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I have a 91 cadillac coupe deville had it for 4 years now. So the problem it has now is it turns off while driving really slowly or when on a stop. It does not turn off in the freeway or going high speeds. Now me and my mechanic friend addressed the codes that it had, cam sensor, distributor, neutral safety switch, replaced the cat coverter, did tune up, and it still dies when I am driving it. Now there are no error codes displayed in the computer its all at nothing. So I was wondering what can it be? He said its can be electrical issue, or fuel pump, I am tearing my head on this car and want it to not turn off randomly. Any ideas on what else to check? O and it starts right back up when I put it in park turn it off then crank it again and runs normal.
 

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1992 Fleetwood S&S Hearse, 1993 Buick Roadmaster
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I'd get your fuel pressure checked. I've read several places on this forum about these cars having fuel pumps that slowly weaken, then die. That or a MASSIVE vacuum leak, but I'm sure your mechanic would've noticed a vacuum leak that bad.

It sounds like when you're moving at speed, you're applying fuel pressure at a higher rate, but when you're putting around or sitting idle, the pressure isn't enough and your car chokes out. I severe, ungodly vacuum leak could do something similar, but it just doesn't seem as likely.

Also, there should (I'd imagine, still learning these cars) be a fuel rail pressure regulator. Could be your pump pressure is good but it isn't being regulated up at the fuel rail. I'd suggest taking it to someone with the ability to test the pressure at both places (if this is doable. A mechanic like basscat could definitely tell you more.)
 

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1991 Cadillac Sedan deVille
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Have you cleaned the throttle body and the EGR passages underneath? Clean the throttle body with an old toothbrush and your choice of throttle body cleaner. Also rod out the EGR tubes with a small screwdriver. After you're done, disconnect the battery for a little bit, reconnect and perform idle relearn.

Pull the vacuum hose off the FPR and check for fuel leaking out the FPR nipple. Also, inspect this and other hoses for deterioration.

Check the resistances of your injectors (12-16 Ohms), and listen to them with a stethoscope/screwdriver to your ear. Failing/failed injectors will cause problems at off idle speeds (parking lots) like bucking, surging and stalling. They will also cause a shudder at highway speeds, because the locked up torque converter (VCC) will transmit the engine misfires.
 

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1992 Cadillac Sedan DeVille, 2005 Escalade Ext
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175 Posts
I had this problem when i let my gas tank get to 6 gallons and made hard stops at red lights turn out i had a weak fuel pump.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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Stalling with lower fuel levels when stopping or making turns doesn't indicate a fuel pump issue. Your tank baffles have probably detached.
 

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1985 Sedan DeVille
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Sounds like its conking at idle under load. Most like its related to Min Idle stop screw, Idle Speed controller, or the timing, one of them is probably misadjusted

Try reducing the engine load. IE, turn off the A/C, don't turn the steering wheel, etc
 
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