1994 Buick Regal 94 Regal stalling after 15 minutes

LH_MARK

MEMBER
1994 BUICK REGAL
6 CYL
FWD
AUTOMATIC
136,000 MILES

I have been dealing with this issue for the past few months and have taken it to two different mechanics without any resolution.

The ignition coils, spark plugs, ignition control module, fuel filter and fuel pump have been replaced without fixing the problem.

After what seems to be a random issue of stalling, I have been able to narrow it down to a predictable pattern.

After starting the car from a long sit (overnight or after 2 or more hours), it will run for about 15 minutes until it stalls. I have to let it sit for 2 to 5 minutes before its able to turnover.

The correlation of what leads and then follows the stalling: the reading on the oil pressure gauge. Upon first start, the oil pressure is high during idle, above 40 in the 50-60 range. It remains in that range during driving and idle. Then, after the approximate time of 15 minutes, the engine stalls. No stuttering, no chugging, just. Off.

When I finally get it to turn over, the oil pressure gauge reads in the 20 range during idle and a little over 40 during driving. The car does not stall again for the remainder of the drive.

From what I understand, the oil pressure should be higher than usual during first start up but then lowers to normal range after warm up.

Could the stalling issue be tied to the oil pressure switch?

6 Replies

JACOBANDNICKOLAS

MECHANIC
109,709 POSTS

If the pressure went to 0, it may, but if it is holding good pressure, I would say no.

As far as having higher pressure when you first start it, that is a result of the oil being cold and heavier. As it heats up, the oil breaks down and the pressure lowers. This is normal.

Now, what is causing it to die. According to your posting, you need to wait for a short amount of time until it restarts. When it happens, I need you to check for spark and fuel to the engine. One will most likely be missing. I need to know which one it is.

Here are the directions for how to check for them:

https://www.2carpros.com/how_to/how_to_test_an_ignition_system.htm

https://www.2carpros.com/how_to/how_to_check_fuel_pressure.htm

Let me know what you find.

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Friday, November 6th, 2009 AT 11:40 PM

LH_MARK

MEMBER
4 POSTS

Thanks for the tips. However, I'd have to have a mechanic perform those tests. The catch: The times I took the car in, one mechanic couldn't get it to stall and the other mechanic got it to stall once but deteremined it was the fuel pump.

I wanted to reiterate that the ignition coils, ignition control module and spark plugs have been replaced. Stalling continued.

Then the fuel pump and the fuel filter were replaced. Stalling continued.

I just find it interesting that the stalling occurs during the warm up process and after it stalls, it doesn't stall again for the remainder of the drive. Even if the car is parked for 30 minutes and then restarted, it does not stall. It only stalls when the car is parked for an extended period (from about two hours to overnight).

I'm factoring in the oil pressure readings because it's what I notice before and after the stalling.

And to add to this, the car will go through periods of not stalling at all for periods up to two months. How's that for aggravating?

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Saturday, November 7th, 2009 AT 9:55 AM

JACOBANDNICKOLAS

MECHANIC
109,709 POSTS

It sounds like you have the same luck as I do. It does get frustrating. If you want, you could replace the oil sending unit to see if that changes anything. It isn't hard to do and the part is cheap. Should be under 20 dollars.

If you want to try it, let me know and I'll help you.

Joe

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Saturday, November 7th, 2009 AT 10:45 PM

LH_MARK

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4 POSTS

Thanks Joe. I'll check into that as well. I appreciate the help!

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Saturday, November 7th, 2009 AT 10:48 PM

JACOBANDNICKOLAS

MECHANIC
109,709 POSTS

Let me know. Honestly, it isn't too hard to do. However, I really question how it could have this affect, but nuttier things have happened.

Let me know what you find or if you have questions.

Joe

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Saturday, November 7th, 2009 AT 10:50 PM

LH_MARK

MEMBER
4 POSTS

Thanks again Joe.

After giving it some thought and some research, I'm starting to lean in the direction of the fuel pump relay.

After it stalls and I try to start the car immediately, it has the symptoms as if there's a problem with the fuel. I have to wait a bit to start again.

I'm also thinking about the sudden disappearance of stalling for months at a time and then have it return for unknown reasons.

Come to think of it, the stalling first started around this time last year but happened occasionaly and always after the car had been parked for some time and after about 15 to 20 minutes of driving. It stopped stalling until summer arrived then it began stalling (and money being spent on repairs that never fixed the stalling). Then summer ended and the stalling stopped. Then the weather started cooling down even more and the stalling returned.

Temperature fluctuation of the weather along with the normal temperature fluctuation under normal driving conditions? Makes me wonder. It's well worth the money to try replacing the relay. Probably hasn't been replaced since the car was built.

I'll post my results so others can see.

UPDATE: Well, I went out and picked up a new fuel pump relay switch and installed it. I let the car idle from a cold start and it stalled once again at the magical time of appx. 15 minutes, the same time the oil pressure gauge dropped to a normal pressure.

Looks like my next move is to replace the oil pressure switch. What fun!

UPDATE: I finally was able to change the oil pressure switch. It was not a complete waste of effort since the car still stalls one time when it reaches normal operating temperature (around 10-15 minutes). Although I'm still encountering the stalling, my oil pressure guage is now more stable than before and operates like it did in the past. I guess it's just coincedence.

Now to still figure out what's causing the engine to switch off after warm up.

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Sunday, November 8th, 2009 AT 12:38 AM