Engine quits after some warm up (Page 1/2)
WonderBoy JAN 15, 07:52 AM
GM!
No not General Motors.
87GT 2.8
So yesterday morning (5 degrees fahrenheit) my usual routine, go outside and start the car to warm her up. Go back in pack snacks and make my coffee for the commute. 5-10 min I let the car warm up and idle. A mile away from home, Engine dies. No sputter, no gasping or misfiring. As if the key was turned off.

Tried plugging and unplugging connections I would think would be relevant. All fuses reseated. Nothing. First tow I've ever needed. 2hrs later the car is back in the driveway. Warmed myself up in the house for 30min, went outside and it started right up. Then 1-2min later engine quit WITHOUT visual or audible dying words. It will start again after this about 2 more times but engine will only run for 5/10sec.

No codes. SES lights up along with other idiot lights, and the fuel relay clicks behind me and I hear the pump prime the rail (45psi and then it dies down to zero in 20sec). Throughout my tests, when I let her sit an hour, to get it to start and run longer since the engines cold, fuel pressure is at about 41, then goes to 36 and creeps close to 38, then engine dies like the key got removed. The fuel pressure has mostly been like this for year's.

I've been up 24hrs+. Most all the posts and threads here about this same issue is brought up but those threads turn into dead ends and the resolution/fix was never posted. Fuel pump. Fuel Pressure Regulator. Check the vacuum lines. I did throw in a new Coolant temp sender below the thermostat housing (still assembly line original). Nope, no change. Now I did have at one point some fuel leakage that I resolved due to battery sliding and putting awkward pressure on the fuel feed/return lines to the rail. Wanted to clean up that mess and also check FPR. So I started taking apart the upper plenum. While I was in there, I've been meaning to put in some new injectors and throw in a new FPR diaphragm. New o-rings on everything that needed them. New gaskets.

After all this, the car has been sitting in the cold garage for 6hrs without it being turned our. Started right up. But after about 3min of purring like a kitten, dead.

On one of the threads (my head hurts, loss of sleep and reading and cold) something was mentioned about 300rpm on the tach when cranking. I don't get that, and was said to be ICM related. Gonna try that next. What sucks is, I have 3 including the original that I believe still works from when I got a brand new distributor. But they're in storage buried.

Also (oh please lord no) fuel pump pulsator could've come loose (others who bypassed with the submersible hose reported rupture/split). Dropped tank 1.5years ago and put in the pump gm model that came with the 88 2.8. along with cleaning the sending unit.

This is the start of day2 of calling out without my beloved wheels. Any other ideas as to why this is happening?
😴 Time.

Curtis

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Curtis

1987 Pontiac Fiero GT:
<Drives like a Go-Kart, handles like a roller coaster>

fierosound JAN 15, 08:31 AM
Had a friend with exact same problem.
Engine would just "shut off" after 10 minutes.
Would start and run fine at next "cold start".

Problem turned out to be the pickup coil in distributor.
Test it with a multi-meter the next time engine shuts off.
It's a $10 part.

PDF Service Manuals and more https://fieroinfo.com/




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My World of Wheels Winners (Click on links below)

3.4L Supercharged 87 GT and Super Duty 4 Indy #163

[This message has been edited by fierosound (edited 01-15-2025).]

Dennis LaGrua JAN 15, 11:57 AM
Without seeing the engine I'll go along with an ignition problem. First step, test for codes, then spark. If Ok then test for fuel pressure. I would also not recommend using an original 38 yr old classic vehicle as a daily driver.

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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 "

WonderBoy JAN 15, 01:04 PM

quote
Originally posted by fierosound:

Had a friend with exact same problem.
Engine would just "shut off" after 10 minutes.
Would start and run fine at next "cold start".

Problem turned out to be the pickup coil in distributor.
Test it with a multi-meter the next time engine shuts off.
It's a $10 part.

PDF Service Manuals and more https://fieroinfo.com/





Step 1 Result:
Infinity from distributor housing ground or chassis ground, both pins from the pickup coil
Step 2 Result:
880Ohms consistent

quote
Originally posted by Dennis LaGrua:
Without seeing the engine I'll go along with an ignition problem. First step, test for codes, then spark. If Ok then test for fuel pressure. I would also not recommend using an original 38 yr old classic vehicle as a daily driver.



Purrty ain't it? I take good care of her. As much as I love my Fiero purchased in late 1998, it's all I got Sir. And with the a** r*ping we've been getting these last 4 years it's not an option at the moment or for a few years. It is on my wish list. I don't put myself in unnecessary debt. If you know Gavin Newsom, Volodymyr Zelenskyy or Benjamin Netanyahu, tell them to buy me one, because they sure are living it up off my hard labor. Maybe a "transportation bailout", like the college tuition bailout scam.
WonderBoy JAN 15, 01:07 PM
Gonna let it sit again for 30-60min, but this time I'm gonna try firing it up jumper'd in DIAG mode and see what she does.

It's never done this and the last few days are the only times it's stayed in single digits, even though last year no problem. Gonna try and get a cheep spark checker once a relative is available to see if spark is there after it decides not to fire anymore until totally cold. I do have the extra "add-on" heatsink installed on the CARDONE 841633 distributor that I did as a preventative measure when I installed it 3years ago.

[This message has been edited by WonderBoy (edited 01-15-2025).]

Vintage-Nut JAN 15, 01:11 PM

quote
fierosound:
Problem turned out to be the pickup coil in distributor.
Test it with a multi-meter the next time engine shuts off.



When you test the pickup coil; clean the connectors on both the coil and in the ICM.

Perhaps 'it' is a weak connection: No Pickup Coil Signal - No Injectors

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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

WonderBoy JAN 15, 01:27 PM

quote
Originally posted by Vintage-Nut:


When you test the pickup coil; clean the connectors on both the coil and in the ICM.

Perhaps 'it' is a weak connection: No Pickup Coil Signal - No Injectors



One thing I didn't do was check the connection harness near the thermostat where the flat wire assembly is that goes across the back side of the valve cover toward the ignition coil under the intake plenum. That is untouched from factory. Ugh
WonderBoy JAN 15, 01:32 PM
Exhaust flows nice a freely from what I can see in this cold weather, so don't think it's the clogged catalytic convert. Does burn oil a bit due to valve seals and 2 cylinders with 120psi compression.

Edit:
Diag mode, same result: 30-60 second run time

[This message has been edited by WonderBoy (edited 01-15-2025).]

Vintage-Nut JAN 15, 02:35 PM
Spark?
WonderBoy JAN 15, 02:47 PM

quote
Originally posted by Vintage-Nut:

Spark?


Still wait to get a ride to the local Advance Auto for inline checker and second person availability. Do you think it's a heat thing causing some minor connection to fail when a close by connection point (point of failure) gets warm causing a disconnect of sorts? Possible...

I've had this issue in houses with electrical outlets close to main outside doors during winter preventing other receptacles in the circuit/room from working due to tight wires tacked to the studs. Cool flex.