We have a 1990 that dies for what I thought was no apparent reason. The distributor has been changed. It's getting gas. Fuel pump seems alright. Plugs/wires are fine. We've had it on diagnostics and they come up with nothing.

It will be running just fine, then goes to actinig as if it's running on 6 cylinders, then dies. It usually will start back up~only to die again soon, but when it gets warmed up it dies sooner until eventually it won't start at all until the engine cools a bit (and it's not overheating either).


Please help!! It left me stranded at Sears Point during a race and I can't have that happen. I'm done racing until I fix it

 

possible computer dying perhaps.just a thought.if you know someone with another car maybe you can swap computers and see if that fixes things.

 

If that is the problem what $$$ is that to replace?

 

Let it warm up and get to the no start condition to run some checks.

Then check for a prime at the fuel rail after you turn the key on.

Then check for spark while cranking; a timing light will serve here.

Also, pull any stored codes.

 

All I'm getting is a code 12 and will do the other stuff in the morning. Thanks.

 

Code 12 isnt a code, it just serves as a refernece for the beginning and end of the trouble code sequence.

Check your Catalytic converter for being plugged. Also, check your fuel pump relay. Its on the firewall, drivers side, next to the winsshield wiper motor. remove the 2 nuts and pull the relay off. Check the wires and plugs on the bottom of it for corrosion, looseness, and cuts.

My car ran bad, and would stal lat anywhere near idle, ended up being plugged cat, and corroded Fuel pump realy wires.

90 model has precats. If one or both have goen bad, theyu could have plugged up the main cat.

Good luck.

 

Thanks, I'll check into that too.

Are these things that would normally be detected with diagnostics? I took it to a Chevy dealership and then to a buddy of mine that is very Corvette savy (races/owns 'Vettes) who owns a transmission shop and nobody could figure it out *yet*.

Thanks.

 

I had a 90, same thing. Its the PCM.

 

This is Mrs. ssmom13......what's the PCM? I'm sure my hubby will know but I'm interested as well.

TIA!

 

Again, what's the PCM? Where is it and how much $$$ to replace???

I'm sorry if this is a silly question, but I don't know.

 

The pcm or ecm is the computer. It is available at most auto part stores as a rebuilt unit. It runs about $100 more or less. You must exchange your old one for a core. They will charge extra if you don't trade yours. The ecm contains a "chip" inside. You will remove your chip and plug it into the new ecm. I am not saying your ecm is bad. If it is this is how you go about replacing it.

 

Thank you ;O)

My husband still needs to try the previous suggestions too. He was busy today and will do it some time this week.

 

I've seen it identified for the Saturn as PowerTrain Control Module.

Most of the Vettes folks refer to it as the ECM Electronic Control Module. It's the computer.

As far as where it's located, it varies with the year of the car. Some, like my 86 have them mounted under the dash on the passenger side behind what we refer to as the "bread-box"; later models have them mounted in the engine compartment. GM loves to change things.

Hope this helps.

Jake

 

Most often the cause is either ignition or fuel; occasionally both.

Most problems that seem to be fuel are, in fact, ignition, so that's where I'd look first. I would advise against throwing parts at the problem in the HOPE of correcting it. I'm a firm believer in diagnosing the cause then, if necessary, buy what parts are needed.

I not sure which ignition system your car has, whether it's Opti-Spark or HEI. If yours has a regular HEI distributor, I'd pull the module (under the distributor cap) and have it checked at one of the local auto parts stores. AutoZone and O'Reilly's (if there's one in your area) will check the module for free.

Some folks may tell you that the module is an "either/or" situation; either it worked OR it doesn't, but that's wrong. The module can be effected by heat/virbation and will work intermittently at times.

If you have the Opti setup, you'll have to seek help from the guys that are familiar with that system. I've never fooled with Opti.

You can mount a fuel pressure gauge and monitor it to see if the pressure drops just before the engine dies.

You can also run 12V directly to the ALDL to power the fuel pump which should bypass the relay and oil pressure switch pump circuitry. If the engine continues to run, then the fuel pump relay may be bad. I've never had to do that particular trouble-shooting procedure, but It's listed in my service manual for the 86. If you need me to post it, I'll look it up and post it.

It would be a good idea for you guys to buy a Chilton book that has the trouble-shooting procedures for all sorts of problems that you'll probably run into at one time or another.

Keep us posted.

Jake

 

Thank you Jake! I'll pass your suggestions on to my husband. He's working overtime most of this week so I assume this weekend he'll devote to figuring more out.

I'll keep you posted!

 

If all those check out, you can pick up a ScanTool at one of your local auto parts stores, like AutoZone, and plug it right in to the car's computer to read out all the sensor readings as the engine is running.

Remember, it's all about the numbers. All the sensors have a range within which they should operate when functioning properly. This range is expressed numerically. For example, the 02 sensor gives a mV reading of from about 35 mV to 900 mV or so when working properly and the readings should quickly cycle from low to high and back to low, etc. If it doesn't or is sluggish, then you'll know the oxygen sensor/wiring circuit needs attention.

When you plug into the car's computer with the ScanTool you can read the numbers for the sensors and can then tell if one or more of the sensors is operating out of its designed range.

Intermittent problems - those that don't cause a hard SES code to be stored - can be a bear to track down. Problems with the ignition module, fuel pump, coil, pick-up coil, rotor, bad ground connection, etc., are things that probably won't cause a code to be set. There are many others, too.

If you keep us posted on what progress you're making, I'll post the trouble-shooting procedures you may need to help sort this out.

Jake

 

When they replaced the distributer did they replace the mod inside. I had the very same thing on mine I would be running down the road just fine then it would start jerking then die. I would let it set for a few minutes and it would start like nothing was wrong then a few miles down the road it would die again. I replaced the dist cap with coil and the mod that fixed mine.also mine didnt ever throw a code. It looked thike they never used the heat grease under my mod so when it got hot it would die.