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Discussion Starter #1
Hi all, Long time lurker, first time poster.

I have a 1996 regal, 166k. The problem started around 3 years ago with the occasional car not starting, and has gotten worse since then. I only work a mile from home, so it's rare that I experience the problem on my way to work.

What happens is when the car is cold, it will start right up no problem. Usually after it's warm, you can start it up once more, but if you try and start it a 3rd time, it will stall.

Now, it won't stall immediately, but it will chug for around 30 seconds. Once it has completed it's *chug chug* routine, it will not under any circumstances start for around an hour.

During the "no run" mode, there is fuel pressure (as evidenced by taking the cap off the schrader valve and spraying gas all over).

If you try and start it while it's in the no run mode, it will spin over really really fast... kind of like when you have the timing a tooth off on a distributor.

Now, this is what I've replaced: ICM, coils, wires. I've unplugged the TPS, thinking maybe that had something to do with it, but it made no difference.

Normally I would just not worry about it and only drive it back and forth to work. BUT, my daughter is about 6 months away from having her license, and this would be the perfect first ride.

When I was a bit younger, I walked a lot during my first few vehicles for one reason or another... I think it builds character :)


There are 2 dtcs, p0144 (front o2 sensor), and p0300 (random misfire?). I have one of those knockoff elm327 boxes, so if that thing would be of any assistance, it is available.

I just don't know what to do next! I really don't want to just replace parts till I find what was wrong

Any suggestions?
 

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One thing to keep in mind is just because you have fuel pressure at the fuel rail doesn't mean it is the "correct" pressure. You should test it to be sure. I found that out the hard way about 8 months ago.
 

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Check the fuel filter, and fuel pump. When a pump is going out, will work when its cool, but once it warms up it fails.
 

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Hopefully, your problem is fuel related. A fellow engineer on another forum gave excellent advice for 3800's approaching 10 years of age. He believes it is wise to replace the ICM,(which you have done), AND the Crank Position Sensor.(not sure of Cam Sensor failing as easily).
If either fails when you are out on the road, you are dead in the water. Be aware of the fact that electronics like to fail when they are HOT. Typical scenario of CPS iss starting great when cold, getting warm and failing to restart when hot. When starting to go bad, not unusual to hear the scenario about letting the car cool down and able to restart and run for awhile. Even though error codes do not show that type of failure, it may still be something to consider. Just something to be aware of.....good luck KEV

P.S. -does not hurt to try unplugging Mass Air Flow sensor and driving it to check temporarily.
 

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Discussion Starter #6
Ok, so I picked up a gauge and it read 20psi at key-on, and bounced between 22-26psi running.

I also picked up a bosch pump, sock, and delco filter while I was at the parts house with the notion of changing it... 4 hours later, 1 wasp sting, and a skinned elbow, and I have a new pump and filter in.

now it reads 50psi key-on, 55psi running.

Thanks guys for the assistance!

I will post back in a few days if it hasn't croaked on me again, and will definitely attempt to change that CPS if it does.

PS, what kind of job am I looking at to get at the CPS? can you get it out without pulling the crank pulley?
 

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You will have to pull the crank pulley. Other than that its not a bad job.
 

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The cam position sensor could also be the issue but with your low fuel pressure issue fixed you might be in the clear now.

The crank pulley isn't too hard to get off with an impact. You'll just need to take the pass side wheel off and get it from there like changing the oil filter the lazy man way. Most places will also have the proper crank pulley puller for GM's. There is also a dust cover behind the pulley, if you need to remove it to get the sensor out (not sure on your application) be very carefull. I broke one of the tabs off mine removing it and its $70 from the dealer for a new one.
 

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I had the exact same issue with my 94 Buick Regal 3800 motor.

The ICM and sensors (crank and cam) are notorious for having problems after the car warms up.

First, I would recommend you do the crank sensor first, unfortunately you have to remove the crank pulley/damper as stated above, but this may solve your problem. Why? Because, over time, the sensors start failing when they get warm (and start working again when they cool down). At the beginning, it is just now and then, but over time it will get more frequent and eventually you will be stuck for good.

