86 GT Int. No Start, Running Poorly (Page 1/1)
UP86GT MAY 26, 12:06 PM
Hello all, first post though I've been browsing awhile. I just picked up a 86 GT a couple weeks ago that has been sitting for probably 3 years. I knew the car back when it was driving around last and I filled the tank with non ethanol 91 octane (had around a half tank of old fuel in it) and it fired up and ran pretty reasonably. Here and there would get a miss/pulsating feeling cruising around 2500 rpm but then would go back to running fine. I probably put around 200 miles on it and new spark plugs and air filter but thats it so far. Then things went downhill.

A couple days ago it was running a little crappier than normal. it started holding high idle and would seem to idle but break up under throttle and also earlier in the day when it was first started it ran horribly for about 2-3 minutes then was back to fine again. Ive been trying to get fresh fuel through it and I was maybe around a half tank and dumped in a bottle of STP injector cleaner in then topped it off again with 91 non ethanol. Went to start it after filling, people were checking the car out at the pump so of course the most embarrassing time I get nothing but cranking, no start. First time I have had it happen. I pushed the car out of the way, luckily its light, then moved some wires and plugs around and still nothing. After maybe 10-15 minutes or so it fired back up but ran crappy.

Right before I had this happen it started idling high, like 2000-2200 rpm and when I went to give throttle it was breaking up barely running but once I got moving seemed to do a little better then got me back home about 10 miles away. I parked it before pulling in the garage. 10 minutes later it wouldn’t start again to move it. When it finally did I had to hold throttle pedal like half to wide open to get it to move but it wasn’t revving up nearly like it should of been and was smoking bad.

I haven’t tried it since then. I feel like it might start right up like nothing happened or it might not. I did do a code scan and got codes 12, 15, 32. 12 I guess your always supposed to get, 15 ECM Coolant temp sensor circuit, 32 EGR system.

Now I am mainly wondering where to start? How can I tell if this is fuel or spark related and also wondering if the codes have anything to do with it or not? My main worry now is getting stranded with it as it almost happened and I was pushing it to get it home.

Any help is greatly appreciated and I will try to keep searching. Loving the information I am finding on this site!


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1986 Fiero GT
2.8 V6 4 Speed
176k+ Miles

robmox MAY 26, 05:12 PM

quote
Originally posted by UP86GT:

Hello all, first post though I've been browsing awhile. I just picked up a 86 GT a couple weeks ago that has been sitting for probably 3 years. I knew the car back when it was driving around last and I filled the tank with non ethanol 91 octane (had around a half tank of old fuel in it) and it fired up and ran pretty reasonably. Here and there would get a miss/pulsating feeling cruising around 2500 rpm but then would go back to running fine. I probably put around 200 miles on it and new spark plugs and air filter but thats it so far. Then things went downhill.

A couple days ago it was running a little crappier than normal. it started holding high idle and would seem to idle but break up under throttle and also earlier in the day when it was first started it ran horribly for about 2-3 minutes then was back to fine again. Ive been trying to get fresh fuel through it and I was maybe around a half tank and dumped in a bottle of STP injector cleaner in then topped it off again with 91 non ethanol. Went to start it after filling, people were checking the car out at the pump so of course the most embarrassing time I get nothing but cranking, no start. First time I have had it happen. I pushed the car out of the way, luckily its light, then moved some wires and plugs around and still nothing. After maybe 10-15 minutes or so it fired back up but ran crappy.

Right before I had this happen it started idling high, like 2000-2200 rpm and when I went to give throttle it was breaking up barely running but once I got moving seemed to do a little better then got me back home about 10 miles away. I parked it before pulling in the garage. 10 minutes later it wouldn’t start again to move it. When it finally did I had to hold throttle pedal like half to wide open to get it to move but it wasn’t revving up nearly like it should of been and was smoking bad.

I haven’t tried it since then. I feel like it might start right up like nothing happened or it might not. I did do a code scan and got codes 12, 15, 32. 12 I guess your always supposed to get, 15 ECM Coolant temp sensor circuit, 32 EGR system.

Now I am mainly wondering where to start? How can I tell if this is fuel or spark related and also wondering if the codes have anything to do with it or not? My main worry now is getting stranded with it as it almost happened and I was pushing it to get it home.

