I have 1991 RS Camaro TBI with 305 V8. Car has been starting up and driving good until yesterday. Now it only wants to crank but not start. Every once in a while it will start up but idle rough and cut back off. I don't know what the issue is. Last night I totally tore down and rebuilt the TBI and this morning it started right up and ran strong. Now it is back to doing the same thing again. Anybody know of anything i can do or any know issues. Thanks

 

Are you missing fuel, or spark, or both?

What is your fuel pressure? When was the last time the vehicle received a distributor cap, rotor, plug wires and spark plugs?

What is the coolant temperature sensor reading compared to ambient temperature?

 

I have found out that I am missing fuel, I'm getting fuel to the TBI but nothing they injectors also their is no power to injectors. Something is taking power from injectors. What would cause voltage to be cut going to injectors?

 

The injectors should be powered by separate fuses. Start there. The ECM controls the ground, which fires the injectors.

 

I have checked the fuse for both injectors and they are good. I also checked the wires for continuity from the fuse block to the injectors themselves and they are good. And i am getting voltage to the injectors from the fuse block. Only thing that threw me off was that regardless of which wire coming off fuse block to the injectors both 1 and 2 they had continuity and voltage to both, so I'm assuming they jump each other at some point. Regardless I have power. So the issue must lay with the ECM. Is it a common issue with ECM to only go bad so that the injectors are the only thing effected? And is it still possible that the VATS system could still be the culprit?

 

What did you fix to restore power to the injectors?

Do you have spark?

 

I have spark just no fuel to ignite. I had power on the hot side of injectors all along. I misspoke earlier. So I'm still guess ECM is issue

 

ECM, wiring to the ECM from the distributor, wiring from the ECM to the injectors. While unlikely, you could have two defective injectors.

I'd be checking ALL the fuses.

What is your fuel pressure?

Connect a scan tool, see what you get from the data stream.

 

When it's a VATS issue engine won't turn over at all. You don't seem to have that problem

 

I checked every fuse already. I was checking wires from distributor to ECM and ones from ECM to injectors for breaks or damages and they all have continuity. I checked the 2 grounds on the ECM and they are good. I have continuity thru the 2 ground pins on ECM. This is the part I can't figure out and why it has me thinking bad ECM. As soon as I try and start the car the grounds at the injectors are no longer grounded. It is almost like the ECM is taking away the ground now instead of suppling it. If that makes sense.

 

I didn't think so. I am just trying to wrap my head around the issue. I never had an issue what so ever. Then one day this **** starts happening. It is so strange cause it will start right up sometimes out of the blue, then bam it just cranks but wont fire up.

 

I think you are having a VATS issue or Oil pressure sending unit issue.

I had a similar problem and have EBL Flash. I disabled VATS in my ECM and bypassed the starter enable relay behind the drivers side kick panel. Easier than new ignition switch and matching resistor key.

Also could be your oil pressure sending unit. The fuel pump relay gets power thru it.

 

Nope. The fuel pump can get power through the oil pressure switch. The oil pressure switch will bypass a defective or incorrectly-powered relay. A failed oil pressure switch won't cause a no-start or a stall, if the fuel pump relay and harness is working properly.

In other words, lack of fuel pressure cannot be caused by a defective oil pressure switch or harness, unless the fuel pump relay or harness is also defective.

If the fuel pump relay or harness has a defect, there may be a delay in fuel pressure until the oil pressure builds up high enough to trigger the oil pressure switch. When the oil pressure switch closes, the fuel pump will run.

I've asked twice "what is the fuel pressure" but I don't get a response.