1995 GMC C1500 engine cuts out then takes a few minutes to start. Pulling my hair out!

[Hobo]

Any ECU codes? You mentioned none. Check them anyway, regardless of whether the "check engine" light is on.

When it fails to start as you describe, that's your opportunity to identify the problem. While you're along the side of the road have you...

- checked fuel pressure
- checked for spark
- made note of ambient conditions (high / low temps, high humidity, rain, etc.)
- noted any unusual dashboard gauge readings
- used a diagnostic tool, e.g., like DIACOM et al., to see what the ECU has to tell you during the time the engine fails to start


Does it misbehave in any other way at any other time...

- long crank before starting when cold, when hot,...
- failure to start under other conditions than already mentioned
- erratic engine behavior


Is the vehicle history a factor, e.g., comment on...

- rust or corrosion due to sea spray / winter road salt
- major body repairs (can lead to grounding problems)
- major power train repairs (trans swap, engine swap,...)


Sounds like you've replaced plenty of parts. But installing parts doesn't guarantee anything; for example, intermittent low fuel pressure can be due to a poor fuel pump ground and not simply the pump.

 

[Hobo]

my Brother passed away and left me the truck. it was a basket case over the last two years I've fixed just about everything in the truck and in going to gift it to my brothers son who just had a kid and then this **** happens. the truck runs like a top no other issues. I'm buying a 2002 gmc today going to start the whole process of making it new again. I'm going to miss this truck though I really do like it.

 

[Hobo]

I'm going to check the grounds today and do the trouble codes I just looked up YouTube I never even knew there was a diagnostic on this truck

 

[Pinger]

I'd want to check for spark (easy enough to do on the side of the road) the next time it quits. spark/no spark is a diagnostic fork in the road, helping you eliminate a lot of unnecessary work.

Agreed - but can be tricky to do solo.
When I had to do it, I bolted a piece of thickish aluminium under one of the AC compressor bolts and clamped a sparkplug to it with vise grips so that I could see its electrodes while cranking with the key.
Arranging that in advance and carrying a spare plug would speed up the diagnosis.

 

[Jeff Janssen]

Agreed - but can be tricky to do solo.
When I had to do it, I bolted a piece of thickish aluminium under one of the AC compressor bolts and clamped a sparkplug to it with vise grips so that I could see its electrodes while cranking with the key.
Arranging that in advance and carrying a spare plug would speed up the diagnosis.

Or if you happen to have a smart phone you can set up your test plug and take a video of what you see. That seems only a little less work than riding around with a friend all the time.

 

[Schurkey]

Spark tester, not spare spark plug.
www.amazon.com/dp/B003WZXAWK/?coliid=I3S98D7T1J0RLJ&colid=2VLYZKC3HBBDO&psc=1&ref_=lv_ov_lig_dp_it

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Yes, face it towards the driver, or where you can see it standing outside the driver's door. I am usually reaching in through the window to turn the key to crank the engine.

Post #2 is fabulous.

 

[Hpilot]

Mine did the same thing, coolant temperature sensor was bad. Also found the module in the distributor was going bad, heat sink paste was almost all dried up and it would shut down the spark. New distributor solved that.

 

[1998_K1500_Sub]

Also found the module in the distributor was going bad, heat sink paste was almost all dried up and it would shut down the spark. New distributor solved that.

I had the same problem on a 1986 Old Calais 2.5L 4cyl. One summer, it began to act-up "crank-no-start", when parked after running (ambient temps in the 90s) and then sitting for about 10min. But after a sufficient time to cool-down (maybe an hour), it would start and run again w/o issue. I traced it down to "no spark" (that was easy) and finally to the ignition module in the distributor (that took me more time to identify). Evidently it was heat-soak issue.

I replaced the module and thermal paste, and all was good. Maybe replacing only the thermal paste would have fixed the problem, I'll never know.

This could be the OP's problem... or not.

 

[Teddygraham]

I have had your concern before on several vehicles. One had a bad coil, as it got hot it would cause an open circuit and not work. I have also had ignition control modules do the same thing.. get hot and fail.

If you replace the icm, make sure to add some dielectric grease to the base.. to insure good heat transfer to the heat sink

 

[Frank Enstein]

The heat sink compound is a goldilocks deal. Not too much (found that out the hard way), not too little. Just Right.

All it does is transfer heat from the module to the distributor body.

The magnetic pickup may also short/go open with heat as well. That would be a check after you find a no-spark condition.

Grounds, Grounds, Grounds! If you open the hood and can't find the engine, you have a couple too many!

Clean all the plug in connectors with contact cleaner and protectant. I like the DeOxit brand. Mark each connection with a paint pen. Then check "Bad Connection" off your list.

Keep at it. It is very likely to be something simple.

Keep notes.
I know when I get frustrated I get confused. Not sure which one comes first.