Dark Zeiro

Hi i need help with my 94 z28 lt1 f-body i bought the car a few months ago from a friend who put a 96 lt1 with the BBK throttle body(unsure if the are diff ones) from another camaro in it not first to say i did drive it and it drove fine but it had to warm up a little to stay running. a few days after i bought it it wouldnt stay running for very long it would start up then die but sometimes it would start stay running for a bit(10-20 min) then idle funny then die. so as a person should do with the lt1 and start at the opti so i put in a new opti with new pump seals on the pump, new spark plugs but not the new wires(yes gapped correctly)and since i had the stuff out i put in a new IACV and MAF cuz the screen was gone and new battery since i got the car cheap. {it also has had the ac and EGR removed but not scrubbed off the PCM.} After i put all that in it starts faster and runs stronger.....for how little it does, now it will start strong but runs a second and then slowly dids off. so any info help things i my hav missed with the PCM that the 2 years hav diffrent. and no i cant get codes cuz the car wont run long enough to get them i hav tried. so please help THANK U TO ANY AND ALL THAT DO!!

Injuneer

The engine doesn't have to be running to scan for codes. What did you use to try and pull the codes? That should be the first step with an LT1 (or any computer controlled engine). At any point have you checked the fuel pressure?

Dark Zeiro

i work at a dealer ship and alot of the guys hav the scanners but i made the mistake of trying to change the battery before all other things cuz i had the battery tested at work and it was bad(mind u it was before i didnt know that it doesnt store codes after unplugged) so i replaced it. then tried and got no codes to come through i even tried a basic code reader to test the chance of faulted equipment. and i just got a pressure tester, hooked it up right before i had to work and turned on the key but the needle didnt move after the pump turned on, not sure if i didnt get it in tight enough(should it be tight tight?) or its just getting no pressure at all but am goin to try in the am again to see.
thanks for the responed btw.

Dark Zeiro

ok update got bored and tried the pressure test again the pump must be shot when i turn the key on the pump primes goes up to 1-3 psi and when the pump stops priming it goes to zero i tried it 5 times to be sure.

Injuneer

A "test" fuel pressure gauge will have a pin in the connector that depresses the pin in the Schrader valve. If the valve pin is not depressed you will not get a pressure reading.

Sounds like you got a reading though.

There is at least one code that will set with the engine only cranking, not necessarily running. DTC 16 sets if the PCM can't find the low resolution pulse signal from the optical cam position sensor in the Optispark distributor. When that code sets, the fuel system is disabled. But that would not prevent the fuel pump from priming.

If the GM dealer mechanic was using a Tech-1 or Tech-2, the results are valid. Unfortunately, there are other scanners like the Innovas that give bad results. And if the "basic code reader" was something like the $30 Actron that shorts the pins in the ALDL connector, that won't work on any LT1 after 1993.