zander lane

So, Ive had this Firebird since my dad gave it to me when I was 16. Ive always been able to figure out a problem, and trust me there is ALOT! But for some reason, the car takes lots of time to crank before it will turn over and start. Ive had shops look at it and people have given me advice from friends etc. I keep getting all different answers.
So what I see and know, is that the fuel system has all been cleaned, and the fuel pump has been replaced. Not a fuel problem, I within the past week replaced the oil pressure sensor, all the spark plugs n wires, as well as the distributor are all new on the car (last 2 years)
The car only seems to start once the oil pressure starts to go up, for the first 15 seconds or so of cranking shows no pressure then the second the pressure shows the car starts. I'm stuck having to think its the oil pump but I can't explain why and I feel like it could be something else. Replacing the oil pump is just not an option RN and for the cost of replacing it and having 88k miles I feel like id be better off to replace the motor in a few years. Do we have any thoughts?

Any help is appreciated!
Thanks,
Zander

P.S. Its a 1989 Pontiac Firebird, with a 5.0 v8 TBI

vinny R

The fuel pump has a relay on the fire wall that is connected to the fuel pump. When you hit the key the relay activates the pump for a few seconds, this primes the system. You should hear the pump running in the tank. The oil pressure switch also run trough the relay. It has to sense oil pressure to turn on the pump. It sounds like the prime system is not working and until the oil pressure comes up then the pump comes on. Try replacing the relay.


The other thing is my car used to do the same thing, cranked a long time before it would fire. I ended up switching the gas I use. I switched to non-ethanol rec 90. Now it fires right up no matter how long it sits. I read somewhere that when our cars were new the computer is programed to straight gas, no added ethanol.

zander lane

So I thought I did already and I did, I replaced that relay a few years ago when I was having fuel issues. I did notice that when I turn the key I don't hear the fuel pump. :/

zander lane

So I thought I did already and I did, I replaced that relay a few years ago when I was having fuel issues. I did notice that when I turn the key I don't hear the fuel pump. :/

Tuned Performance

iTrader: (92)

You might want to check for the 2 sec prime power from the ecm to the relay green/white wire.

GeneralDisorder

iTrader: (1)

If you replaced the relay a few years ago that makes it even more suspect unless you got it from the dealer.

GD

zander lane

GeneralDisorder

iTrader: (1)

Tan and Green wires at what connector?

GD

x55Cam

Zander, take it step-by step. Is there a code being thrown by the ECM (Check Engine Light)? the first thing you should hear when you turn the key to the on position BEFORE cranking, is if you hear the fuel pump go on for about 2 seconds to jump the fuel pressure to operating conditions. Usually around 40 PSI. You may need a fuel gauge to help determine this. If you don't have a gauge and assuming the pressure is there may be tough to trouble shoot. But with a meter , you need to put the blk lead on to a good ground - battery ground for example - and the red lead on the TAN/WHT wire (B2 of ECM). There will be voltage of about 12VDC present to operate the Fuel Pump relay for a bout 2-3 seconds. Hopefully the pressure will be there for the TBI to distribute fuel.

JA411

Fuel pump has a check valve in it to keep pressure to the TBI. If it's bad it takes along time to prime @ 9psi for TBI. Also if the pressure regualtor in TBI unit is bad (leaking pressure back to tank) it will have an extended crank.
JOE

Pro

He has a TBI, its not going to be at 40PSI, maybe 10-15 if its any good.
And the TBIs I have seen in the trucks which is probably near the same design in the camaros/firebirds all drain back to the tank immediately after prime. If he wants to test the check valve hell have to pinch the return line.

x55Cam

ok, I missed that about the TBI - he may have to pinch the return line but a gauge should quickly indicate the pressure before the bleed back.