Author Topic: 1990 Buick Regal Custom problem  (Read 6518 times)

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1990 Buick Regal Custom problem
« on: May 01, 2010, 08:22:51 PM »
I recently purchased a 1990 Buick Regal Custom with a 3.1L V6, and I'm experiencing a problem after it's been running for about 10-15 minutes. The car will hiccup and sputter like it's running out of gas, and won't crank up until it's been sitting for about 20-50 minutes. The fuel pump engages whenever I turn the key, but I don't know if it's trash or something else that's causing it to malfunction after it's been running for awhile.

Also, the Schraeder Valve on the FI system consistently has air building up in it, regardless of how much air/fuel releases from it when the engine is off. Is this a problem with the Fuel Regulator? I've also been told it could be the EGR Valve, but if that's case, would it also be the cause of the air in the Fuel Rail?

I'm looking for any help on the situation, as I don't have money to pour into this car on random parts.



Thank you,


Chris Wierts

Linkback: http://forum.trustmymechanic.com/b1/1990-buick-regal-custom-problem/25446/

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Re: 1990 Buick Regal Custom problem
« Reply #1 on: May 02, 2010, 10:47:09 AM »
There's no fuel present in the vacuum line. I let the car idle for about 15 minutes, and then revved the engine to a steady RPM to increase the temperature. Noticed one of the fans isn't running, and the temperature light comes on. It's like the engine cuts itself off when it gets too hot, so what would be my best course of action to diagnose why the fan isn't running?

Thank you,


Chris Wierts

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discretesignals

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Re: 1990 Buick Regal Custom problem
« Reply #2 on: May 02, 2010, 11:31:23 AM »
Air in the fuel rail could mean that you have an empty tank of fuel or the pump is sucking in air somehow.  You could connect a fuel pressure gauge to the fuel rail and check for static pressure when you turn the ignition on when the engine doesn't want to start.  Fuel pressure should be around 40-47 psi.  


When the one fan is running, is the air coming from it hot?  Is the upper radiator hose hot and the lower cold?  What is the coolant level and condition in the radiator?

The primary cooling fan comes on if coolant temperature is greater than 223 degrees F, the a/c is turned on and the vehicle speed is less than 70 mph, and/or if the a/c high side pressure switch opens.

The secondary cooling fan will come on if the ECM is in backup mode, coolant temperature is greater than 227F and the a/c is off, if the a/c is turned on and the vehicle speed is less than 40 mph, or if the a/c pressure switch opens.
« Last Edit: December 31, 1969, 06:00:00 PM by discretesignals »

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Re: 1990 Buick Regal Custom problem
« Reply #3 on: May 02, 2010, 12:28:12 PM »
Primary fan is coming on while the vehicle is parked and idling, so the 223 temperature is being achieved. Of the secondary cooling fan variable conditions, our scenario is the coolant temperature is at or above 227 degrees, and the AC is off. Secondary fan still not engaging, up to the point of when the engine stalls.

-Should the primary fan continue to run after the engine stalls, until the coolant temperature is reduced below 223?

-What's the best way to determine if the secondary fan is good?

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discretesignals

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Re: 1990 Buick Regal Custom problem
« Reply #4 on: May 02, 2010, 12:40:27 PM »
The one way to test the secondary fan is to turn on the a/c with the engine running.

The primary will stay on with the engine off if you have the ignition still on and the engine coolant temperature is at the temperature to enable that fan.  Otherwise is should turn off when you turn the ignition off.

The primary alone should be able to control the engine coolant temperature at idle.  It should cycle on and off.  If it never turns off and your overheating, then you need to check the coolant system.  Is the air coming from the primary fan hot?  Are both radiator hoses hot?  What is the condition and level of the coolant in the radiator?
« Last Edit: December 31, 1969, 06:00:00 PM by discretesignals »

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Re: 1990 Buick Regal Custom problem
« Reply #5 on: May 02, 2010, 01:56:55 PM »
The values below must be confirmed with a FUEL PRESSURE GAUGE. Let's deal with the stalling problem first as it's more pressing than the fan issue. You can borrow a fuel pressure gauge for free at any Auto Zone Store, by taking advantage of their LOANER TOOL SERVICE.

Best Regards
Jane

Ignition key on and engine off fuel psi should be 40.5 – 47 psi

Fuel system pressure at idle should be 30.5 – 44 psi.

Fuel pump pressure psi with the return line briefly restricted should be 47 psi

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Re: 1990 Buick Regal Custom problem
« Reply #6 on: May 02, 2010, 02:00:48 PM »
I took the non functioning fan off and tested it by hooking it directly to the battery, and discovered it's dead. Did the same to the working fan to make sure that my fan - battery wires were functioning, and the fan spun.

Jane:

Is it possible the engine is cutting itself off due to it overheating? As I said, it doesn't seem to want to start, or stall until it gets cooled down or over heats.

