the link.
Do Not test a link directly like pierce the insulation in any way.

Two links go to Starter and often rot... Carefully pull on links & wires. Wires should not let you pull at all. If rotted then insulation will stretch, link "rubber" often a lot more then normal plastic. Normal plastic often will swell because wire rot like steel rust make wire to "Grow" inside of insulation.

See my Cave, Wire Service
edfiero SEP 28, 11:07 AM
My fusible links went out twice in the last 35 years. Both times they went while driving. So from my limited experience I'd say unlikely to be the links if car was running fine when you turned the key off.
pross4627 SEP 28, 08:50 PM
Thanks again for the quick responses.

I didn't get much done today as school takes priority, but here's what I managed to do:

1. The fusible links are all still good.
2. The battery cables do not show any signs of rubbing on the water pump pulley or belt.
3. The wires and connectors leading to the fuel pump are good.
4. Another fuse blew while I was bypassing the fuel pump relay through the ALDL port, but still no power to the fuel pump.

I also found the wiring diagram for the fuel control system so I will be able to test the all of the wires in that system tomorrow.

If the ECM turns out to be bad, would I be able to replace it with one from an 85 GT, as long as I change the PROM? Or would I need to get a new one?
olejoedad SEP 30, 09:02 AM
The 85 GT ECU will not work, you need one from an 84.

The attached chart will help you.
pross4627 SEP 30, 07:33 PM
Thank you all for all your help. Today I managed to get it running smoothly just in time for the one year I've owned it. Turns out the ground going to the fuel tank had some kind of break so it would occasionally be grounded and sometimes not. I replaced the wire and put the tank back in and it runs great.
olejoedad SEP 30, 10:58 PM
👍🏼👍🏼

Now, go and enjoy it!