1984 Iron Duke crank/no start (Page 1/1)
Lostpuppy1962 SEP 23, 02:58 PM
Drive home, (lost power) for a (split second) when about to shift from 3-4th, continued home.
At home, turned key, (started), let off key, it (about 3 seconds) dies.

Before all the step by step diagnosing.

What is a first gut thought about the above description? Because you guys know Fiero's, Thank you.
Dennis LaGrua SEP 24, 08:19 AM
Getting down to basics a no start condition is usually a fuel or ignition problem or a loss of a power connection. There is no way to tell unless you go through the checks for the ignition and fuel supply. Check for trouble codes, spark and fuel pressure and go from there. Your vehicle is 41 years old and anything could have gone wrong. Most likely a fuel pump, coil , or ignition module is the problem. .

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Lostpuppy1962 SEP 24, 09:41 AM
So, I had assumed that when the key is turned, that the fuel pump runs about 2 seconds (it does) it was good.
I thought it turned on and then shut off when the correct pressure was ready to run.

I replaced the the distributer cap and rotor as the original had grooves worn in.
A little starting fluid would get it to (pretend) to fire.
I replaced the fuel filter. I also replaced fuel cap as it's seal was messed up.
Now for the fun I guess.

[This message has been edited by Lostpuppy1962 (edited 09-24-2025).]

Fierology SEP 24, 11:20 AM
I agree with Dennis regarding steps to take. I have an 84 as well. For what it's worth not being there with the car, my gut says fuel delivery.

Some thoughts- How's power under load? It would be helpful if you can test fuel pressure. Different behavior hot vs cold? Different behavior on full tank? -...half, quarter or lower? Maybe fuel pickup at in-tank pump is misbehaving. You should be able to locate the fuel pump wire by firewall - how's its condition? Is fuel fairly fresh?

-Michael

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He who dies with the most toys... still dies.

Lostpuppy1962 OCT 03, 05:09 PM
No codes, just the 12, but the battery had just been disconnected and then reconnected. Replaced distributor cap and rotor. It will attempt to fire/start with starting fluid or a little gas in the throttle body. Tachometer comes up and twitches between 200-400rpms. Fuel pump hums when key is turned on.
Replaced fuel filter. With line disconnected before the filter I pulled fuel through the line with a siphon pump. With the line disconnected and cranking engine for 15-20sec no fuel comes out.
Anything else to check before I drop the tank?
Patrick OCT 03, 06:16 PM

quote
Originally posted by Lostpuppy1962:

So, I had assumed that when the key is turned, that the fuel pump runs about 2 seconds (it does) it was good.
I thought it turned on and then shut off when the correct pressure was ready to run.



The fuel pump simply runs in that situation for two seconds... pressure or no pressure.


quote
Originally posted by Lostpuppy1962:

With the line disconnected and cranking engine for 15-20sec no fuel comes out.



In the unlikely chance it's a bad relay, connect 12v to the fuel pump terminal of the ALDL port. This bypasses the relay.



If the pump runs, and there's no fuel pressure, the flexible hose in the tank has probably rotted/ruptured.
Dennis LaGrua OCT 03, 10:49 PM
Most fuel pumps can't last 41 years. If the pump has been replaced by a new reliable brand some mechanics forget to use J30R10 submersible fuel injection hose to attach the pump to the gas line in the tank. Over time regular J30R9 fuel injection hose deteriorates and so do pumps. Check your fuel pressure.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Lostpuppy1962 OCT 13, 08:46 PM
Gas gauge said 1/2 tank. Added a little over a gallon. Sprayed starter fluid. Started car and took care of tools and working after dark light. Went to station and put in a little over 7 gallons.
Patrick OCT 13, 08:54 PM

quote
Originally posted by Lostpuppy1962:

What is a first gut thought about the above description? Because you guys know Fiero's, Thank you.



Well, we don't usually ask if there's enough gas in the tank... but I guess we should. lol
Lostpuppy1962 OCT 14, 02:29 PM
Well, the gas guage said 1/2 tank and it has always worked, oh well.
Thank you all for your efforts.