I have an 89 gta with 77,000 miles its always ran like a champ until a couple months ago. While returning home from a weekend trip about fifteen minutes outside of town the car suddenly lost all power rpms dropped and it died it would only crank over but not fire i towed it into a shop after playing around with it for a while they said i had 3 bad fuel injectors and a bad computer not having much cash they said if i replaced the computer i could probably make it home at least (2hour drive) so thats what we did i got out in the country 15 mins away and bam it fell on its face again but did restart only to die 45 seconds later then would only crank but not fire up so we towed it again replaced the faulty injectors and i made it home fine and drove for a couple weeks trouble free then when leaving town again i got about an hour away and the check engine light came on all gauges read fine i pulled over checked fluides all seemed ok i started the car and turned around and went home issue free it ran fine no check engine light i checked the code and it said low vacume asociated with the egr i forgot the code # but i drove for a couple more weeks trouble free then yesterday after racing(and winning) i was driving around town and stopped at a stoplight i glanced at my gauges and my oil pressure was allthe way down!!!!! as soon as i noticed the car shut off no smoke no funny noise just died it still cranks but wont fire over the oil pressure builds when cranking so im a little confused it doesnt leak any oil or sound as if the engine is mechanically damaged i didnt check fuel pressure yet but when i pressed the valve on the rail fuel sprayed out any suggestions would be helpfull i need to get her back on the road.

 

If the oil pressure sender goes it tells the fuel pump, hey buddy no oil not good. It turns off the pump to prevent driving with no oil pressure. Try a new pressure sender

 

Ive considered that but the rail seems to have fuel pressure althought i havent tested to see exactly how much.

 

The rail will still hold pressure.

 

Common belief, not entirely true. The oil pressure switch is merely a backup to the fuel pump relay. If the relay fails, the OPS powers the pump.

 

I played with it a little more last night it is getting spark and it is getting fuel to the rail but when you turn the key forward it has no check engine or other lights besides the seat belt and security which turn off after a few seconds also when you put a jumper in the terminal it doesnt flash the check engine light the light just worked prior to the car dying so im going to assume i may have burnt another computer and there must be some underlying reason it keeps doing this. Any insight would be helpfull.

 

Ahh I learn more everyday. anyway, could be faulty ecm or prom

 

I was under the impression the switch controlled the relay directly to shut it down if pressure dropped also.
What I found when I rewired my car was that the distributor reference pulse also triggers the ECM to turn on the fuel pump relay.
As long as I get a distributor pulse, the pump relay stays engaged via the ECM output for two seconds (aprox).
The switch will only provide backup if the main relay goes bad (like Stekman stated).
There really is no "protection" so to speak for running without pressure.
Just an indication its not there.
If the ECM would not keep triggering the fuel relay, it would work to save the motor.
JP

 

IM now totally stumped, when the key is forward i noticed there are no lights on on the dash except the security and seat belt which turn off after a couple seconds. the fuel pump is not engaging!!but when you apply current to the bottom left terminal on the diagnostic port it engages the pump, but when pressure is built it still doesnt fire so im assuming the injectors arent fireing it does have spark but the plugs are totally dry. Any suggestions would a bad ecm do this ?? or is it maybe a short to the ecm or bad ignition mod??? Im lost last time ecm burnt symtoms were slightly different it had ignition lights and fuel pressure, just no injector pulse.HELP!!!!!!!!!

 

bad ignition module wouldnt have anything to do with it. Its an ECM related issue if your not even getting a steady SES light on during the time the IGN is in the on position. swap one out and try.

 

Yeah no ses light at all not even with a jumper in the diagnostic terminal and its not activating the fuel pump. Ill probably try to borrow a junk yard ecm tonight unless theres any other link to the ecm i can check??

 

Stupid one but a good idea

Check the grd on the pass cyl head :-)

Does lots of dymb things when loose or not connected, also check the drvr head grd while youyr poking around.

Bad or dieing ign switch can wreak havoc as well :-)

later
Jeremy

 

If you were able to apply power to the ALDL and make the fuel pump turn on, then that indicates the relay is OFF.
That indicates;
a.) ECM is not outputting the signal when recieving a ref pulse from the distributor.
b.) just a bad relay
c.) oil switch is bad and not connecting up the fuel pump when you actually have pressure.
Your problem may be the relay AND the oil psi switch have both gone out on you. If the oil switch has been pulling all the duty of running the pump, its highly possible. (previously did it seem to crank a long time before starting?) Should fire within the first rotation or so.
It doesn't explain the injectors not firing, a noid light is the best help there. For the few $, its worth having one.
I didn't think 89 had VATS. That will not allow the injectors to fire if not getting the right signal.
Also check to see if maybe the memcal has come loose and wiggle all the ECM connectors.
That will obviously cause you problems if everything is not touching.
Hope that helps,
Jp

 

Right. The 1989 GTA does have VATS. Maybe try another key? Allen

 

If you have one.
You could always trace the wires back to the VATS module and jumper in a resistor (of the correct value).
A spare key would obviously be easier.

 

WHOOO its fixed, i found an inline fuse under the hood it wasnt where it was supposed to be but when i found it it was blown so i replaced it and cranked it over and got a cloud of smoke from under the car it came from the oil pressure sending unit replaced unit car running good. Thanks a lot for all the help guys you saved me a lot of cash and the hassle of dealing with shady shops.