Random stalling Buick Riviera-getting frustrated

riviera
buick

#1

89 Riviera, 500K+ but has been a good runner.



A couple weeks ago it stalled on me 3 times one day but started right up again. Took it to the shop and cleaned the MAF and Throttle but couldn’t duplicate it. Ran it around town for a week or so and stalled again. Back to the shop and they were stumped but put in a new crank sensor. Took it out this morning and it stalled again. Started right up again.



Fuel pump was replaced 6 months ago and shop says that is fine. We’re just throwing parts at it at this point but I’m considering junking it before I put more money into.



What are the most likely causes for GM cars?



Ignition switch?

Coil/module?

Oil pressure switch?

ECM?


#2

Does it stall at idle? Does it have a idle air controller?


#3

The IAC operates normally and was replaced not too long ago. It mostly does it in straight and level flight under 40 mph in town. No stumble or anything, just like turning the key off.


#4

If none of the warning lights turn on when this happens I would look for a problem with the ignition switch area and the ignition system.


#5

Does only the engine turn off? All the rest of the normal on position stuff works? The engine light and the dash lights are on but the engine is off? If it is really like the key is off then Cougar is right on the money. You really havent given a lot to go on.


#6

Yep, just the engine shuts off. The warning lights and everything else light up.


#7

The warning lights come on but the engine shuts off. That’s what’s baffling. If it was the switch I would have thought everything would go dark.


#8

It’s intermittent, and the ignition could reset immediately. If that’s the case, it’s just like turning the key to “on” and all the lights would work. It’s not like turning off the ignition because of the key position.