Well I have had problems starting my car for some time now. I always thought it was electrical related, but now I think I may have found a revealing symptom. Whenever the car has sat for say, 10+ hrs, it is difficult to start. Once it is started, it can be shut off and restarted no problem for hours. The battery has no drain, because everytime I've checked it it's at ~12.7 V. The oil pressure just sits at 0 until lots of cranking is done. Finally, once the pressure builds up to around 45 (maybe 5 seconds of cranking) it starts right up. The owner before me put in a high pressure oil pump (250 miles on the motor/pump). Any idea why it takes so long for the oil pressure to build?

 

The fuel pump relay is probably bad. It is turned on by the ECM before and during cranking. The oil pressure switch is there as a backup if the relay fails. It takes may revolutions of cranking for it to turn the pump on. The symptoms are as you describe.
Easy check: have someone listen at the tank for the pump to run at key on. It should run for 1.5 seconds.
If it doesn't, check the relay circuit.

 

mine was oil pressure switch, replaced and now pump starts on key, and cranks .

 

87gtaj, I have the exact same problem with my 86 IROC and have not been able to track it down. When I turn the key to "Ign" the pump primes for about a second or two, then stops, try to start it then and it will usually start on the third try...

 

The pump does prime, I can hear it inside the car. I would assume that it's not the pump relay then...or is there another check to make sure?

I'll have to look into the OP switch. Also, I wanted to ask, my pressure is pegged at 60psi when cold until it warms up, then it calms down to about 30-40psi. When I get on the gas, it goes back up to being pegged at 60psi. I don't know what the specs on the pump are, but are these pressures typical of aftermarket high pressure pumps? I always assumed it was because of the pump, but maybe the gauge is just faulty because of the switch? Ideas?

 

I just tried a replacement relay, and the same thing happened. So does it seem logical that it's probably the oil pressure switch that's faulty then? Any ideas on the pressures that I see?

 

i have the exact same problem as you for about the past 3 yrs, change relay and cked pump circuit, still same problem, im also was beginning to think it was the oil switch, iac or tps (cold start and temp sensor was also repalced), only beacuse once the car was started it would idle up and down. now all of as sudden as the weather has started to get colder and im about to put her away for the winter she starts on one crank, so now im completely stumped.

 

Hey GOATS2QUICK, just to clarify, you replaced the switch, which I believe is above the oil filter (pic 1), and not the sender, which I believe is near the dizzy (pic 2)?

 

I got a chance to change the oil pressure switch today (#2 above) and the problem still persists. It seemed as though the car started at a lower oil pressure (which could be a result of the original switch reading high) and the car idles with an oil pressure just under 60 (it used to be past 60), again it goes above 60 when I get on the throttle. So I think my switch was bad, but the car still takes quite a bit of cranking before it'll turn over. Any more ideas on what to check? What else could cause the delay in oil pressure build up? Insufficient starter?

 

Hmm....the fact that you have 60psi suggest you don't have a bad fuel filter. Does it get to 60psi right when you turn on the pump. Also did you say you changed the cold-start switch? Maybe your cold-start injector isn't working? Mine was having that problem after having it on the scanner a few times and making some adjustments i figured out i had a bad ECM. Changed it yesterday and now it starts right up. I would check the pressure first and see how fast it builds to 60psi. If it still doesn't work then i would spray some starting fulid behind the throttle plates. If that works i would look at your cold start injector. Just shooting out some ideas.

 

Thanks for the response, but I'm not sure if you read it right, the pressure I'm talking about is oil pressure, not fuel pressure. I changed out the oil pressure switch by the dizzy (my car has two). Are you referring to fuel pressure?
The car starts every time, it just doesn't start until sufficient oil pressure builds up. My problem is that it takes quite alot of cranking to build the needed oil pressure. Once that pressure is built, it starts right up. I have my cold start injector disconnected because I don't really need it dumping more fuel into a car getting single digit MPG as it is.
When you said yours was having the same problem, exactly what were you referring to - the cranking issue?