96 4.3 randomly dies
 

I posted this in another forum and I don't think its getting much traffic, so I'm reposting here. I'm trying to track down an intermittent problem. I've got a 96 S10 with 81,000 miles and the 4.3 engine. It will die while driving sometimes. Sometimes it takes 10 minutes and it will restart. Sometimes, it will restart right away.

Interesting things to note are the following: (1) The key cylinder was bad and resulted in a lot of flipping the switch back and forth and probably banging on the area (I haven't had the truck very long); (2) I noticed that the tach does not register while cranking (3) fuel pressure bleeds off slowly -- like a pound a minute; (3) Rotor is worn, but not worn out or broken; I've cleaned the contact points in the distributor cap as well (4) tack reads about 200 rpms low and periodically will drop while at a constant speed with no affect on motor or driving feel; (5) about 5 minutes after the car died and restarted last night, the abs and brake light came on for about two seconds and went off again;(6) no CEL codes present.I have not been able to check for spark and fuel after it dies. I was ready for it last night, but it stared right back up on the first crank.

Unfortunately, a lot of these issue seem to be commonplace and all could be unrelated. I've replaced the ICM as the most likely electrical suspect, but now I'm thinking it is an intermittent in the ignition switch. The fact that it just dies and then comes back to life makes me believe its electrical. Also, the fact that the rpms do not register while cranking (and the car will start no problem) is making me wonder about the switch since it feeds the tach and would could be the cause of the abrupt dying of the vehicle. The fuel pump always can be heard when turning the key on and when I've checked fuel pressure, its always been above 55 psi. So while the fuel pump is on the long term to do list, i'm thinking its not the cause for the dying.

Any thoughts, ideas or suggestions? Does your tach register while cranking, but before the engine starts?

Air, fuel, spark.

You need to catch the problem while its happening. Have a spark tester and fuel gauge ready. When it dies see if you have 1" of blue spark and 55 lbs of fuel pressure while cranking. If you travel alone then you'll need a remote start cable. You can tape a fuel gauge to the windshield also.

The ignition switch can certainly be it but there would be a lot more dead at that time.

George