My 1989 2.8l Firebird has developed a no-start issue. It has spark and I am pretty sure I hear the fuel pump priming, but it won't catch. Before this it was sputtering intermittently around 1500-1800 RPM.

In my diagnosing I was looking at the oil sender switch and all 3 prongs on the harness have continuity to ground (ignition off). That doesn't seem right. Can anyone confirm that's incorrect? I was expecting one to have continuity to ground, one to have voltage, and one to be NC in off position... I would also like to know which two of those connections to jumper to bypass the oil pressure sender. I searched the forum but couldn't find wiring info for this switch.

Thank you very much for any help on this.

 

Let's see.....

If you hear the fuel pump priming (you need to make 100% sure, instead of "pretty sure") and if your 100% sure you do have spark, your next test should be to check the fuel pressure at the injector rail. There is a port built into the fuel rail for this, and the gauge can (usually) be borrowed for free from your local auto parts retailer. If your fuel rail IS pressurized during the 2 second prime at key on your next test will be to put a "Noid light" on each injector bank (driver's and passenger's sides) to check for injector pulse. As to the oil pressure switch, if your using a modern digital meter set to a "high ohms" position, you could be getting a false reading if it's got the usual oil mist funk on and around it's connector that most do (You DO have it's harness connector unplugged while attempting to measure it, yes?) , check the reading instead on a "low ohms" setting (2K ohms or less). Last troubleshooting thought; have you tried disconnecting the rubber air duct bellow at the throttle body and shoot a bit of starting fluid in there, quickly put the bellow back on and see if it'll run for a second or two on the starting fluid?

PS, jumping that switch will cause the pump to run continuously, even with the key off, as per this handy wiring diagram (you'll see that the orange wire receives constant 12V power from "inline fuse 3") so this is not a good idea;

 

Thank you for your help OrangeBird,

I bought a fuel pressure gauge (Canadian parts stores don't seem to lend tools) and confirmed I had 42 PSI at prime and at crank, and about 30 PSI after 30 minutes of sitting. I was about to order a noid light to test the injectors, but something wasn't sitting right with me and I decided to throw a little money at tune-up parts, since I have never replaced any in the 40,000 km and 5 years I have owned the car, I decided it wouldn't be a waste of money to replace dist. cap and rotor and ignition control module. While I was in there I cleaned up the distributor metal parts a little too. It seems to have fixed the problem. Really did not want to buy a NOID light because this is my only fuel injected car and I am probably planning on selling it... it has been very reliable but just too many electronic parts for me to enjoy repairing when I do have to repair.