No spark

Tiny
SHINY SIDES 13
  • MEMBER
  • 1999 CHEVROLET SUBURBAN
  • 7.4L
  • V8
  • 4WD
  • AUTOMATIC
  • 189,000 MILES
Have. 99 suburban 454. Ran great great sometimes wen warm a couple extra cranks to start. Parked it Friday night. Monday morning woul not start. No spark. Has fuel. Have replaced: dist, cap, rotor, plugs and wires, coil, crank sensor and harness, and ignition modal. Still no spark! Have power to coil and modal and harness. Still getting fuel. Why else could it be?
Friday, March 13th, 2015 AT 8:52 PM

11 Replies

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Did you check for proper fuel pressure and injector pulse, engine cranking? I understand, you said no spark, just trying to see if your missing anything else?

Your vcm tells the ignition module what to do on the white ic timing, should be a dc pulse, engine cranking.

Can you check for applicable trouble codes? To check codes yourself, at the least, you need an obd2 code reader. Does the distributor rotor move when you crank it?
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Sunday, March 15th, 2015 AT 2:35 PM
Tiny
ROBERTINMAN
  • MEMBER
  • 5 POSTS
  • 1999 CHEVROLET SUBURBAN
  • V8
  • 4WD
  • AUTOMATIC
  • 110,000 MILES
Hi,

I have no spark at all. I've replaced the coil, ingnition module, crank sensor and cam sensor with no luck.

Previous to this it would run fine as long as you started it every 12 hours or more often. If you went over that time it would start but you would have to crank on it forever finally starting it. I would then run real rough like the timing was off for about 30 minutes and then smooth out and run perfect but if you wait beyond 12 hours you are in trouble.

Thanks for any help you can give I'm out of ideas. Very weird problem, please help
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Monday, May 20th, 2019 AT 1:50 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs, distributor pick-up coil, ignition control module, cam and crank sensors- Note: If it doesn't apply disregard it
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Monday, May 20th, 2019 AT 1:50 PM (Merged)
Tiny
ROBERTINMAN
  • MEMBER
  • 5 POSTS
Will lack of fuel pressure shut down the ignition system on a 350 suburban.
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Monday, May 20th, 2019 AT 1:50 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Will lack of fuel pressure shut down the ignition system. Negative
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Monday, May 20th, 2019 AT 1:50 PM (Merged)
Tiny
ROBERTINMAN
  • MEMBER
  • 5 POSTS
Well.I went in to town and bought a fuel pressure gauge and tested and have no fuel pressure. I thought this might be the case since I'm not hearing the fuel pump at all when I turn the ignition on.

I did test for 12v at the coil and there is a full 12 v at the coil.

I have no spark this is why I asked about them being tied together. Coincidence I don't know, maybe you could shed some light on this.

Should I replace the fuel pump or should I test something else. I tried finding a wire harness at the tank but couldn't find it. Probably on top.

Anyway I appreciate your help

Thanks
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Monday, May 20th, 2019 AT 1:50 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Find the fuel pump connector power the gray wire direct from the battery positive post-did it come On?
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Monday, May 20th, 2019 AT 1:50 PM (Merged)
Tiny
SHINY SIDES 13
  • MEMBER
  • 2 POSTS
  • 1999 CHEVROLET SUBURBAN
  • 7.4L
  • V8
  • 4WD
  • AUTOMATIC
  • 189,000 MILES
Harness to cks good. Harness to coul reading good harness to icm low but reading. Does the bracket for the icm and the coil need to be grounded to intake to fire spark? All I can thjnk of left to check is replace icm harmess, somewhere in wiring in column ignition or PCM. Can't spark to drive to run scan tool live too fat from town!
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Monday, May 20th, 2019 AT 1:50 PM (Merged)
Tiny
ROBERTINMAN
  • MEMBER
  • 5 POSTS
Found the gray wire powered it up from the battery and nothing. Are we talkin bad fuel pump?

Thanks again
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Monday, May 20th, 2019 AT 1:50 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
It shold be bolted to intake but I've seen them run without it. You have to scan to find out what is wrong with engine sensor wise. Check fuel pressure with a gauge as well and check fuses under hood. Also if this has the flat style dist cap they go bad and cause your problem.
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Monday, May 20th, 2019 AT 1:50 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Yes sir-if the ground side is good to go. You're running it direct w/o the fuse, relay and OPSU should come alive
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Monday, May 20th, 2019 AT 1:50 PM (Merged)

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