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What is causing this:

I have a 1992 GMC safari. Twice now this van’ engine has stopped running while moving. Once on the free way going 60mph, and again in a local parking lot. Will not restart. But-- then a couple of days later, starts right up like nothing happened. My mechanic says nothing is wrong. Need to solve this problem as AAA will not tow any more



thank you for your Time…

Spark is failing or fuel delivery is failing. You must first isolate the failure (spark or fuel) then repair the failure. This may mean driving around with the dog-house loose so you can remove it and check for spark and fuel delivery. You can buy an inexpensive “test plug”, a spark plug with an alligator clip attached to it made for checking spark. A can of starting fluid will awaken an engine starving for fuel…Once you know what the failure is, your mechanic can fix it…

Seems problematic, as I just had a complete tune up, all filters replaced and also a new fuel pump replaced. I had it towed back to mechanic, but by the time he looked at it, it started right up. And could not find the problem since at the time there was none. Van did the same thing a couple of days later, had it towed back to apartment and waited. Van sat for a few days, I tried it and it started right up. Now afraid to drive it, as not knowing if it will stop running again or not. 'It’s a bitch when in the middle of intersection and can’t move…

The problem might be with a faulty crankshaft position sensor. This is what sends a signal to the computer for control of the ignition/fuel injection. These sensors are known to drop out causing the engine to shut off, and sometimes when you wait long enough the sensor functions again.

There is a test that measures the resistance of this sensor. But if the sensor isn’t in the failure mode, the resistance will meet spec. However, if you perform this test while applying heat to the sensor with a heat gun, and it’s defective, it will be revealed.

Tester

You may have to do some test driving around the block in order to make the gremlin appear again. Like others have already said, you need to find out if the ignition and fuel systems are working when the trouble occurs. Instead of replacing the fuel pump I would have replaced the fuel pump relay since this trouble acts like a faulty relay problem. Spraying some starter fluid into the intake will make the engine run if the trouble is just with the fuel delivery. If spark is the trouble then even that won’t make the engine run.

I like the idea of using starter fluid. Carry a can with you in the car, and spray it in the intake the next time it craps out. If it fires up, the problem is fuel delivery. If not, you’re losing spark.