1988 Oldsmobile Cutlass Supreme Classic Stalls while driving.

Jeromeg78

Not-quite-so-new-guy
Apr 28, 2025
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Hello, all! I recently bought a 1988 Oldsmobile Cutlass Supreme Classic, which I love! I drove it fine the day I got it, but it stalled when I took it out the next day. The car sat for a few hours before I took it back out, and it stalled about every mile or so. Do you have any ideas about what's going on?
 
I had something similar as to what you’re describing happen to my 87 Monte small cap dizzy external coil. Stalled a little over a mile away from home and wouldn’t start. Got a ride home and I grabbed an extra distributor and coil. Was easier to swap out the coil after checking for no spark then the dizzy and that fixed it.
 
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It MAY be an ignition module trying to tell you it's going to give up the ghost. They sometimes give problems first, sometimes they just fail and that's it. Sometimes it's ground issues.

New ignition module. That's what I'd try first based on limited information. Not a terribly tough job, but it's not fun because it's all the way in the back of the engine bay.

If you get one, it's the 7 pin module, and make sure it comes with the little tube of heat sink grease or get some heat sink grease (Don't use di-electric grease) for the mating surfaces where the module sits on the distributor pad.

And we like pictures. Lots of pictures.
 
To give more information on what happens when the car stalls or loses power, as I'm driving maybe about a mile or so, the car will shut off, and three lights will be present: battery, check engine, and seat belt. The car will start after a minute or so, but will shut off once I hit a mile.
 
random thought, does it just act like it ran out of gas? possible you've got something in the gas tank thats getting pulled up onto the pickup blocking it, and then when it quits that just floats away which lets you start it up and get a little ways before it happens again. air, fuel, spark... air's probably not the issue, but nobody's mentioned fuel yet.

the dash lights seems like what you'd expect to see if the car just dies (I think). If its sputtering/kicking/backfiring/etc. yeah I'd start with the ignition. But if it just up and dies repeatedly it might be worth a look.

ofc its almost impossible to diagnose something like this without being there, but we can try.
 
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random thought, does it just act like it ran out of gas? possible you've got something in the gas tank thats getting pulled up onto the pickup blocking it, and then when it quits that just floats away which lets you start it up and get a little ways before it happens again. air, fuel, spark... air's probably not the issue, but nobody's mentioned fuel yet.

the dash lights seems like what you'd expect to see if the car just dies (I think). If its sputtering/kicking/backfiring/etc. yeah I'd start with the ignition. But if it just up and dies repeatedly it might be worth a look.

ofc its almost impossible to diagnose something like this without being there, but we can try.
I can leave the car running in my driveway way and it won't shut off. It will idle all weird but won't shut off, only when driving.
 
It will idle all weird

now we're getting somewhere. like how? rpms fluctuating, missing, stumbilng, too high, too low.... gotta tell us the whole picture
 
Now we're getting somewhere. Like how? RPMs fluctuating, missing, stumbling, too high, too low.... gotta tell us the whole picture
It's being worked on at a shop, so I will let you all know what the findings are. I will be getting the carburetor rebuilt, and the fuel pump. Will have the mechanic look into some more things once he takes care of the work.
 
Not to slight your shop guy because we have no idea of his background, but if he wants to just start swapping carbs, etc., DO NOT LET THEM GET A BOX STORE CARB. If they're rebuilding yours, fine. If they know anything about CCC carbs. But if they're just swapping parts and don't know how to set one up, I fear you're still going to have issues, and they'll bleed your wallet dry by not knowing anything about properly setting up the CCC system and throw a bunch of parts at it and still not get it right.

Another potential issue that comes to mind is the fuel pump. Chances are, it could be original, and when exposed to the ethanol fuels, the diaphragm my be giving out. Any fuel leaks noticed?

You've also got ISC on that carburetor and while I haven't had much experience with that to know what I'm doing in my sleep with that setup, I'm currently of no use for troubleshooting tips. I do know that if it's not working right, it can give you fits.

Also, being that old, it would be wise to check EVERY mile of vacuum hose on that engine for cracks/breaks/mushiness. Trust me. Vacuum leaks are the bane of a good running 307 Olds on a computer. It's free to do, but a PITA either way.

And, if you're going to drive and work on a classic G-body, always get a Chassis Service Manual (CSM).

For $9.90 plus tax to your door. These manuals from Helm when GM still printed them were over $200.

 
Not to slight your shop guy because we have no idea of his background, but if he wants to just start swapping carbs, etc., DO NOT LET THEM GET A BOX STORE CARB. If they're rebuilding yours, fine. If they know anything about CCC carbs. But if they're just swapping parts and don't know how to set one up, I fear you're still going to have issues, and they'll bleed your wallet dry by not knowing anything about properly setting up the CCC system and throw a bunch of parts at it and still not get it right.

Another potential issue that comes to mind is the fuel pump. Chances are, it could be original, and when exposed to the ethanol fuels, the diaphragm my be giving out. Any fuel leaks noticed?

You've also got ISC on that carburetor and while I haven't had much experience with that to know what I'm doing in my sleep with that setup, I'm currently of no use for troubleshooting tips. I do know that if it's not working right, it can give you fits.

Also, being that old, it would be wise to check EVERY mile of vacuum hose on that engine for cracks/breaks/mushiness. Trust me. Vacuum leaks are the bane of a good running 307 Olds on a computer. It's free to do, but a PITA either way.

And, if you're going to drive and work on a classic G-body, always get a Chassis Service Manual (CSM).

For $9.90 plus tax to your door. These manuals from Helm when GM still printed them were over $200.

The shop that has the Olds is familiar with the car, so not worried there. He will be rebuilding the carb and placing a new fuel pump, but the entire engine will be looked at.
 

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