GMC Jimmy Backfiring, Not Starting

PUNKUR67

MEMBER
GMC JIMMY

I have a 96 gmc jimmy 4wd with a 4.3. The truck has had a hard time starting every once in a while but ran fine after started. My girlfriend tried to start it the other day and it was backfiring and broke the nose of the starter off. Has new plugs, cap, rotor, fuel filter, and air filter. The distributor has not spun and the rotor spins when the motor is turned over. Seems like a timing chain to me but wanted to make shure before I start tearing it apart. Is there an easy way to check the chain on this motor?

Wednesday, November 29th, 2006 AT 6:24 PM

1 Reply

BACKYARDMECHANIC

MECHANIC
337 POSTS

Sounds like you are right to think its the chain and I don't blame you for wanting to make sure. Since you car has a distributor it's not that hard.
1) remove the # 1 plug from the head.
2) have an assistant turn the key while you place your finger over the plug hole(just tap the key). As you start to feel pressure build up with your finger stop.( You are now on the compression stroke)You now have to turn the motor by hand untill the timing mark on the harmonic balancer lines up with the mark on the block. You should be a top dead center
3) Remove the cap and take notice where the rotor is pointing toward. It should be pointing toward the number 1 tower of the distributor cap. If its way off then the chain has stretched or gears are worn and needs to be replaced. Hope this helps
Backyardmechanic :(

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Tuesday, December 12th, 2006 AT 9:38 AM