95 Bonneville Stalled, Cranks - No Start

:banghead: 95 Bonneville 3.8 (3800) SE (Non-Supercharged) 204K Mi.

Here's the VIN: 1G2HX52K6S4264365

I've spent several hours the past two days searching this site for the same problem I developed with my Bonnie. I appreciate all the input here and the insight. Now for my little shop of horrors tale.

Purchased the car with 73,000 miles in it in 2004 and up until the the past 30 days had no problems at all. I've got just over 204K miles now and a huge problem. About a month ago I developed this oddball symptom. If the fuel was less than a quarter tank AND I turned Right the car would stall momentarily. Regardless of the amount of accelerator pressing this stallout persisted until the car was righted into the traffic lane. Once done it ran fine. I assumed that the fuel filter was in need of change. Replacing it did not correct the symptom. The symptom continued. I parked the car at work, about 8 blocks from its last Rt. hand turn. This time it sputtered, missed and generally ran rough. When I parked for work was the last time the car has run. I replaced the fuel pump, thinking the strainer or pick-up tube might be having trouble when the gas shifted to one side of the tank on the turns. Turning Left, inclines, downhill, rapid acceleration, nor idle caused the stall, only Rt. Hand turns.

In the beginning I felt this was a fuel delivery issue. A couple of guys from work said the car sounded like it was out of time. Skipping the bloody details here's what I've replaced in addition to the air, oil, fuel filters. The timing chain and gears (yes it was in time and there was no evidence of wear on the sprokets or chain), the cam sprocket inturrupter magnet (that little booger shot across the room and hid...FYI Use great caution when pressing on this little gizmo. Its small, hard to find, and cost $42 at O'Reilly) I also changed the Cam Position Sensor, Crank Position Sensor and fuel pressure regulator. The check engine light hasn't ever come on but I did rent an OBD scanner and the only thing that it showed was "Throtle Position Sensor-Low Voltage" Not knowing exactly what this meant I also purchased and installed a new TPS. Should have read here first and saved a lot of effort on needless parts. Oh well they are installed and have a life expectancy/peace of mind factor.

Initially the car would turn over but would not start. It would "hit" now and then but not start. This I thik is why the advice from my arm chair quarterbacks was the timing being off. I also replaced the Ignition Control Module beneath the coils. Since I had the car on jack stands and the rear plugs were unusually accessable, I changed the plugs and wires. After doing this the car would crank and run by using a steady supply of carb cleaner/starter fluid down the gullett. Still seems a fuel supply problem.

Now this is where it gets strange. Yes, I did read about the ground busses. As a matter of fact, I checked on them today having read up on them last night. I pulled up the carpet on the driver side along the door and did not find the ground bus. I discovered it forward of the door almost under the kick panel. The bus was taped to the outside of flexable protective tubing and was wrapped with about a half a mile of electrical tape. Checking inside, I found the metal strip to be clean, shiney and free of any corrosion. Checking the passenger side yeilded the same. I brushed both with a brass brush and applied dielectric grease, and put them back as i found them, only with less tape wrap.

I have checked for grounds under the hood. Found one behind the battery with three or 4 wires. Two on the drivers side fender one with a single connection containing two wires and one just aft of that with 3 wires. I cleaned all the connections and greased them. I did not find an engine to chassis ground, or a chasis to frame ground. I believe there is another ground at or near the tranny. I'll look for it tomorrow.

I did manage to find and ultimately destroy a few deterrorating vaccuum connections. The "T" that comes off the throtle and supplies the TPS was crumbling. When I moved it to install the TPS it broke. As did the 90 degree fitting on the Fuel Pressue Regulator.

So many parts of this sound like posts from others, its scarey. Have I put in enough information for anyone to take a stab at where things are wrong? If the voltage at the TPS is low, do you know where the ground is for it? What should the voltage be and can it be checked with a voltmeter?

One other semi unrelated queston. Should there be residual pressure on the fuel pressure regulator? When I depress the valve core there seems to be none if the car isn't being cranked. I think the vaccuum bleed off from the bad connections is the culpret there. Just putting out another grass fire in the forrest fire.

Thank you in advance for any help, advice, comments.

I would say you should have residual pressure in the fuel rail for about 15 minutes after the fuel pump stops running. It will bleed off eventually. Might want to check out the fuel pressure regulator. You are doing good by checking grounds and replacing bad vacuum hose. What kind of pressure are you getting at the fuel rail? Should be 41 - 47 psi with the pump running. Do you hear the pump run when you turn the key to the ON position? It should run for a few seconds. Check the fuel pressure and let us know. As for your TPS code, have you verified that all three TPS wires have continuity? After you do that, with the ignition ON, the gray wire should have 5 volts, black wire is a ground, and the blue wire is the signal wire to the computer. Please tell me you have a haynes or chiltons manual, or have an alldatadiy account. It is like working blind without one of those.:frown:

Hey Chem Man,

Thanks for the reply. I was beginning to think mine might be the most unpopular car/issue of all time. Knife in the heart first, no I do not have a Chilton's. I was going to buy one while I was stocking up on unnecessary parts but the auto supply did not stock the book. At that time I was in hopes that I was going to replace a faulty component or two (see the list?) and be done. I did not know I'd be chasing down the individual wires in a harness.