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discretesignals

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Re: 1990 Buick Regal Custom problem
« Reply #7 on: May 02, 2010, 02:11:02 PM »
There is no safety/protection method that disables the engine in the event of it overheating.  

You may have three problems.  One, the engine is stalling and not restarted until whatever is causing it cools off.  
Two, you have a secondary cooling fan out, but that shouldn't cause the engine to overheat unless it is really hot outside and the a/c is running. Three, something else is causing the engine to overheat.

Does it overheat while you are driving at highway speeds?  Is the air coming from the primary fan hot?  When are you going to answer those questions? Laughing

Both problems with it overheating and stalling are important, but I believe the overheating should be figured out first, if the stalling/no restart problem is intermittent.  Overheating will destroy the engine.  Stalling/no start won't damage the engine.

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Re: 1990 Buick Regal Custom problem
« Reply #8 on: May 02, 2010, 02:45:22 PM »
Quote
Does it overheat while you are driving at highway speeds? Is the air coming from the primary fan hot? When are you going to answer those questions?


Haha, sorry. Laughing  Yes, the overheating dash indicator comes on at highway speeds. Also, I live in Georgia, so it's quite hot during the summer. And I'm currently unable to tell you if the air coming from the primary fan is hot because the coolant container is currently removed until I can replace the secondary fan motor on Tuesday.

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Re: 1990 Buick Regal Custom problem
« Reply #9 on: May 02, 2010, 03:04:45 PM »
I took the non functioning fan off and tested it by hooking it directly to the battery, and discovered it's dead. Did the same to the working fan to make sure that my fan - battery wires were functioning, and the fan spun.

Let’s not complicate something that is so simple and obvious. Based on the above you now have to make a trip to a junk yard and get another fan.

Install the fan, run the engine and let us know if that resolves the temperature issue. DO NOT DRIVE OR RUN THE ENGINE TILL IT OVERHEATS. At the first sign of the temperature going higher than normal shut the engine down, open the hood and do nothing till the engine COMPLETELY cools down.

At that point let us know the results and we will instruct you further. Based on past experience I’m thinking a failing CHECK VALVE at the fuel pump. If that’s the case the fuel pump will have to be changed.

Post back the results of the fuel pressure psi checks at your earliest convenience. I didn’t bother to read ALL of your past postings. Can you please tell me if the fuel filter has been changed recently? Checking the sock screen > filter AT THE FUEL pump would be a good thing. Note that this is a SEPARATE and COMPLETELY different filter from the standard fuel filter that routinely gets changed. If it looks clogged or collapsed change it.

Stay in touch with us and keep us updated. While the stalling issue appears to be fuel related it could also be ignition > spark related. We are here to help you and address that issue as well, but not too much to soon. It's better if we address your issues in stages and by taking baby steps.    

Best Regards
Jane

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Re: 1990 Buick Regal Custom problem
« Reply #10 on: May 03, 2010, 11:48:46 AM »
I'll be getting the Fuel Pressure Gauge and fan motor tomorrow, I'll post an update when I replace the fan motor/check the pressure.

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Re: 1990 Buick Regal Custom problem
« Reply #11 on: May 03, 2010, 05:34:31 PM »
Did a bit of sleuthing today, and noticed that when the condition occurs, there's no spark being supplied from the plug wires. The previous owner replaced the ICM and one of the coils. What could be causing the lack of a spark? I want to say that it isn't a fuel problem as I previously thought, is there any way to test the ECC/ECM?

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discretesignals

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Re: 1990 Buick Regal Custom problem
« Reply #12 on: May 04, 2010, 04:48:55 PM »
ECM won't cause a no spark on that one.  Jumper A to B in the diagnostic connector under the dash and see if there are any trouble codes being stored.  The check engine light will flash the codes.


The ignition control module will fire the coils as long as it is getting a crank signal and has power and ground.  Even if the ECM is dead the ignition module will fire the coils.  The only reason an ECM wouldn't cause the ignition module to fire the coils is if the ECM is keeping the EST bypass closed and not controlling the timing (very very rare).  The ignition module will be in base timing mode when cranking the vehicle, so the module is controlling spark.  Check for power and ground to the ignition control module with the ignition on.  Then check for a crank sensor signal from the crank sensor.  The crank sensor should generate an AC voltage as you crank the engine.

If you have a crank signal, power, and ground to the module, the module is faulty.  If you don't know how to check these things, you need to take it to someone or find someone that does know.

 

You also need to figure out the overheating problem, before you burn the engine up, unless that has already happened.  The coolant fans aren't the cause of the engine overheating if the engine if overheating at highway speeds.  You need to look at things like stuck closed thermostat, internally clogged radiator, blown head gasket allowing combustion gases into the coolant system, etc.


« Last Edit: December 31, 1969, 06:00:00 PM by discretesignals »

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