Second, you could change the cam sensor yourself, they are not expensive and they are easy to change with basic hand tools. This may not be your problem now, but eventually the cam sensors can go too. Sometimes, the pickup that is imbedded in the cam gear can get worn/damaged too, but that is pretty rare I am told.

Third, the ICM could eventually be a problem. I had to have mine changed when the car began cutting out. Basically, I am told that the connectors start corroding and eventually cause the unit to fail. Mine failed and left me stranded a few years back. Unfortunately, they are not cheap, but they are easy to swap out (with basic hand tools).

I'm betting that one of the above is your problem (probably the crank sensor), I wish you good luck on the fix.

Regards to all.
 

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Also, keep your throttle body clean inside, buy some cleaner and shoot it at least once a year, if you let it clog up the car will run really rough above idle.

The back plugs are a bear to change I know, but check them every year or two (dependant upon how many miles you drive), if the front plugs look good then the back ones are probably ok too (saving you from pulling any back ones for no reason). Always use anti seize compound on the plugs, whether your heads are steel or aluminum, they will come out nice and easy next time if you do.

Fuel filter change is a good thing too, frequency dependant upon the miles you drive and how old your tank is (is it getting rusty inside, if so it will start clogging the pump and filter). It is a good idea to always fill your tank when you get gas, stops condensation build up which can rust the inside of your tank and clog things up).

Regards to all.
 

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Discussion Starter #11
Just wanted to post a reply and say that the fuel pump was the immediate issue. I haven't had a problem since I changed it.

I forgot to hook the evap line back up to the tank, so hopefully I can get to it without dropping the tank. :)

Thanks again for the help!



The old girl rides again!
 

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Hi there I'm hoping somebody here could help me with the issue I'm having on my 85 Buick Century. It can sometimes be difficult to start when I shut it off and wait a few minutes for the engine temp to climb. And when it does start it generally runs rough until the water pump circulates some cooler coolant and brings the temp back down. I have replaced the following:

Fuel pump
Fuel filter
O2 sensor
Fuel injectors
FPR
Spark plugs
MAF
Ignition coil
Ignition control module

No change. What should I try next?
 

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Lets start at the beginning....... Is the engine running too hot or actually over-heating when this problem occurs?

And, try pulling the small vacumn hose off the fuel pressure regulator to see if it's wet inside that hose and inside the part where the hose fits on? If it is, your fuel regulator is leaking which will cause hard starting especially on a warm/hot engine.......... Jake
 

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Lets start at the beginning....... Is the engine running too hot or actually over-heating when this problem occurs?

And, try pulling the small vacumn hose off the fuel pressure regulator to see if it's wet inside that hose and inside the part where the hose fits on? If it is, your fuel regulator is leaking which will cause hard starting especially on a warm/hot engine.......... Jake
The engine is being turned off when it is at a normal running temperature. I've taken that hose off before, it's dry. And as I mentioned earlier I have replaced the fpr with a new one.
 

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My suggestion at this point would be to get the computer controls scanned with a "diagnostic scanner" to see any codes and more importantly to view "live data" as engine is being cranked over for starting. Also, when you do try to start it, does it have fuel pressure and spark?? Jake
 

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My suggestion at this point would be to get the computer controls scanned with a "diagnostic scanner" to see any codes and more importantly to view "live data" as engine is being cranked over for starting. Also, when you do try to start it, does it have fuel pressure and spark?? Jake
You realize this is an 85 right? It is OBD 1.5 at best, how am I going to read live data from it? What live data am I going to be looking for? It doesn't have problems starting so yes it has fuel pressure and spark. But it runs rough, so it is a mixture problem, or a spark problem, or a fuel problem. The injectors and pump are new however.
 

