When ting to start my car the engine turns over just fine but doesn't start untill the oil pressure comes up which can take some time. I have replaced the oil pressure sending unit and still no change. Could this be a worn out oil pump??? If so can I change it with out pulling the engine out???

thanks.
1989 formula 305 tbi

 

I'd say your fuel/air and ignition systems are much more suspect than the oil pump or pressure sending unit. The pressure on either of my vehicles comes on up after the engine starts, I think. Is it cranking fast enough? It's also possible your starter is cranking it too slow (not creating enough torque) for the engine to fire up properly. If it were my car, the first things I would check are the fuel pressure, ignition coil and the idle air control circuit. Anyone else? If the oil pressure builds up to a certain point as you crank it, I'm certain it is not defective as that is what it should do with continual cranking.

 

your fuel pump relay is shot. There is a bypass that will start the pump when your oil pressure gets high enough (pressure switch usually near oil pressure sending unit). That circuit was made just for fuel pump relay failure.

 

Good call, man! I'd say FastB is right, and I'm also curious about this because mine's hard to start from time to time. Where is the fuel pump relay on these things?

 

I've replaced the fuel relay switch and that was not it so Ill try the wireing harness that leads to it. It looke a little rough.

 

Are you guys letting the fuel pump prime?

If I jump on the key from off to crank, my motor will spin for a while before starting.

If I put the key from off to on, aka "test lights" where all the dash lights come on, then I wait 2-3 seconds until the fuel pump stops priming, then I turn the key to crank, it starts right up- maybe with 1/2 to 1 turn of the starter.

Try that first... unless of course you were doing that to begin with!


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards

 

I tred doing that frist I disconnected the fuel line and there is no fuel until the car cranks for 10-15 seconds.