PontiacBonnevilleClub.com

it shuts off while driving, it gives no warning.it sometimes goes days without starting and other times it goes days without shutting as well. the fuel filter good. when it stalls sometimes you have to wait a few hours before it will crank. any ideas of what the problem is would be much appreciated

Is the stalling related to any particular driving situation? If it's on curves (usually right hand), it's likely related to the fuel strainer on the fuel pump or the fuel tank baffles. If it's at any random time, I'd suspect a fuel pressure issue or the crankshaft position sensor. Or possible loose/corroded battery connenctions.

This time of year (more moisture) the battery cables are a prime suspect. Disconnect both cables and pull the protective rubber boots off (you must pull them to find the problem).

Tell us what you find in there......

Im new to the forum and forgive me if theres no such thing on your year car as Im searching for a 1994 but I have been researching similar problems dealing with Pontiacs for quite some time and from what I understand thus far (in accordance with the above two replies) is that there is a main ground bus near the drivers side kick panel--just in front of the A-pillar--under the plastic door sill that controls an array of vehicle functions such as door locks, windows and fuel pump. It seems to me that this is a very common place for such a problem to arise! It is a spot that sees alot of moisture that may complicate/accelerate oxidation of the ground mating.

As well as checking the battery cables and other easy diagnostics, I would check this ground point as well as any other reasonably accessible grounds in the vehicle. If this grounding point is questionable, it appears that permanently soldering the wires at this junction has resolved many peoples problems atleast on this forum. If this copper bar is serviceable, lightly sand it with 200 or similar grit sandpaper and seal the junction with an RTV or liquid rubber (plastidip type stuff maybe). If all fails, and the following idea is confirmed safe to following posters as Ive never tried it and you have a nearby exhaust manifold, I would try renting or buying a fuel pressure gauge, attach it to the fuel rail (you may decide to lightly teflon this connection for added safety), feed it under the hood, tape it to the windshield where viewable, and take it around the block a few times and see if the pressure drops before the engine stalls. This may indicate a bad ground (or low on fuel).

Here is some pictures that Ive run across while searching this kind of problem:
First two of a 1994 Olds 88

We had a Techinfo article on that ground bus issue on the old Forum, and haven't re-posted it yet.

Here's a link to the Gearhead Photobucket folder with our pics:
http://s26.photobucket.com/albums/c120/ ... Connector/


However, the Ground Bus issue generally isn't a common factor in a 'shutdown' scenario. The battery cables themselves corrode inside their insulation. The only way to see it is to remove the rubber boots from the cable ends:


This picture represents what you MIGHT see, but if they look clean, you MUST remove the boot and inspect further. This time of year, moisture causes this problem to be much more obvious. This is perhaps the most common cause of random WINTER shutdowns.

the bat. cables are clean and we have a new bat. the car gives no warning when it shuts off sometimes it will shut off and start right back going 50 mph i don't think that would be a fuel problem. would love to know if anyone still thinks it is. there is no certain driving condition when it happens most of the time while going 45-65 mph, but we do live in the country away from town. how do you check the crank shaft censor? thanks for everyones help you are saving some headaches

Did you actually REMOVE the boots from the end of the battery cables? You MUST do this to see the corrosion. Simply inspecting what you can see won't do you any good until you pull those boots. Your symptoms are classic.

You should ALSO check the ground busses for corrosion on both sides of the car as illustrated above.

You can pull codes yourself. Put an unbent paper clip into the A and B terminals of the OBD connector under the steeringwheel and turn the key to ON. The SES light will flash once, then twice. That means 12 and that it is communicating with you. It will then flash for any codes the PCM has stored.

Example: flash pause flash flash pause flash flash flash pause flash flash flash flash

That means a code 34 is present. It will flash the 34 twice, then the 12 again to signifiy the end of the stored codes, and it will start all over again.

Code definitions for your car are here for the most part:

http://www.pontiacbonnevilleclub.com/fo ... =51&t=1625

A crank sensor will likely give you a 18 or 19 that aren't in the list.

Note, it will flash 12 THREE times, then each code three times, then 12 again three times to indicate the end of the sequence.

12 is actually a viable code which means the DLC port is in communication with the PCM. This will only work for 87-93 cars on this Forum.

My bad. It's been a while since I got a scantool and haven't needed to do the paperclip trick.

J Wikoff wrote:My bad.

Bailiff, whack his pee-pee!

when it shuts off it still has battery power radio, windows, etc. and will spin over but not crank, and other times it does crank. i will try all thats been suggested in the next week or so(have got to work) i am so grateful for all the help. please keep it coming.

thank you so much for your knowlegde

944-LT1 wrote:Im new to the forum and forgive me if theres no such thing on your year car as Im searching for a 1994 but I have been researching similar problems dealing with Pontiacs for quite some time and from what I understand thus far (in accordance with the above two replies) is that there is a main ground bus near the drivers side kick panel--just in front of the A-pillar--under the plastic door sill that controls an array of vehicle functions such as door locks, windows and fuel pump. It seems to me that this is a very common place for such a problem to arise! It is a spot that sees alot of moisture that may complicate/accelerate oxidation of the ground mating.

As well as checking the battery cables and other easy diagnostics, I would check this ground point as well as any other reasonably accessible grounds in the vehicle. If this grounding point is questionable, it appears that permanently soldering the wires at this junction has resolved many peoples problems atleast on this forum. If this copper bar is serviceable, lightly sand it with 200 or similar grit sandpaper and seal the junction with an RTV or liquid rubber (plastidip type stuff maybe). If all fails, and the following idea is confirmed safe to following posters as Ive never tried it and you have a nearby exhaust manifold, I would try renting or buying a fuel pressure gauge, attach it to the fuel rail (you may decide to lightly teflon this connection for added safety), feed it under the hood, tape it to the windshield where viewable, and take it around the block a few times and see if the pressure drops before the engine stalls. This may indicate a bad ground (or low on fuel).

Here is some pictures that Ive run across while searching this kind of problem:
First two of a 1994 Olds 88

I went through a similar situation.

Ended up changing:

Cam Shaft sensor
ECM
ICM
Spark Plugs
Fuel Pressure Regulator

....with no luck.


Nothing help until I changed the fuel pump and the crank sensor.


Your mileage may very, but I had the exact same symptoms.

not as common on your year, but my random stalling (would start right back up in neutral) was caused by a faulty PCM (94/95s are known for their flaky PCMs)

Then, there's me, the poster child for loose connector pins, especially at the PCM, coming from the ICM. Loose/wallowed female pins on the harness side. I don't mention it much because it scares people off. I chased it for months, replaced all kinds of parts for that and another problem. It ate my lunch, but finally discovered it when the car was idling away in Park and I bumped one of the harnesses going into the PCM, causing the engine to die. It was very repeatable after that, allowing me to zero in on the culprit female pin. If you run out of obvious things to try, holler. I don't want to bore these folks with the gory, drawn out details if I don't have to.

From what I am understanding, I would suspect the Crankshaft Positioning Sensor. Back when it went out on our '90, it would do that same exact thing. Most of the time it would not start back up after it was warmed, but as it got worse, it affected driving too. It also never set any codes. I would scan the codes as described previously. If you get anything that would prevent start up, then pursue that, but if you get no codes that would prevent starting, I would pursue this then.

To clarify, the engine just dies correct? The dash, radio, etc react as if the engine just died, and don't actually go out right? If so, then even more so would I suspect the CPS.

we put a crankshaft sensor on and now it acts like the timing is off

Did you unhook the battery for a while to let the PCM reset? Are you sure the sensor was aligned so the balancer rings didn't hit it?