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Hoping you guys can point me in the right direction. This started a few weeks back. The car would be running fine, and then at a stop -- it would just die. I noticed that the tach needle would start jumping at idle, and you could feel the engine missing -- right before it would quit running.

Sometimes -- after a lot of cranking it would fire back up. I first changed the fuel filter. No change. I then read about the known wiring harness problem on the fuel pump, so I dropped the tank and replaced the fuel pump and the harness. No change.

Then I changed the MAP sensor, and the TPS. This seemed to help, but within a few days the same thing happened (tach needle starting to jump if I let it return to idle -- and then the engine would die). I found two relays near the firewall on the passenger side inner fender well, and assumed one was the fuel pump relay. They both were marked with the same part number, and so I swapped them -- but no luck. Same thing happens.

So today, I had a buddy spray a bit of starting fluid in the throttle body while I cranked the starter, and it would fire up, and as long as I kept my foot in it -- it would continue running (so-- the new fuel pump is working). But -- as soon as I let it slowly return to the idle speed with the pedal -- the tach needle would start jumping again, and the engine quits. Anything below 1200 rpm.

Any idea's of what to check next? It has not thrown the CEL. Maybe the IAC valve? But it seems more like a fuel delivery problem that is electrical -- with that tach needle jumping. Maybe a intermittent short somewhere?

Last thing. The voltage meter on the dash is almost pegged at 18 volts. I checked it with a hand-held volt meter at the battery with the engine running and I get 16 volts. Just mentioning it as a possible source of the problem.

I'm just scratching my head over the whole thing. :bang:
 

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My 93 would stumble and the needle would jump as I drove around, and when I slowed down. So I bought all new wires, cap rotor and plugs and she runs like a champ. Still getting 20mpg around town with 245K on it.


So what ended up being your problem?
 

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First thing 18 or 16 volts is to high. It will Screw the electrical system.

Un plug the alt and start the car, see if the problem is still there.
Check for a vac leak , hose off , ect.
 

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Way back when I had my '91 Caprice sedan (LO5) and wagon (LO3), I recall having to clean the grounds on the thermostat housing stud. Lots of funny things would happen when these were "dirty".
 
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