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#3462 of 3508 Buick 3.8 shuts off after 5 minutes
Apr 04, 2010 (12:45 pm)
Hello everyone, I have a problem with a 1991 Buick regal with the 3.8. The car will start once every few days and run for 5 to 7 minutes then shut off with no sputtering or anything and will not restart for another day or two.
The car has 81k on it and the engine has been replaced with a 91 LeSaber 3.8 with the same approximant mileage. The car ran fine until the little magnet on the camshaft gear fell off. As I did not need the car just then, I left it sit for about 6 Ė 8 months before repairing it. When I replaced the magnet, I also lifted the engine up enough to remove the oil pan so I could repair a dent and replace the leaking pan gasket. Once it was back together, it ran fineÖ. for a while. After about 3 weeks, it started to shut off occasionally while driving. It would restart easily. The problem progressed gradually until about 3 months later when I did not trust it to even leave the yard. I tried to correct the problem as it continued to get worse and worse, now, Iím out of ideas.
I know that the problem seems to be that the injectors are shutting down. When it shuts off and I try to restart it, the plugs are dry even after several minutes of spinning the starter. Sometimes, but not always, when it shuts off the charcoal canister purge valve is clicking like crazy. I also noticed that rarely the vacuum hose from the pressure regulator to the intake manifold block is collapsed. It used to run for a bit if I sprayed it with starting fluid but sputtered and staled out in a short time. I should mention that there are never any error codes when this happens and the check engine light does work. On occasion when it is running and Iím in the car, it seems that if Iím giving it gas, it runs a little longer than if I let it sit and idle but Iím not real sure that this is the case.
So far I have replaced the fuel filter, fuel pump, fuel pressure relay, fuel pressure regulator, computer, charcoal canister purge valve and the mass air flow sensor. Nothing has seemed to make any difference. Iíve checked the gas cap and the vacuum hoses from the purge valve to the tank and there is no blockage. There are no vacuum leaks either.
Iíve been working on cars for nearly 30 years and this has me totally stumped. I may have tried a few other minor things or replaced other minor parts but what I have listed is all I can think of currently. Iím thinking I have an electrical or vacuum problem. Iím also thinking of having a Buick bonfire in the near future. Any help or thoughts on this problem would be greatly appreciated. Iím nearly ready to just get rid of the car and would have by now but it is in excellent shape and I never thought I would have put so much money into it and have the problem just get worse. Thank you.
#3463 of 3508 Re: Buick 3.8 shuts off after 5 minutes [ronbuick91]
Apr 04, 2010 (2:54 pm)
You need to verify if it's electronic. Spark? Injectors?
Crankshaft position sensor would be my thinking. Lots of people have had trouble.
#3464 of 3508 Re: Buick 3.8 shuts off after 5 minutes [imidazol97]
Apr 05, 2010 (10:15 am)
How would I go about this, the car has spark and I doubt all 6 injectors would fail at the exact same time only to work the next day for another 5 minutes. Would the crankshaft sensor fail intermitantly like that? When this all started I has also replaced the control modual under the coil pack thinking it might be faulty and sending some kind of shut down signal to the ECM
#3466 of 3508 Heads rebuilt after Hydro lock
Apr 05, 2010 (6:10 pm)
So I replaced my heads after a hydro lock. Hydro lock happened after engine was shut off. Ended up having to replace my TPS sensor as well... My mistake I installed it wrong. Next I replaced my o2 sensor because I got I think it was an 1133 code. That fixed my stalling after 5 minuts of running problem. Now I am getting a code I haven't read it yet... Anyway when I am on the freeway going around 70 add a little gas it sputter till I get up to crusing speed again. Any ideas. I cannot the engine sounds fairly good. Not black smoke and no eating of fluids although it seems to be running a little hot so I think I may have a lean conditions I have a feeling the code will be o2 again But will post as soon as I find out. Just wanted to get this out there. I am thinking of renting a fuel pressure tester. Let me know your thoughts.
*Added info... Just got the code. P0171 on bank 1 so... My understanding of that is that is on cyl 1 or plug 1? No other codes.. Code just be a plugged injector but that would cause a misfire right? In case you are wondering this is a 96 buick regal 3800 series engine.
#3467 of 3508 Re: Buick 3.8 shuts off after 5 minutes [ronbuick91]
Apr 05, 2010 (7:47 pm)
I didn't see any of the other threads, but your computer is not throwing any codes? Have you done a pressure test on your fuel?
#3468 of 3508 Re: Buick 3.8 shuts off after 5 minutes [erwisneski]
Apr 06, 2010 (2:58 pm)
Correct, computer is not throwing a single code. I had a remanfactured ECM in it and just for kicks I went and pulled another ECM out of a salvage yard, car does the darn thing. After it shut down recently, I pulled the fuel pressure regulator and there was gas in the rail under the regulator. I replaced the regulator with a known good one and the car would still not restart. Its been about 2 days now so I'm thinking of going out and starting it again this time being sure to hold the gas pedal down to maintain a very fast idel. I suspect that if it runs longer than 5 to 7 min without shutting off, it will no doubt die as soon as I release the gas. Will post the results.
#3469 of 3508 Re: Buick 3.8 shuts off after 5 minutes [ronbuick91]
Apr 06, 2010 (4:47 pm)
You've replaced the fuel pump. But I'd rent or borrow at a local Autozone a fuel pressure gauge and install it to watch what happens while the car is running (when it feels like starting or when cranking).
I'd replace the collapsing vacuum line from the fuel pressure regulator.
I'd connect a little light bulb, the little marker bulbs with two wires for contacts, into the injector on one of the cylinders while cranking when it won't start. See if you're getting a good flash with each pulse of the injector.
Related to that is the main computer. I would think about replacing it or switching if you know someone with a running version of your car.
But the clicking after the car shuts off sometimes might be a sign of low battery voltage or a poor connection. Is the battery fully charged? Are connections clean?
Have you taken off a plug wire and put a spark plug on grounded to the engine and looked at the spark while it's cranking?
#3470 of 3508 Re: Buick 3.8 shuts off after 5 minutes [ronbuick91]
Apr 06, 2010 (7:00 pm)
Just curious have you done a fuel pressure test? I am dealing with a lean condition on mine and I have no idea at this point what it might be. I just took my fuel rail out and blew out the injector. Next I am going to do a fuel pressure test. only thing on mine I can think of at this point is fuel pressure regulator.Just curious and I don't work on cars but if I am not mistaken you can by obd which hook into the computers and have advanced diagnostics which can tell you what different things are doing... It may help you to do that. Let me know what it was in the end.
#3471 of 3508 Replaced head gasket now running lean
Apr 06, 2010 (7:09 pm)
I recently lost all my water in the engine. So instead of just replaceing one thing I took it down to the heads. Had the heads milled and a valve job done. I replaced the manifold gasket as well as the entire plenum. I later found out the plenum is a real issue in these vehicles. Anyway it is running but bank 1 is running a lean condition. Any ideas? I am aiming towards injectors but don't want to pay for new one unless I am sure. I blew the injectors out today but unsure if that will really do anything as it is a sealed unit well until voltage is applied. At least it appears to be a sealed unit. Please any suggestions are welcome. One thing on start up it "shutters" and sputters and on the frreeway around 70 when applying gas it bogs down. This is a 96 buick reagle 3.8. Replaced O2 sensors as well as the throttle position sensor. Thanks in advance