I just got my new engine set in, im putting a tpi on my 91 that was tbi. I converted a 89 mass air to map. It will crank but will not start. This is not my concern right now. While diagnosing the no start, my oil pressure guage reads zero while cranking, so I checked my connector and tried to start the car with the connector unplugged. CAR WILL NOT CRANK UNLESS THE OIL PRESSURE SENSOR IS PLUGGED IN. I want to figure this out before i go any further into the no start. Any ideas? I did find that the signal wire is the problem, if I connect the sensor, but unhook the signal wire, it wont start. If I hook it back up volia it cranks......... I have no idea where to go from here.

thats becasue the car need it in to run ... why would you want it out anyways huh ?

Leave it plugged in

Well im diagnosing another problem, and I think the two could be related. I would like to know if the starting system and oil pressure sensor have anything in common? Is this a normal condition for a 1991 camaro? I dont know this is why i am asking.................

check all your grounds and what not. disconnected oil press sender had no effect on my setups. It is only connected to teh gauge cluster.

I have looked over many schematics and it doesnt make any sense. Atleast now I know that it isn't right. Im gonna go and do some more checking. thanks for the reply...

Okay, I'm a little confused. It won't crank or it won't start? You said both but which is it? If it is that it will crank but won't start that's easy. The ECM shuts off the fuel pump if it doesn't see any oil pressure. It's just a built in fail safe. If it is that it won't crank, then I don't know because that should have no effect on the starter.

Nope, ECM and oil pressure switch don't talk to each other.
(switch and sender are 2 different parts on certain years and is one part in later years, and does the same thing as the 2 seperate parts)
Oil Pressure switch is wired in parallel with the Fuel Pump Relay.
It is a secondary power feed to power the fuel pump if the relay fails.

Well the concern is that it will not turn over. I still don't know why but I bypassed the starter enable relay and it turns over just fine regardless of the oil pressure sensor. As far as the no start i think I found the problem. All eight fuel injectors pintle valves were siezed. Got those cleaned up at work today will see if it will start tonight.

Yes you are right, I apologize. I forgot all this stuff I guess. I've spent too much time around Porsches.