I have spent over a month reading posts trying to fix my 1998 JMC jimmy. First the details: 1998 GMC Jimmy 4x4, 175,000 Miles, Automatic, 4.3 liter. My problem: it won't start-When I crank, it acts like it wants too but it just doesn't. When I first started working on it I had a code for the cam and crank sensors-I replaced them both and it cleared the code but sill would not run right, it would idle great but when driving it would spit and sputter and backfire real bad. I've replaced: plugs, wires, cap & rotor, distributor, spider, cam and crank sensor, ignition module, Coil and PCM. After I replaced the Distributor it quit starting all together. Compression is 120-130 across all cylinders, I have good spark and fuel pressure is 60 PSI to the spider. Timing is right on the money. Battery is pretty good and I keep it on the charger while cranking. I also removed the Cat. it acts the same way with starting fluid. It wants to start but just wont go.

I've had people tell me that I need to take it to the dealer to get the computer reset since I pulled the distributor, crank and cam sensors out. Is this true? If so is there something I can do to reset the system? I've read post about having to do something after you replace the crank or cam sensor but I'm not sure exactly what it is your suppose to do. If somebody could advise me on this I'd appreciate it.

You may wonder why I would offer to pay somebody on a forum instead of taking it to a mechanic. Plain and simple I'm stubborn and don't know what the word quit or throw in the towel means. I want to learn from the experiance and this is more of a hobby for me.

A little about me-I'm fairly competent with vehicles and have fixed my fair share but I'm not a professional mechanic and I'm smart enough to know when I'm getting my but kicked. That being said this is by far the toughest problem I have ever ran into.

 

On my 96 there is 2 timing marks on the crank. If it got worse after the distributor then I would check that. I timed mine wrong a few times after my distributor replacement. Finally got it right, but it sure was a pain. Also, do you have any way to check other sensor inputs? Any code reader that can do that could help a great deal.

 

I actually used the #1 cylinder to check the timing. Everything is right on the money with the timing. I've check it at least 30 times. I have a generic code reader but it doesn't give me the ability to test individual sensors. It just reads codes and as of this post there are no codes in the computer..Any other ideas?

 

The timing procedure on the EDI equiped trucks is more complicated than just putting #1 cylinder to TDC on compression. There are two alignment marks on the crank that have to be properly aligned with their respective references on the front of the engine. The EDI Engine Timing thread details this procedure sufficiently.

Also, the distributor can move in its bore through the lower intake which modifies the CMP retard value. This should be set to zero through monitoring the CMP retard value with a compatible scan tool as you move the distributor in its bore (it isn't a twist, but just movement in the bore due to the bore being larger than the boss on the bottom of the distributor).