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| Intermittent No-Start Issue (Page 1/3) |
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PatrickTRoof
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JAN 20, 02:35 PM
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Lately my 1985 GT 2.8 has developed a random no-start issue which acts like a bad ICM (no spark or tach signal). Sometimes it will do it on a cold start, other times if the engine has already been running.
At first I thought I was eating up ICMs for some reason, but then sometimes it will then start up again. I've even seen it crank for a second with no tach signal, then suddenly catch and fire right up. Sometimes
I've fixed it by swapping in a known good ICM, which will fix the problem until next time, but I've swapped in ICMs which I had thought were bad from a previous case of this happening, and it fired right up. And once
it's running, it never cuts out. The only thing I can think of is it might be the 2 wire connector between the coil and the ICM. The ignition coil and pickup coil are only a few months old. As noted above, the ICM is
one of a few new or good ones I've put in it recently.
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theogre
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JAN 20, 02:52 PM
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ECM won't run EFI is has ignition problems or just "think so."
See my Cave, HE Ignition & Ground "Myth" notes
ECM can be "dead" and still look good.
Bad solder joints anywhere can make engine not start/run but won't set "Codes" because thinks no problems.
Example: L4 TBI driver "transistor" can have problems and not turn on even tho ECM command this to happen and won't set codes.
Related: See my Cave, ECM Heat
Suggest you clean/fix all ground in engine bay and more and coat ends w/ brake or silicon grease.
See my Cave, Wire Service------------------
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
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PatrickTRoof
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JAN 20, 03:18 PM
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All of my engine bay grounds are good, and I've added a couple extra ones too.
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fierobear
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JAN 22, 02:39 PM
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PatrickTRoof
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JAN 22, 11:34 PM
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Mike in Sydney
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JAN 23, 06:37 PM
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Have you checked the clutch interlock switch? It's near the bend in the clutch pedal. I think you can jumper the yellow and purple wires together to by-pass the switch. BE CAREFUL. CAUTION. DANGER, WILL ROBINSON, doing this will let the car start while in gear. [This message has been edited by Mike in Sydney (edited 01-23-2021).]
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Patrick
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JAN 23, 08:05 PM
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In order for the OP not to get confused by various suggestions, I think it's worthwhile to clarify that the engine is turning over but randomly not starting. This rules out safety switches in Park (with autos) or with the clutch pedal (on manuals).
| quote | Originally posted by PatrickTRoof:
Lately my 1985 GT 2.8 has developed a random no-start issue which acts like a bad ICM (no spark or tach signal)... I've even seen it crank for a second with no tach signal, then suddenly catch and fire right up.
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PatrickTRoof
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JAN 24, 07:58 PM
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The clutch safety switch is already bypassed in my car.
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PatrickTRoof
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JAN 26, 03:28 PM
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I've recently replaced the 4 pin connector to the ICM, as well as the grey connector to the coil (white and pink wires). Next I will replace the white and pink wire connector from the coil to the dizzy, because I just checked it and the white wire has cracked insulation, and it is a replacement.
I just received a Matco ICM tester, and decided to try it on a "bad" ICM (no start or tach signal), but it tested good. I'm really scratching my head now.
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olejoedad
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JAN 26, 07:09 PM
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| quote | Originally posted by Mike in Sydney:
Have you checked the clutch interlock switch? It's near the bend in the clutch pedal. I think you can jumper the yellow and purple wires together to by-pass the switch. BE CAREFUL. CAUTION. DANGER, WILL ROBINSON, doing this will let the car start while in gear.
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The clutch safety switch only interrupts the starter solenoid trigger signal.
Everything else would work, but no crank.
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