No Spark from Coil

Tiny
JGPRO2003
  • MEMBER
  • 1994 CHEVROLET SUBURBAN
  • V8
  • 2WD
  • AUTOMATIC
  • 185,000 MILES
Hello,
Truck sat for over about a year before I started to use it again, I would charge the battery while it sat and started it up every once in a while and would let it idle for about 1/2 hour or so. I planned on using it and it ran fine for about an hour and suddendly died on the street, no warning, nothing just died, some lights on the dash lit up some did not. Towed it home and sat for a couple of days, cranked it and started. Took it for a spin and it just died like before after about 5 minutes of driving. Fuel pump did not turn on, replaced it and truck worked for about and hour and again just turned off. I went to get the pcm codes and noticed no check engine light, checked the pcm in a friends truck (same year and model) and ran just fine. So I have replaced pick up coil, ignition module, main coil and nothing. I don't get a spark at the coil. Power is good to the coil. One thing to mention is I replaced the steering column after it broke down the last time and have adjusted the park/neutral switch at the base of the column. Thanks for your help.
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Thursday, September 17th, 2009 AT 7:58 PM

6 Replies

Tiny
PEAR69
  • MECHANIC
  • 1,482 POSTS
It could be a faulty oil pressure sending unit, or low oil pressure.
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Thursday, September 17th, 2009 AT 11:47 PM
Tiny
JGPRO2003
  • MEMBER
  • 6 POSTS
Would this cause no a no spark condition?
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Friday, September 18th, 2009 AT 1:30 PM
Tiny
PEAR69
  • MECHANIC
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Yes
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Saturday, September 19th, 2009 AT 2:49 AM
Tiny
JGPRO2003
  • MEMBER
  • 6 POSTS
Thank you for your help. I changed out the pressure switch and truck started up after I set the timing. I turned the truck on 4 or 5 times and even moved it around in my driveway. Turned it off while I re-taped some of the wiring harness I had undone earlier, went to turn it off "Dead" again. For the hell of it I told my wife to crank the engine while I pulled on the harness and the darn thing struggled and started. Once it was running I did the same thing and pulled on the harness, sure enough engine choked and eventually turned off. I guess there are some fauly wires somewhere in the harness. I guess I'll check the power and ground wires first.
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Sunday, September 20th, 2009 AT 6:47 PM
Tiny
PEAR69
  • MECHANIC
  • 1,482 POSTS
Make sure the ground (where the negitive cable of the battery connects to the fender/chassy) has a good connection. Trace the ground for the ignition module, back to it's termination point. Make sure it is good.

BTW -- why did you undo the wiring harness?
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Sunday, September 20th, 2009 AT 6:58 PM
Tiny
JGPRO2003
  • MEMBER
  • 6 POSTS
I took apart the harness near the fuel pump relay. I also checked continuity after the fusible disconnects on the firewall. I've been working on this for 3 weeks on and off. At first I was totally taken by suprise when the truck would just completely shut off in a instant. I've had the truck since 1999 and love it. Really want to get it back on the road, again thanks for you help and I will definitely make a contribution, great site!
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Sunday, September 20th, 2009 AT 8:56 PM

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