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1995 Grand Prix, will not start.....


rklipscomb
08-02-2010, 06:14 PM
The car is a 1995 Grand Prix with a 3100 engine.

I have been working on this issue for about a week now. I will start at the beginning.

I read in the forums about an issue with the "O" ring failing on the unused distributor opening on the engine, causing an oil leak on the top of the engine. Well I figured that would be an easy one to fix, until I tried it.
The first thing I did was to cover the fuse boxes and the computer in the engine compartment with plastic, to avoid any major water getting into these. Next I decreased the engine, then with my pressure washer set to low pressure, I cleaned the engine. After waiting about 1 hour after the cleaning. I started the car and drove it to the front where the garage was. It died before I could get it into the garage. Thinking it could just be a little wet, I pushed it into the garage and started the procedure to fix then "O" ring problem. It took a while figuring it out but I think I did just fine.

I put it all back together knowing I had fixed that problem.http://www.grandprixforums.net/images/smilies/th_laugh-lol2.gif When I tried to start he car it would turn over, but not fire. So I checked for spark at the plugs, which I had, so I moved on to fuel.

To check the fuel, I installed a gauge on the fuel rail, reading 42psi, which is good for this engine. Just for good measures I replaced the fuel filter. I tried to start again, nothing. Well I gave it a small shot of starting fluid to check to see if it would try to start, and it does. But then dies. I checked for voltage at the injectors on the red wire, of which I have 12 volts. Do they switch the ground on the injector to pulse fuel into the block?

Thinking about the problem, I have fuel, I have spark, but I didn't think that I was getting the signal to fire the injectors. So I started investigating problems for that. I ended up replacing the cam position sensor, thinking this is the timing mechanism for the engine. Well that did not change anything, it still turns over, but will not fire. Again I gave it a shot of starting fluid and it tried to fire. I have checked all the fuses in all 3 fuse panels, all are good.

I went through most of the electrical connections, reseating them and adding a little DI-electric grease to the terminals. Nothing changed.

Now I am wondering about the passcode theft deterrent system the car has. It has a key with the resistor built into the key. I thought maybe I somehow changed the resistance in the system. I tried the, turn on the key for 10 minutes, turn off, and then retry to start. Still having the same results. http://www.grandprixforums.net/images/smilies/th_nervous.gifhttp://www.grandprixforums.net/images/smilies/confused.gif

At this point I am at a complete loss as to where to start the next phase of the troubleshooting process. I do not have access to any of the technical manuals GM mechanics have for troubleshooting purposes. Any one have an idea where to go from here.http://www.grandprixforums.net/images/smilies/smile.gifhttp://www.grandprixforums.net/images/smilies/th_winking.gif

tblake
08-03-2010, 07:40 PM
To answer your question, yes the injectors are triggered by the negative ground wire.

Is your security light on or flashing?

Might want to try a spair key for arguements sake.

Also might not be a bad idea to disconnect the battery, remove the pcm, and clean the PCM connectors and terminals.

richtazz
08-04-2010, 09:51 AM
Your issue is definitely fuel related, as it fires on the starting fluid. The PCM is mounted under the hood in the passenger side fender well area behind the headlamp. I agree with Tim (Tblake) that you need to inspect the wiring to the PCM as well as the PCM itself. Also double check the large wiring harness connector near the alternator, as this harness includes the fuel injector wiring. You can also check for injector pulse by unplugging one of the injectors that you can access without removing the upper plenum ( I believe cyl #5, the front bank, drivers side is one of them) and either inserting a noid light ( I believe A-Zone and Advance offer a noid light kit in their free tool loan program) or by taking a small automotive peanut bulb (part #194) and straightening the wire leads out and inserting it into the injector plug. If the light flashes, then you have injector pulse, if it doesn't you found your problem.

rklipscomb
08-04-2010, 10:48 AM
Security system, I checked out. I unplugged the connector going to the steering column and the security light came on the dash solid. when I plugged it back in the security light went back out, so I believe that is all working correctly. It will flash when you first turn on the key, but I believe this is part of the default setup for this car.

I have already checked out the PCM connections, at the very beginning of this problem. I don't think the problem is in the connections, but it could be in the PCM itself.

I also went through every connections I could find, checked for water and put DI_Electric grease in the connections. I paid close attention to the connections going through the fire wall.

Going to inspect the bottom of the motor today looking for any problems there, wish me luck.

I found the wiring connection today that goes to the injectors themselves. Pulled it apart and put a 12 volt pin light in line and then cranked the engine over. I did not get anything voltage wise, so the problem has to be in what ever gives the signal to the injectors to fire. Trying to locate a noid light to investigate farther.

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