rreid

89 Camaro IROC-Z 117,000 Miles. 5.0 TPI motor, 5sp manual tranny.

Okay, here's the story... It started running rough last summer. Idle was fine, and seemed to rev fine, but when I let out the clutch and gave it gas, it would start to chug.

It would pick up at about 2600rpm, then power would drop off about 3000rpm. I replaced the fuel filter (fuel line was pressurized, so I didn't think it was the pump, plus when I removed the fuel pump fuse, it got worse).

Checked all fuses, replaced plugs, wires, cap, rotor to no avail. Then, days later, pulling into my driveway, it quit. Hasn't started since.

Parked it for the winter, then just tried replacing the ignition module. Coil is fine (tested for spark).

It cranks, fires, runs rough for three seconds, then quits.

I checked the timing, and it was slightly off (about 2 deg) - it should still start right? What else could it be?
BTW - no SES light. But, I did check for codes by jumping the 5&6 pins on the diagnostic connector. According to my info, it should flash '12' three times, then flash any codes. But it just continues to flash 12. I don't know if this is telling me there are no codes, or that there is a code 12.

I found a list where code 12 is described as "No reference pulses to ECM" Could this be telling me that my ECM is shot? Or is there a connection somewhere that sends these pulses that could be gone?

I'm new to this site, but have had my Camaro for about 11 years, and its never given me this kind of trouble before. Does anybody have any suggestions as to what else to test? (And how to test it?)

Mike55TPI

Code 12 is telling you there are no codes. I would check the resistance on the injectors. They should be between 14 and 16 OHMS. A bad injector will do exactly what you describe. When I have one do that on the road I unplug each injector one at a time. If one is dead, when you unplug it the car will run pretty good albeit on 7 cylinders. The second thing that comes to mind for me is the fuel pump. They will die without much warning sometimes.

rreid

I just spoke to a 'Camaro specialist' (he claims), and he's suggesting replacing the entire distributor. If I get a timing light to flash on each cylinder, wouldn't this tell me it's not the distributor? He also suggested checking the fuel pressure, but can I do this just by cranking or does the engine need to be running? Since I can't get it started...

D's89IROCZ

I would hold off on the distributor . Other stuff to check first. whats the fuel preasure , when this happens?

Mike55TPI

D's right. The fuel pump is electric, so just turning the key on will bring the pressure up if it's working. No need to turn it over. Point in fact, if you remove the gas cap and put your ear near the filler pipe as someone else turns the key on you should be able to hear the pump run.

Red Devil

Unplug your MAF or swap your MAF relays and see what you get.

rreid

Thanks for the suggestions. I have pressure in the tank, twice I opened the cap and had a release of pressure. However listening is a good idea, I didn;t think of that.

I decided now it needs a mechanic to diagnose it, I just don't have the time or the tools to keep checking. It has been a exhausting experience, and the car had to moved off the driveway to make room for our travel trailer. We had it towed to the shop.

I will give the suggestions to the mechanic, thank you for all the assistance.

rmchugh

a few years ago i had very similer problems the cucgging, loss of power etc. i changed the distributor and it was night and day. but that was just my experince.

Evil 88IROCZ

Hey three reasons the car is not starting. Air, fuel, spark. You can eliminate one cause you are still breathing. Check for spark on the coil wire, then check the spark to some individual cylinders. If you have no spark from the coil check the wires (coil to the distributor) that clip into the coil, mine were slowly breaking away and would give me a bouncing tach, horrible idle and power and eventually a no start. If you have spark at the coil but not at the cylinders it is most likely the distributor. Now if you have spark check for fuel. Get a fuel pressure gauge and see what happens when you turn the key to IGN. you don't have to start it. If the pressure is low then its the pump, if you have pressure and still no start. Check the ohms on the injectors, and check the wires going to the injectors to see if the ECM is trying to fire them. Sounds like the fuel pump to me, our cars are famous for it.

rreid

Thanks, guys. It was the fuel pump. Seems it was giving me low pressure, then cutting out. The shop did some tests and replaced the pump. Runs like a dream now, since it basically had a complete tune-up. I was told that the reason these cars go through fuel pumps is because they are stationary pumps, so when you are low on gas and you corner hard, the fuel sloshes to the side, but the pump stays in the middle, and you effectively starve it. This is worse than running out of gas, because it can happen many times without you realizing it. The best way to avoid it, obviously, is to keep the tank above half full.