I've had a problem for about a month now with getting my car started. Details about it are in the TBI forum under my thread called "Still No Start".

Basically the short of it is my injectors aren't firing and I am getting power to them by hooking up a test light to the hot wire in the connector and grounding the other wire to my engine block. That lights up the light just fine but when I hook up the test light to the connector (both wires) and crank the engine, the light doesn't pulse or anything.

I got a brand new ECM about a week ago but I still used my old chip in it. I don't quite understand PROM burning, much less what the PROM does but I assume it controls a lot in the engine, including the injectors. Could it be possible that my chip went bad? The car started back in June but I took out a few parts of the engine (like battery and radiator) to get it painted in September/October. I got it back on October 25th and it hasn't started since.

So, is there anyway for the PROM to go bad onmy car? If not then I'm not sure why the injectors aren't getting the signal to fire. I do have another question though.

If the chip has gone bad, a friend of mine gave me his ADS SuperChip. He had a TBI as I do, but I don't recall the size engine. I haven't put the chip in yet because I just got it but it should theorhetically work in my car right?

 

Couple of things can be done to check out the chip. First is to look for the SES blink at key-on, engine-off. Key needs to be off for 10 seconds before each check.

A properly running ECM will have the SES: turn on, blink off, then turn on solid. The blink off is what to look for, no blink off, Bad ECM or PROM.

Second thing you can try is to remove the PROM and try to start the engine. This puts the ECM in back up or limp mode. Need to leave the CALPAK in place, so don't remove that. Only remove the PROM.

RBob.

 

with the key on, engine off the SES light turns on, blinks off for 1/2 second, then turns solid.

I haven't tried withthe PROM out yet, I'll go try that now.

EDIT: Nope, it still didn't start

 

OK, that rules out a bad PROM and most likely out a bad ECM.

If you squirt some fuel into the TB, the engine runs(?). If so, then . . . At this point I would suspect a bad ignition module. The reason is that the ECM needs a distributor reference pulse (DRP) in order to fire the injectors. And, ignition modules are known for this failure mode. Where they still fire the coil but don't pulse the ECM.

Or, there is a wiring issue between the distributor and the ECM. This would be with the 4-pin connector at the distributor.

RBob.

 

Without DRP's from the ignition module, the injectors won't fire. Check the wiring at the distributor and if all checks out, you might try replacing the ignition module unless you have an oscilloscope handy to check for pulses. Lastly, the pickup coils in the distributor have been known to fail as well. It is not too common but it does happen. HTH

 

RBob, what 4 pin connector are you talking about? I don't see it yet, where is it located?

 

I believe your engine has the small cap distributor with a remote coil. With that setup there are two connectors that go into the base of the distributor. Actually they are directly to the ignition module that is in the base of the distributor.

One connector is a 2 pin and goes to the coil. The other connector is the 4-pin and goes to the ECM.

RBob.

 

Oh, you mean the connections on the ICM itself?

I just got back from getting the ICM tested and it checked out fine.

 

I've known the ignition module tests from the parts stores to be unreliable.

consider grabbing another ign module from a junkyard car, they are pretty common and were used from 1985 to 1997. Everything from v6 fieros to big block powered trucks used the same module. Try to get a newer (90's) true GM module. the aftermarket parts store replacements are usually not as good.

 

Well an update. Thought I had it almost fixed yesterday. I was getting fuel spray but the darn thing wouldn't start still. So I thought maybe I fouled the plugs or something so I checked and I wasn't getting spark. So today I replaced all of the spark plugs and wires. Reconnected everything and now I am getting no fuel out of the injectors.

It has to be some sort of short somewhere, my guess is at the ICM whether it be the connections behind the ICM or the connections going into the ICM.

91L98Z28, I might go do that this weekend.