So I have a 91 camaro rs tbi 305. Over the 3 years of having the car I’ve learned a lot about tbi systems and 3rd gens as well. I’m thinking I’m having an ecm problem or an injector problem. First things first here’s a list of things I’ve replaced either as preventative maintenance or because it went bad.

New fuel pump with a new sending unit
New distributor complete with new pick up. ICM. Rotor. And cap.
new spark plugs and wires
new starter
new o2 sensor
new oil sending unit
New coil.
new temp sensor
new tps
new aic valve
new map sensor
new fuel filter.
Ive rebuilt the tbi unit. I didn’t replace the injectors but I cleaned them and put a new one of those little filters that go on the Side of them.
ive bypassed the vats with a resistor and the security light still works like it should
ive made sure it’s getting fuel all the way to the TB.
and my fuel pump is definitely kicking on.

so my problem I’m having is very random and seems to happen more often in the heat or when it’s been driven. So I’ll drive up to the store and turn the car off the. It won’t start back up. Cracks and cracks. And isn’t getting any fuel spraying out of the injectors. Not even a dribble. So I don’t think they’re clogged. I could let the car cool down for a few hours to a cold start and it would fire up and run great. Now it won’t start at all. I’m wanting to say it’s the ecm because of how erratic it is. And how it’s slowly gotten worse. I know I’ve read that the grounds can be a big issue but I have no clue what grounds I need to check and where they are located. Also how would I check the ecm? All I have is a cheap multimeter. I’ve read a few post about using a noid light but I won’t be able to until I the morning when the parts stores open. Any help would be appreciated. I’m at a loss.

 

Do not use a multimeter unless you are sure of it ohm impedance. I think it needs at least 10,000. The volt meter could cause damage. A scope or a fine inductive amp meter is the only other ways I am sure you can safely test it. The key is not to draw too much power. Do not use a light of any kind unless it was designed for it .

If this came into my bay I would check for fuel pressure and check for signal with a noid light. If you do not have pulsing at the injector I would suggest a repair manual because you are a long way from proving ECM. You should check the resistance of all the components. If the resistance in the circuit is too high you can fry the new ECM.

I theory and inductive timing light may show on-off power with out hurting the circuit. I am not sure it would work but the pick ups are the same design as the inductive meter on my scope.