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Discussion Starter · #1 ·
Hey guys, i have a 1995 lt1 caprice with 120,000 miles i have this problem where the car stalls after driving for like an hour or less when its hot outside and then i wait for 15-20 mins it starts like nothing happend, it happend several times at first it was a vacuum leak but it still happend after i changed the lines last time it stalled i turned the engine on then i sprayed carburetor cleaner it stayed on but when i stopped spraying it shuts off so its a fuel problem im not sure whether its the fuel pump or an electrcal problem or anything else
 

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Welcome to owning old cars. Plan to replace the ignition system, fuel system and transmission. I would start with buying a fuel pressure gauge and checking fuel pressure to confirm your suspicion.
 

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In my limited experience, this is caused by an overheating coil. The two cars I've seen this in, it was caused by (on a 1964 Plymouth Fury I wish I still had) spark plugs I really should've changed a couple thousand miles before, and (on my 1995 RM) a brand-new MSD Optispark.

I never did figger-out what was wrong with that Optispark; the coil it overheated was a <1-year-old Accel HP unit. I was pretty pi$$ed-off at it, considering what it cost; I sent the MSD Optispark back in and it came back refurbished, I never put it back on the car because in the meantime I'd bought an Accel Optispark (for a whole lot less than what the MSD one cost) that worked flawlessly the rest of the time I had the car, and with that same coil so there was nothing wrong with the coil.

In summary, something in your ignition system is giving too much spark or resistance and overheating the coil, which stops it being able to produce a spark until it cools down. Start with the simple things first - when did the car have new plugs, and how good are the plug wires?
 

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Discussion Starter · #4 ·
The spark plugs was changed before 10k miles by the previous owner the wires seem new so i think he changed it with the plugs
But i dont think theres a problem with the ignition system its probably the fuel system cause when it stalled on me i sprayed some carburetor cleaner and it stayed on till i stopped spraying
 

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As Sherlock9c1 noted, try a fuel pressure test. I suggest you run it til it dies, then put a gauge on the fuel rail and turn the ignition back on. Specified pressure on those is 41 psi; if you still have 41ish psi when it won't run, the problem could still be very weak spark. Carb cleaner might be getting enough spark to burn, whereas the gasoline isn't. In either case, a fuel pressure check at the rail when the engine won't run, will tell whether fuel is the problem - and pressure testers are cheap.
 

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When it stalls, does it seem like it stumbles a bit, or just turn off?

When your engine coolant temperature sensor (or harness) goes bad, it can start sending bad temperature values or jumping between the real temperature and say -40 degrees. This can throw your engine back and forth between open and closed loop which can result in a stall.

This only happens once the car is warm enough, so it is (potentially) consistent your description. Very inexpensive fix. Also relatively easy to see if you have an OBD connector and data logging software.
 

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When I first had this problem is was a dirty coil pack assembly. Cleaned it up. Was good to go for months. Eventually the pack needed to be replaced. Good again but then I started infrequently stalling out after short drives. By then there were hesitation issues, etc. The fuel pump was slowly failing. Then the fuel level gave out. Had to change the whole assembly. It's not an easy job for a first timer but I got it done. If that's your problem, make sure the tank is empty when you drop it.
 

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I agree with the others so far. Please test fuel pressure during the failure. Fuel pumps do fail this way. Over 20 years ago, during my college years, my Caprice did this for a few weeks until I had a free weekend to fix it right. My solution was to beat the bottom of the tank with a wooden bat (rubber hammer, large wood block, etc) to get it to restart after it would die. LOL

It could also be ignition related but the symptoms you describe sound fuel related at first glance, so start there. Harbor Freight sells a fuel pressure test kit, just screw it onto the shrader valve (on the back the throttle body).

Unsure what your experience is with FI systems. Be careful... put a towel or larger rag over the area as you screw/unscrew the hose for the gauge. It can spray some gasoline. And you want the spray contained by the towel. As an extra precaution, have a fire extinguisher handy any time you work with fuel. And don't do it in a garage.

On many cars in my lifetime when I've suspected fuel issues, I've attached a gauge and shoved the hose under the hood seal and taped the gauge to the bottom of the windshield... for a long test drive. Then you definitely know.
 
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