Camaro won't start :( need help please :(

Okay- new to the board here... Hello. For Starters, I have a 1991 Chevy Camaro Z28... V8 5.0 L 305.. TBI, and it won't start. The fuel pump is not priming, the drk grn/wht wire from the relay has no power. The relay was replaced, fuel pump, oil pressure switch and connector... and still won't start... we used a jumper on the oil pressure switch connector and the pump came on and it started right away, so what would cause it to not start without the jumper. :banghead: Possible ECM malfunction? Something to do with the ignition switch? Or possibly just wiring??? Any help would be greatly appreciated. I miss my car :disappoin

Check in the engine bay near the battery cable. Actually along the battery cable (positive cable) there should a be a pig tail coming off of it that goes to a fuse holder. This is the ECM/Fuel pump fuse...check it.

I have checked a fuse mounted near the battery, in a little plastic fuse holding case, it's good. Is it the fuel pump fuse?

ECM and Fuel pump fuse.

Make sure there is power going through the fuse. After that you're going to need a wiring diagram to figure out where that wore goes and where it could possibly be "broken".
Another possibility is that the ECM is bad and not sending power to the pump. Since the car should start even without the relay working due to the oil pressure switch. As you crank the car oil pressure builds and closes the switch to power the pump. But since you had to jump the switch harness to get it running you may also have a bad switch.
To clarify, the ECM powers the relay to run the pump for the 2-4 second prime and during cranking until oil pressure closes the switch which then can override the ECM's signal.

Right, that's why we really thought that replacing the switch and harness would work, the oil pressure switch connector was melted and one of the terminals were burnt, so we thought that was the problem. Don;t understand why it work work when we used a jumper from the harness, but then won't work with a new switch. Any suggestions?

. Don;t understand why it work work when we used a jumper from the harness, but then won't work with a new switch. Any suggestions?
The only explaination I can offer on that one is that you aren't building enough oil pressure to close the switch. It takes about 7 PSI to close the switch.

Let me check a few more things then i'll repost, make sure my new connector has a good connection.

had a similar problem myself. in my case the wiring to the oil pressure switch had touched the exhaust and welded itself the the headers causing a short in the circuit. (it cost me a lot of money to tow my car 125miles, cuz i couldnt figure it out on the spot)

check for that.

otherwise get a mechanical oil pressure gauge so that you can see it in action as the engine is cranking.

is your fuel pump relay wired correctly? (you didnt splice any wires did you?)

try another switch, i think they are around $12.

Well the oil pressure switch was fine, and we replaced the connector to the switch also, the problem is somewhere in the relay, the wire that is suposed to prime the pump, wouldn't come on. But yeah, the relay was wired right. It's been rigged as of today. We've bypassed the relay and hook up a toggle switch...turn the switch on to turn the pump on... start the car.... turn switch off... simple, and it works... car is up and running, just a little rigged but that's ok.

the best anti-theft device ever. no fuel pump. lol

That's exactly what I said, see the whole two birds with one stone thing, is exactly true in my case. When I bought the car the VATS was bypassed so I have no VATS or chip key, so now, My car runs, and I have a ghetto anti theft device in my car. :grinyes: now... how do i post pics?!?

That's exactly what I said, see the whole two birds with one stone thing, is exactly true in my case. When I bought the car the VATS was bypassed so I have no VATS or chip key, so now, My car runs, and I have a ghetto anti theft device in my car. :grinyes: now... how do i post pics?!?How would one go about bypassing that switch?

What exactly are you wanting to bypass?