Ed87camaro

Hey all, I am new to this site and I'm having some serious issues with my 1987 camaro 305 TPI.

Ok heres some history. First, it needs to be noted that a previous owner definitely made some performance modifications, and not very well (I.E brake booster, shift kit, performance chip in the ECM, terrible wiring). At one time the car ran great. But now it was having a really rough time starting. Once it got started I could keep it running and it ran OK, yet still rough and hesitant. Could restart it within 5 mins but if I waited longer it would take time to crank. I started looking into checking the threads here and just kept finding more and more issues with this thing. Heres what I have done

Put a new Distributor cap and rotor on, needed it anyway. And then I tried to set the base timing just to be safe before going to test the TPS, IAC, MAF sensor, etc. Reading here to unplug the wire to put the car in bypass mode before the timing is what I tried to do, and realized the check engine light wont even come on. I manually tried to put the ECM in Diagnostic mode with the jumper and nothing. I pulled the ECM out, found the pinouts and validated the grounds were OK and the battery supply was there. It seemed to me that all the battery power voltages within the two connectors were fine. There were some that didn't match exactly, and I can get more specific if needed.

Also, I tapped the fuel rail and read the pressure, and after the car was started it ran at about 38 PSI steadily, and held the pressure for a while after the car was off. Im pretty stumped, I even had another ECM from an 89, (both are 1227165) and put that in and still couldn't get the diagnostic mode or the check engine light to even come on. Can someone help me out with some troubleshoot steps? Thanks

Ed87camaro

More information, I have checked all the fuses under the hood, all are okay, and the ECM 20 Amp in line fuse near the battery. The three relays are tricky, because I dont know how to test them, or what each of the three are. One says MAF Power, and then I have two other relays.

Moreover, in my novice approach to this I unplugged the ECM completely and tried to start the car. It wouldn't fire as I didnt think it would since I am creating a giant open circuit in the harness. But when I plug it back in and spray some starter fluid in the intake it turns over and stays running.

ninetyone

iTrader: (2)

i hope u are checking fuel pressure with vacuum hose unplugged and plugged on each end (meaning plug nipple on intake plenum and plug hose on the pressure regulator. This simulates WOT fuel pressure. As for your check engine light. Second of all you are jumping pins 5 &6. Or A & B. On the older cars like yours IIRC it should be the pins 6&12. https://www.thirdgen.org/service-eng...ht-error-codes.

ninetyone

iTrader: (2)

Set fuel press to 43.5 psi. Also if ur SES light is not working ,check the bulb too. If that isnt it you may need to look at the C207 connector near the ecm. This is part of the harness that goes out to the gauges,cruise ,ect. It is is the clear plastic bulkhead connector.

ninetyone

iTrader: (2)

ohm ur fuel injectors and check your MAF meter. They are known to go bad .

Ed87camaro

Checking the Fuel pressure I did not take off the hose going to the Fuel pressure regulator. I also had no priming of the engine within the first two seconds. I will have to re-try taking the measurement as I only plugged the nipple into the tap on the fuel rail. As stated when I did this it remained at about 38 PSI as long as I didn't throttle the engine. Was I supposed to still see the engine prime when I did it the wrong way?

I think the previous owner got rid of the cold start injector. I have what looks to be the plug for the injector just laying on top of the engine. Not sure if that changes what I should be looking for.

For the diagnostics, I was putting a jumper between A&B (5&6) but not (6 & 12), I will try this today, and if nothing then I will check the bulb, and continue to ohm everything out from there. Thanks for your help, it is much appreciated.

Ed87camaro

Just tried out pins 6 & 12 and 6 & 5 for diagnostic mode, and nothing. I still have only the Fasten Belt light that comes on, for different increments of time, every time I turn on the ignition.

Do you know where I could find the ohm values to ring out the connectors?

ninetyone

iTrader: (2)

yeah for fuel pressure. You need to disconnect the hose that goes from the pressure regulator to the plenum,then basically plug the hose and plug the nipple on the plenum too. If you don't do this the fuel pressure will read lower like 38psi or so. Not sure about the ohms or volts for checking your light,sorry. I do recommend ohming your injectors tho. Key on engine off.

ninetyone

iTrader: (2)

https://www.thirdgen.org/forums/tech...t-working.html take a look at this link too.

Ed87camaro

Thanks ninetyone! Ill hook up the pressure gauge correctly and ring out the injectors. Im assuming you just mean to take the connectors off and ohm them one by one? What value should I be looking for?

ninetyone

iTrader: (2)

http://www.youtube.com/watch?v=lKKhYJd1gzg

C409

iTrader: (5)

......... Check for a good bulb in the SES light ... try a new engine coolant temp sensor ... they're around $10 ............