Any help is greatly appreciated and I will try to keep searching. Loving the information I am finding on this site!




To me, this sounds like a fuel issue. However, spark would be incredibly easy to test. Just hook up a spark plug light and see if you're getting spark to your plugs. Cost should be like $10, and shouldn't take more than a few minutes and a friend.

The best advice when diagnosing an issue, is to start with the cheapest and eliminate each on your way through the system. Before the fuel system, start with the EGR. EGR systems get crazy carbon build up. See if you can pull your EGR tube and clean it and see if that helps. Neither of these issues would cause the high idle, but I did find that when I changed my air filter, my idle went from 1100 rpms to 1500.
theogre MAY 26, 07:24 PM
Hard to narrow down for long post... Examples:
If has spark, Doesn't mean ECM sees that... ECM w/ bad wires to Ignition or even bad ECM won't turn On fuel injection & No Start.
See my Cave, HE Ignition & Ground "Myth" notes

Bad plug wires, coil, etc can "break up" at higher RPM but idle ok.

ECM can have heat problems too and may seem to work but is dead. See my Cave, ECM Heat Even cold ECM can have weak solder joints that open when cold and does same.

Iffy IAC motor and more can cause a No Start as well cold or hot engine or both.

EGR is control by ECM for V6 and likely control valve is bad at minimum. EGR and its tube like to leak too cause crap idle or no start.
See my Cave, Vac Leaks

So you need to dig more to find real problem(s).

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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

Patrick MAY 26, 09:52 PM

You may have multiple issues.

The ICM is notorious for failing. If your tach doesn't move while cranking the engine over, suspect the ICM. However, before replacing it, disconnect all the wiring harnesses plugged into the distributor, and then take the distributor cap off and disconnect the pickup coil. And now plug everything back together again. Why? Because sometimes it's just a corroded connection that mimics a bad ICM.

If you go through all that and the tach still doesn't twitch while cranking, replace the ICM, preferably with an ACDelco unit. And use proper thermal compound between the base of the distributor and the ICM.
UP86GT JUN 01, 09:51 AM
Sorry for the delay in response. I really appreciate the help and may need to really depend on this car shortly. I haven’t got to work on it yet but will check out the EGR tube situation.

I think it was 2 days after the initial no start and barely running enough to get in the garage to park I just went out and gave it another try. Fired up like nothing happened and ran pretty well. A little up and down on the idle intermittently, hunting around a bit but did not start running bad, misfiring etc like it was or idle 2k plus like it was. I have drove it a couple times since then. Today I am going to try to bring it to get an inspection and hopefully that goes well.

I did notice the day it wasn’t starting the tachometer DID move even with the no start. I am going to look into putting a new fuel filter on and changing the oil as well since that hasn’t been done yet. May also pick up wires, cap, rotor and coil even though funds are tight right now. I don’t think they should be that much.

Edit: Probably $150 or so in parts for everything above so might go that direction.

Thanks again everyone!

[This message has been edited by UP86GT (edited 06-01-2022).]

Forrest JUN 01, 10:39 AM
I do not think anyone had mentioned it yet but have you swapped the fuel filter? It has been an issue on my 86 and my sons 88. Sitting for a while then driven...stuff brakes loose in the tank getting sloshed around then plugs it up. Car stops...crap settles...runs fine...so forth and so on. Its a $13 part and takes 10 min to swap. Give er a go.
UP86GT JUN 05, 10:24 PM
Just an update. I have changed the fuel filter and ran it about 100-120 miles since last night. I have not had it run poorly or feel the misfiring, pulsating feeling when cruising under load at 2500 RPM or so like before. I am hoping for the best of course!

I still have to get the oil changed ASAP and plan to do the cap, rotor, coil and wires in the next week or two hopefully. Also want to check out the EGR and coolant sensor codes more if I get the time. I have been researching them more on here. I’m going to drive it to work this week at least 40-50 miles a day so I should know soon if the main problem is solved, unless it is really intermittent.

Thanks again for the help everyone!

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1986 Fiero GT
2.8 V6 4 Speed
176k+ Miles