Sorry guys but ive been searching for a couple hours now and cant find what I am looking for. I have a 95 Z28 A4 mods in sig. I just finished putting a rebuilt engine in the car got it running good with open headers(had to relash the valves). I then proceeded to put the exhaust back on the car and now the car will not start. I did notice the fuel pressure drop from 39 @ idle to about 17 a couple times. However the pressure is currently staying at 39 @ idle and it stays the same with the vac line unplugged. im not positive but i think the fuel is not making it into the cylinder. I removed the #1 spark plug tested for spark, got it, however the air out of the cylinder only faintly smelled like fuel, plugs were not wet.

 

could this be the regulator?

 

If you have 39psi in the rails, fuel is available to the injectors.

I guess most people are a bit confused by your post, which may be why you aren't getting any responses. First you say "the car will not start", but then you say the fuel pressure is "currently" 39psi at idle. If it is idling, removing the vacuum compensation line should cause the rail pressure to increase by about 6psi.

Did you check the vacuum line for the presence of fuel? That would indicate a failed pressure regulator diaphragm.

 

i checked the vac line to the regulator, no liquid fuel but it did smell like fuel.


Sorry about the confusion in the post. the car currently will not start, acouple days ago it was running and that is when the pressure was 39 @ idle. Currently KOEO pressure is @ 39 PSI, pressure holds for a long time (no leaky injectors)

 

Are you sure you got all the gournds back on the engine? Did you check the Opti harness connectors for corrosion? Is the SES light on and have you scanned it for codes?

 

Im pretty sure i got all the grounds back on. the car has 2 ground straps excluding the battery ground one from frame to engine mount on the passenger side, one from the drivers side engine bay to the stud in the head by the ICM, also there are i think 4 smaller guage wires that are grounded to the same stud that run into the engine harness.

I have not checked the opti harness for corrosion. Ill do that in the morning.

I havent scanned the car yet Im still trying to figure out how to adapt my obd1 interface to the car (using shoebox's method) i think im having an issue with datamaster.

Anyhow I know the car threw at least one code but i was unable to retrieve it. The battery has since been removed to get charged, and the car has not ran since.

 

just went outside (burr its pretty cold for Texas) opti connections are both clean.

yesterday i put a timing light on the car it is getting spark out of the opti and at the correct time (i took the valvecover off to verify). i also took the # spark plug out put it to ground and there is spark at the plug.

i also took my DVM and probed the injector harness and they are firing as well.

this afternoon i went to the scrapyard and bought a known good (so says the scrapyard) regulator off a 96 caprice LT1. still wont run

 

anyone got any ideas?