Intermittent stalling?

Tiny
BLAZ85
  • MEMBER
  • 1985 CHEVROLET S-10
  • 2.8L
  • V6
  • 2WD
  • MANUAL
  • 330,000 MILES
The vehicle is a semi-restored S-10 Blazer, my daily driver which I have owned for 33 years.

The vehicle will be running perfectly and suddenly misfire a couple of times and stall. It can then be immediately restarted and run perfectly until the next occurrence. The problem has greatly increased in frequency lately. On my last short trip, it occurred 4 times. Now after all these years, I do not trust it.

My first thoughts were it was ignition related. After the first misfire occurrence last fall (but no stall) I replaced the ICM with a new Delphi unit. Also, the entire wiring harness from coil to distributor has been replaced some time ago with all connections firmly soldered and heat-shrink insulated. To see if any poor connections existed and with engine at idle and at operating temperature, I shook and pulled at all the wiring with no change. My next thought was the pick-up coil inside the distributor but my limited experience with them is when they fail, one will get a constant misfire or no start. Have you seen failing pickup coils be intermittent like this? I do not have to turn the ignition off and back on for it to restart, just engage the starter.

Although my first thoughts were ignition, I looked at the fuel supply. The vehicle has a rebuilt VIN R 2.8. Running the 85 carburetor setup Since the VIN R has no provision for a mechanical fuel pump, I am running a Chinese "take" of a Carter P4070 rotary van pump powered of EFE relay which no longer used. Since the pump continues to run during the stall, I kind of ruled out fuel as a cause. I also checked for corroded fuses, grounds and battery connections. None were found.

Any ideas? I am particularly interested in your response concerning the pick-up coil.

Thank you in advance for your response and for the assistance you have provided in the past!
Wednesday, March 6th, 2024 AT 9:19 PM

6 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 43,476 POSTS
Yes, I have seen the pick-up coil fail intermittently. I would pull the distributor and disassemble it to replace the coil. Here is how, check out the images (below). Let us know what you find.
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Thursday, March 7th, 2024 AT 10:12 AM
Tiny
BLAZ85
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  • 45 POSTS
Thanks for your quick response. I will change out the coil and let you know the results. I just wasn't sure about an intermittent failure. I will let you know after I have driven it some. Thanks again, you guys are great!
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Thursday, March 7th, 2024 AT 9:03 PM
Tiny
KEN L
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You are welcome, let me know how it goes.
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Friday, March 8th, 2024 AT 9:23 AM
Tiny
KEN L
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Anything?
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Saturday, May 11th, 2024 AT 12:09 PM
Tiny
BLAZ85
  • MEMBER
  • 45 POSTS
Sorry I haven't gotten back with you sooner but a lot of things have been going on in my life lately and repairing this vehicle was not a priority.
As an update, I changed out the pickup coil but it stalled again within half a block. I kept thinking it was ignition as I could hear the rotary vane fuel pump running. I checked and cleaned every connection, ground, power supply and any other thing related to ignition. Same thing. My next thoughts were maybe the fuel pump was running but not pumping adequate fuel flow. I installed a new Carter P4070 pump but when testing it seemed defective so I warranted it. While installing its replacement, I by chance tried to blow by mouth through the supply line to the tank. I could not so I got my air compressor and blew through it. Hooked up new pump and little if any fuel came out the discharge port, line was clogged up tight again. Long story short, the filter sock in the tank was clogged and would suck together at times causing the intermittent stalls. I dropped tank and changed filter. Been driving it over 3 weeks with no stalls. My preconceived diagnosis it was ignition related was wrong. I should have checked fuel flow earlier. Lesson learned, now if I can just remember it!

Again, thanks for your help. You guys are the greatest!
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Sunday, May 12th, 2024 AT 9:24 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 43,476 POSTS
Glad you could get it fixed, thanks for letting us know. Please use 2CarPros anytime we are here to help.
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Monday, May 13th, 2024 AT 9:56 AM

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