I live alone, of course, which means I don't have a spare set of hands. Here's my plan of the moment. When I can flag down someone to sit behind the wheen and turn the key: I'll be using a #194 light bulb to check fuel injector pulse. I don't have a pressure guage for the schrader valve on the regulator. I do not think there is nearly 47-50 psi on it though. And there is no appreciable residual pressure on the regulator even seconds after having powered up the fuel pump by switching the key to "on". The fuel pump is operational. I hear it and by removing the supply lines from the rail, one at a time, I see that fuel makes it that far.

The engine will start and run momentarily by spraying carb cleaner or starter fluid into the intake. At least I have eliminated a hand full of other possibilities.

Now, should I discover that I'm not getting pulse to the injectors, what would I go hunt down and destroy?

Before you do anything else I would make sure you are getting proper fuel pressure at the fuel rail. Without it, even properly functioning injectors won't be able to deliver fuel. Once you have the correct pressure, and assuming it doesn't fix the problem, then you should check the injector pulse. If you are not getting a pulse, then make sure all the wires to the injector are good. If they are, then its a bad computer(same exact thing happened to me). Otherwise you'll need to repair more wires. If you are getting a pulse, then you'll need to check each injector for clogs.

Good Luck

Okay Chem Man,

Now that I have a line of logic to follow. Just say for the sake of arguement that there is no presure to the rails what causes that how will I correct that issue?

Okay Chem Man,

Now that I have a line of logic to follow. Just say for the sake of arguement that there is no presure to the rails what causes that how will I correct that issue?

clogged fuel filter - you replaced it.
bad fuel pump - you replaced it(I'm assuming that it works properly:) )
clogged fuel line - highly unlikely, I would be shocked if this is the case:eek:
fuel pump doesn't work - checked that it does
broken fuel line - don't have gas under the car/car hasn't caught on fire
fuel pressure regulator is bad

if you don't have pressure at the rail, then I would replace the fuel pressure regulator. Its held on the rail with two torx (I think) screws.

Go out and buy a Chilton or Haynes manual, either it fine. Or go to www.alldatadiy.com and get a subscription for you car. You have no idea how much information you are missing without it.

Wait a minute, before you go off in another direction; let’s go back to your original post where you reported the following:

The check engine light hasn't ever come on but I did rent an OBD scanner and the only thing that it showed was "Throtle Position Sensor-Low Voltage" Not knowing exactly what this meant I also purchased and installed a new TPS.
Now with that said, you need to check the TPS voltage on the grey wire first (with ignition ON). As previously mentioned, it should read 5.0v. Now, check the blue wire for idle voltage (closed TB) and it should read somewhere around 0.5v.

If these readings are correct at the TPS, you need to hook-up a live data capable scanner and take a look at the TPS voltage reading inside the PCM. Irregardless, of the TPS sensor output voltages, this is the reading the PCM is trying to use to control engine functions. If it does not correspond to the voltage readings at the TPS, you have a PCM failure.

Strange as it may seem, this is the exact procedure I used to find a “TPS low voltage” fault in my PCM. Every sensor I checked giving input to the PCM was fine, including the TPS (5.0v in & 0.5 out @ idle position) however, the PCM was either misinterpreting the sensor readings, or making up it’s own parameters. When I looked at the TPS reading on the scanner, it was reading 1.101v @ closed throttle. This was an ACDELCO remanufactured PCM that was only three months old! On this particular car, I replaced the PCM and upgraded the program to a performance version to compensate for a smaller blower pulley. The car now runs perfect and much better performance than with the original PCM!

If you want some info on where to get a PCM, programmed VIN specific to your car, at a fraction of the cost of the dealer, send me a PM.

BTW, I have never seen a "TPS" with a vacuum line going to it! Are you sure this correct? :shakehead

I did manage to find and ultimately destroy a few deterrorating vaccuum connections. The "T" that comes off the throtle and supplies the TPS was crumbling. When I moved it to install the TPS it broke. As did the 90 degree fitting on the Fuel Pressue Regulator.

clogged
broken fuel line - don't have gas under the car/car hasn't caught on fire
fuel pressure regulator is bad
if you don't have pressure at the rail, then I would replace the fuel pressure regulator. Its held on the rail with two torx (I think) screws. From his previous post, (Quote below), I thought he did replace the FPR! :uhoh:
I've replaced in addition to the air, oil, fuel filters. The timing chain and gears (yes it was in time and there was no evidence of wear on the sprokets or chain), the cam sprocket inturrupter magnet (that little booger shot across the room and hid...FYI Use great caution when pressing on this little gizmo. Its small, hard to find, and cost $42 at O'Reilly) I also changed the Cam Position Sensor, Crank Position Sensor and fuel pressure regulator.

