My Camaro died at the bank drive-through Friday before last. The starter will crank the engine over, it has spark but no fuel. I've hot-wired the fuel pump to test it, checked all of the fuses and the relay, and the battery is perfect. I tried to pull a code from the ALDL and got nothing. To be sure it wasn't a bad SES bulb, I pulled the instrument panel out and put a test light to the connectors, nothing! I thought the oil pressure sensor would turn on the F/P relay if it had at least 4 psi so why can I not get the fuel pumping? The filter is recent, the wiring is good, I'm at a loss! HELP!!!

 

Quote:

why can I not get the fuel pumping?

Does this mean the fuel pump isn't working, or you assume it isn't because you're not getting any fuel?
Have tested for fuel pressure?
Can you hear the pump prime for a few seconds with the engine off and the key on?
There's a pump test terminal on the ALDL connector.
Will it start if you drop a little fuel into the intake?
Could be the ECM, the ICM, injectors drawing too much current, clogged fuel system, or faulty wiring.
have you checked the injectors for 12volts, and their fuses?
Will it start if you drop a little fuel into the intake?
There are other things, but the above is what I would check first, instead of replacing parts, the ICM in the dizzy can be tested at a parts store, could test good cold, but fail when hot, same for injector coil resistance.
If it has VATS the injector enable signal from the module to the ECM could be faulty.

 

well obvious is to check fuel pressure at the lines, if you have fuel pressure then go from there
definitly pull your injector wires like he said and wth a V meter check to see that they all have the same draw

i just had a fun nightmare chasing messed up wires through my harness, i know theres a wire that goes from the back of the ignition conrtol module, to the computer that gives pulse reference for the injectors, my fuel kept cutting out on me cause of that wire, so it could have something to do with the module, id think thatd throw a code tho

 

Sorry, I didn't fully explain what I've already done... It will fire briefly when fuel is dumped into the TBI unit while cranking, there is no pump function or current at the relay connectors. The computer is displaying no codes at all, even a "12" code, nor does it even light-up when ignition is put in the "on" position. I thought even a faulty ECM would give a code as long as there is battery power. I will be tracing the ECM power circuit tonight...

 

Fuses?

 

Knowledge and experience is all I can offer to help troubleshoot.
As old as our cars are wiring can't be excluded as a trouble source, but I give it a low priority.
A no SES light is either a bad bulb, or a dead ECM (, or no power.)
A manual prime causing the engine to run briefly is not proof that the ECM is functioning because the ECM doesn't take control until the rpms reach a preset level, and it doesn't prove that the fuel pump is bad.
This is why proper fuel pressure must be verified, use the "Pump Test Terminal" on the ALDL connector. Apply 12 volts to the ALDL "G" terminal.

 

I have no fuel pressure and no pump function. The bulb for the SES light is good and I even removed the instrument panel to check the connectors. I need to check the 340 & 439 circuits for continuity but it's all pointing to a bad ECM so far. I will put voltage to the "G" terminal to make sure I have a good circuit there as well before final diagnosis. Thanks for the input!!!

 

Did you try and put a 'noid light on an injector and see if it is getting pulses while starting?

 

ok, here goes...

you got no fuel pressure and no pump function. momentarily, put the possible ECM issue to the side, heres what i want you to do. pull the fuel pump relay so you have access to the connector. you got 5 wires, labeled A,B,C,D,E. the fat tan/white wire goes from the relay in pin A to the fuel pump, if you put 12v to that wire the fuel pump will turn on, provided the fuel pump is good. id do that first and eliminate the fuel pump right away. pin B is a black or black/white wire, thats the relay ground, so make sure you got continuity between that and a known good ground. pin D is a red wire that goes from the relay to the ALDL connector, thats the fuel pump test wire - dont worry about that. pin E is power to the relay, orange wire, hot at all times. make sure thats hot. finally, you got pin C. its a green or green/white wire. it goes from the relay to pin A1 on the ECM. with the key on it should read 12v. pin C is the key here. if the key is on then that pin is hot, no excuses. if its not you're looking at either A. loss of power to the ECM(fuses?) B. loss of ground to the ECM or C. a bad ECM.

someone posted something about a noid light to check the injectors. 99% of people don't have a noid light. heres what ya do. with the key on, take a voltage reading between the injector and ground, you cant test across the injector because the ECM grounds it, its hot on both terminals. youll have 12v at the injector. start the car - check the voltage at the injector again. itll be less than 12 volts with the car running. for example, with the car running, itll read 8v. reason for this is: a multimeter can't read pulse width unless its specifically set up to do so. so on the vDC setting, with the car running and you probing the injector, the meter will average the pulse width. its seeing 12v - 0v over and over again in rapid succession and it cant read that fast, so it averages it.



smith

 

I bought a factory service manual from bishko books on eBay (beautiful, all new reprint for $90!) and traced circuit 340 which supplies power to the ECM, fuel pump relay, and oil pressure sender. It was the junction block right next to the battery! I had some wiring for my foglamps get chaffed, it shorted, and melted the junction post (but no other wires thankfully)!!!
Thanks for the input fellas and now that I have a very detailed manual hopefully I can help others with their cars!!!
THANKS!!!

 

glad to hear it!