Jump to content

3.1 won't start replaced everything except ECM


red92s

Recommended Posts

Tried searching for a similar situation to this but didn't come up with anything.

 

Anyway my car decided not to start one day. Starter works well, Fuel is getting to injectors. Prior to this I had a code 42, so I replaced the ignition module which cleared up that problem. However now the car does not start at all and has no spark. Crank position sensor didn't help.

 

I'm thinking the ECM has either had it or maybe there is a resistance problem in the injectors. No blown fuses or bad connectors anywhere and no codes.

 

Any help would be greatly appreciated.

Link to comment
Share on other sites

Tried searching for a similar situation to this but didn't come up with anything.

 

Anyway my car decided not to start one day. Starter works well, Fuel is getting to injectors. Prior to this I had a code 42, so I replaced the ignition module which cleared up that problem. However now the car does not start at all and has no spark. Crank position sensor didn't help.

 

I'm thinking the ECM has either had it or maybe there is a resistance problem in the injectors. No blown fuses or bad connectors anywhere and no codes.

 

Any help would be greatly appreciated.

 

 

Does it at least crank?

Link to comment
Share on other sites

  • 2 months later...

Car has now died again..... I am getting really annoyed at this thing and if it didn't have a 5 speed I would give up on it...

 

Anyway if you don't get a code 12 when you check the data port under the dash is it safe to assume that the ECM isn't working properly?

 

I had replaced the ECM at one point and everything was going great and the car just died one day and never started again. everything else in the ignition system is brand new and is still good as far as I can tell.

 

any thoughts? Could my new ECM have died in the space of a month, is there some problem that fires these things...

Link to comment
Share on other sites

I had a problem with mine. I thought it was the starter. I replaced my started in Part Source's Parking lot one day. Swapped it and nothing. Was ready to give up and took another look and started removing my air box. Found a ground wire melted to exhaust manifold. Cut the wire, butt connector and it worked like a charm.

Link to comment
Share on other sites

Since you have a no-start condition and no code 12, you might have another ECM failure on your hands.

 

Here's a troubleshooting chart for a "no code 12" to help you determine what exactly is bad. It's from a 1990 factory manual, but should be the same as your 92.

 

http://i44.photobucket.com/albums/f14/platjblser/IMG_4200.jpg

http://i44.photobucket.com/albums/f14/platjblser/IMG_4202.jpg

Link to comment
Share on other sites

Replaced ECM with remaned one (again) no fix. Looks like the problem is in the injectors. But Does anyone know what changes there were between 1990 and 1992 in the way the ECM and Fuel injectors interface. I have a 1990 manual but none of the wires colors in the fuel injector driver circuit match up.

 

Since all ignition components are new this has to be it. Also I get fuel into the rails but none of the injectors will light up a Blue Point test light like they are supposed to.

 

Thank you very much for the help so far.

 

This one just won't go away....

Link to comment
Share on other sites

Could be a intermittent short in one of the injectors. Seeing as its a mpfi batch fire car, when one injector shorts, they are all effectively shorted out together.

 

I would try 6 known good injectors and inspect the injector wiring harness.

 

Link to comment
Share on other sites

I have a 1990 shop manual and the car is a '92 they definitely changed some wiring in the interim. I was wondering if anyone out there has a 92 shop manual and could find this diagram. (under driveibility and emissions) so I could see what pins go to where, etc.

 

schematic004.jpg

Link to comment
Share on other sites

Thank you very much GOT2B GM, those are indeed pretty different between those years, hard to believe they would do that with how common the 3.1 was across the whole GM range....

 

This should work pretty well, now when I at least test wires the readings I get should make sense.

Link to comment
Share on other sites

So after a little more digging I have found that a lack of continuity in the circuit for the fuel injectors. So I think I have a shorted Injector. The car ran terribly right before it died so I think this is a good bet. I have yet to find any bad wires or connections yet.

 

I am confused as how to go about testing the resistance across injectors. Is all one has to do is use an ohm meter across the injector terminals without the injector being plugged into anything else?

 

I would imagine injectors from 1992 would eventually die at one point.

 

Thanks in adavance

Link to comment
Share on other sites

 

Is all one has to do is use an ohm meter across the injector terminals without the injector being plugged into anything else?

 

 

 

you got it

Link to comment
Share on other sites

I have a hard time believing that... Did you test the injector or the wires to the injector? You need to test the injector itself... I believe you should be seeing numbers like 12.7 or so but that number might be for something else

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...