Hello everyone, I am in need of help something terrible, I am working on a 1971 Chevelle with an Lt1 Engine and it ran excellent for 15 years then died on day and now won't run at all. It will start but will not stay running, it back fires and will not rev up at all. I replaced the fuel pump, the fuel pressure gauge says it has 42psi, I have looked and can not find a vacuum leak, I am totally lost, Can anyone help?
I replaced the spark plugs, wires, checked the rotor bug, inductive pick up and lots of other stuff. As long as you don't touch the gas pedal it cranks fine and tries to start, if you touch the gas pedal at all it sounds like the engine is way out of time or trying to hydrolock. I checked the timing and it is correct. I unplugged every sensor I could then tried to start it and the symptom did not change at all. If someone could help me it would be greatly appreciated.
it has an OBD system with the rectangle diagnostic plug with squared corners but the engine says it's a 1996 I think, I don't understand. :-(
Charles

 

Welcome to CamaroZ28.com!

Best place for tech help would be LT1 Based Engine Tech. I'll move this post there for you.

 

optispark maybe?

 

Sounds like someone used a 96 engine with an older OBD1 harness. If you pull the PN from the PCM you can verify it.

Does the PCM have any stored codes or do you have any way to scan it to see what it's doing?

 

That's what happen to me when my map sensor blew.

 

Sounds pretty similar to both times I had an Opti fail.

 

You need to identify the year of the PCM and wire it correctly to the ALDL connector. Then scan it for codes. Guessing is a waste of time.