Will not start, backfires

Tiny
BILL WILSON4
  • MEMBER
  • 2004 GMC SIERRA
  • 4.3L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 60,000 MILES
I had a misfire code truck would not start just cranks, replaced Cap and rotor, wire's and plugs 1 year ago, l just replaced the coil and ICM. Will not start, backfires, is trying to start.
Monday, December 23rd, 2019 AT 1:55 PM

1 Reply

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon,

I would check the compression first to be sure the timing chain has not jumped time. Backfires are when spark happens at the wrong moment.

https://www.2carpros.com/articles/engine-backfires-while-running

https://www.2carpros.com/articles/how-to-test-engine-compression

Roy
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Monday, December 23rd, 2019 AT 2:46 PM

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