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A 1985 is an OBD1. And yes, they have lots of data to see....almost as much as OBD2. You mentioned when it started it an rough. If it seems to smooth out after a short while, you could have an injector not holding and dripping into one or more cyls causing a rich condition until it clears. If I was working on it, I would most definitly scan it to see that all sensors are in normal ranges and go from there. You can also see cylinder miss-fire per cylinder etc. This is normally done in an attempt to not have to test every different component. I would also want to put it on a scope to see spark KV. Those early 3800's were somewhat noted to develop weak coil packs....especially the 3 in 1 magnavox versions. It looks like you have already put a lot of parts in so finding the root cause could save you money and time. Getting back to that rough running when you start it......have you monitored the fuel pressure after it has been shut off to see if the pressure holds? You could also try unplugging the MAF SENSOR to see if there is any change. As I remember those early MAF sensors did fail a lot more than the newer types used in later years. A failing MAF will cause all sorts of running problems or result in a no start condition. I must appoligize for some of my replies. I picked up this thread after it was on page 2 and didn't see the first page of info. Anyway, get a good scanner on it and scope the ignition for problems. And make sure the fuel pressure holds when engine is shut off.

Catch up more later, Jake
 

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A 1985 is an OBD1. And yes, they have lots of data to see....almost as much as OBD2. You mentioned when it started it an rough. If it seems to smooth out after a short while, you could have an injector not holding and dripping into one or more cyls causing a rich condition until it clears. If I was working on it, I would most definitly scan it to see that all sensors are in normal ranges and go from there. You can also see cylinder miss-fire per cylinder etc. This is normally done in an attempt to not have to test every different component. I would also want to put it on a scope to see spark KV. Those early 3800's were somewhat noted to develop weak coil packs....especially the 3 in 1 magnavox versions. It looks like you have already put a lot of parts in so finding the root cause could save you money and time. Getting back to that rough running when you start it......have you monitored the fuel pressure after it has been shut off to see if the pressure holds? You could also try unplugging the MAF SENSOR to see if there is any change. As I remember those early MAF sensors did fail a lot more than the newer types used in later years. A failing MAF will cause all sorts of running problems or result in a no start condition. I must appoligize for some of my replies. I picked up this thread after it was on page 2 and didn't see the first page of info. Anyway, get a good scanner on it and scope the ignition for problems. And make sure the fuel pressure holds when engine is shut off.

Catch up more later, Jake
How do you expect I look at this data? And no sir that is patently false, OBD2 includes cars built today, they have incredibly more data values to observe. There truly aren't many sensors to look at in these cars.

One shop has looked at this car and has used a scanning device for these old cars, and apparently nothing stood out to them because they gave me back the car without an explanation.

"You can also see cylinder miss-fire per cylinder etc" - incorrect, this car is not equipped with knock sensors and uses a cap and rotor.

Injectors: The injectors are new, I replaced all 6, 0 change comparing before and after behavior.

"I would also want to put it on a scope to see spark KV. Those early 3800's were somewhat noted to develop weak coil packs....especially the 3 in 1 magnavox versions." - again, no coil packs, but spark coil has been replaced as well.

"It looks like you have already put a lot of parts in so finding the root cause could save you money and time." - parts are cheap, cheaper than a scope and a obd1 gm scan tool.

"You could also try unplugging the MAF SENSOR to see if there is any change. As I remember those early MAF sensors did fail a lot more than the newer types used in later years. A failing MAF will cause all sorts of running problems or result in a no start condition." - You'll see above I also tried replacing the MAF, but no effect/change"

"And make sure the fuel pressure holds when engine is shut off." - Fuel pressure has been tested as late as 2 hours after engine was shut off, it holds.
 

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One more thing on the fuel pump, when you manually activate it, it should pump 1 pint in 30 seconds or less......proper volumn.... Jake
I can't confirm volume at start, but considering it has no problem running at WOT, I would like to think it has enough volume to idle. I have also noticed an additional, consistent, repeatable symptom that I am sure is related. When I start the engine cold, if I sit there idling, the engine will eventually stall/die about half a minute to a minute after starting, or it has also happened when first putting it into gear reverse or drive. When this happens I start it again, it starts with no problem, and has no problem idling afterwards.
 
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