Oops, I guess I missed that.:frown:

After many dollars wasted on unnecessary parts and hours spent sweating and swearing the stall issue has been resolved. Thank you all for reading and/or posting suggestions. Here is what the end of this saga looked like.

It was determined that the problem was a fuel delivery issue. I was able to verify the injector pulse, a #194 bullb makes a great test light in that the wires can be bent down and will fit perfectly in the injector electric receptical. Switching the key to the run position several times in a row not only forced fuel into the lines and rails but also created enough force to blow the replacement fuel pressure regulator out of its bowl assembly. Turns out, I replaced the regulator with a wrong one. The replacement part was just enough smaller so that it could slip past the snap ring that holds it in place. Lucky I kept all the old parts pending job completion. I put the old part back, having no indication that is bad to start with. Apparently, the entire fuel delivery problem had to do with leaky vacuum connections. Once the old regulator was re-installed I was able to achieve the necessary pressure. One spray of carb cleaner for good luck and the car reluctantly lumbered back to life.

Now for the new issue: Several times while attempting to get the beast to run it has backfired. I'm supposing that this may have someting to do with what I first sensed as a dead cylinder miss then the ominous cloud of white steamy smoke lingering in the air behind the car. An inspection of the oil dip stick reveals the disheartning milky colored oil coolant mixture I believe caused by a blown head gasket. Please help me affirm this suspision here before I start asking more questions in another thread in a more appropriate topic area. FInal question: Would a leaky or imporperly installed timing chain cover create the same symptoms? These are: dead miss in one cylinder, Coolant in the oil pan, steam/white smoke from the exhaust pipe. The reason I ask is I replaced the timing chain and gears as part of the original issue. I don't know if that gasket is creating the new problem or if I have blown a head gasket by backfire. I'll wait for replies to this then will move the related questoins from here on out to a more suitable topic area.

I cannot thank you all enough for sharing your resources, experience and knowlege. Happy Motoring to you all.

Coolant could be getting into the engine if the front engine cover gasket is leaking. When you replaced the timing chain and reinstalled the cover, you used a new gasket and thoroughly! cleaned the two mating surfaces correct? Someone makes dipsticks that test the engine coolant for the presence of exhaust gases. That would definitely tell you if you have a blown head gasket. The white smoke and dead cylinder appeared after all the work you have done, correct? Did you change the oil after pulling the timing chain?

Remember this engine can also experience failed upper intake manifold egr passages and less common, lower intake gaskets, all coolant issues.

A blown head gasket is highly unlikely here! When an engine “backfires”, it backfires through either the exhaust, or the intake, not the head gasket! The key question we need answered here is what ChemMan asked; did you change the oil after pulling the front cover?

In addition, it appears that you have been using “carb cleaner” on numerous occasions trying to get the engine running. Also, when trying to start the engine (even if you had low fuel pressure) the injectors were firing and dumping fuel in the engine. When the engine finally starts, you would have plenty of raw gas and carb cleaner in the exhaust. When the converter gets hot, it will burn off all the liquid and vapors in the exhaust with a “white cloudy” appearance out the back! How long did you run the engine after it started? I hope not long, or you will need a crank kit next! :uhoh:

Finally, do you still have the “TPS low voltage” fault? If so, you still have a problem there also!

OK just an update on things with the Bonnie. I replaced the upper and lower manifold gaskets both looked like they were in sad shape and leaky anyway. What I didn't fully realize was the failure problem of the entire intake manifold resulting from the hot stove pipe from the EGR valve. Now it appears that coolant is getting sucked into the upper intake manifold by way of this later discovered problem. I believe I can discount the timing chain cover gasket now. If it were bad the oil and coolant could swap spots with each other, or one with the other. But I don't see the coolant getting into the combustion chamber any way but through the intake manifold which is exactly where its pooling up.

I'll put a Dorman OE Solutions UIM on the car and let you all know if that solves this problem. Yes the oil was changed after the timing chain replacement and has been changed twice since then and will have to be changed again. No, the engine was not run for an appreciable amount of time with the coolant getting into the crankcase, I'm hoping to avoid having to re-do the crank, rod and main bearings from the exposure to the coolant.

do you have spark? it sounds like a crankshaft position sensor prob to me.