I am in a 91 Trans AM TPI 305 700R4. I need some serious help. If it is fairly cold outside, say like 50 degrees, when i turn my key onto run, i can not hear my fuel pump engage. when i try to start it, it never starts. When it is warm outside, like 80 degrees, my fuel pump always engages at the run position and always starts my car. I have replaced the fuel pump twice and they both tested good. I have replaced the fuel pump relay. I wouldnt think it would be a fuse. So i was wondering what else it could be. Maybe the oil pressure switch? How hard is it to replace one of those? Please help. Thank you.

 

also, if the oil pressure switch is bad, will that keep your fuel pump from coming on in the run position?

 

Im not sure but i think the Oil pressure switch does cause your fuel pump to cut out if the Oil pressure doesnt work properly... If im worng guys correct me LOL

 

thank you ram air. can anyone else help? i think he is right. also what do i need to change it out.

 

The oil pressure switch keeps the fuel pump on if the fuel pump relay dies. It won't shut off the engine if the oil pump drops (unless the fuel pump relay is also dead, of course).

 

so, are you saying it can't be the oil pressure switch/sender unit? I just want to know why my fuel pump will only come on when it is hot outside but when it is cold my fuel pump gets no power.

 

also, my fuel pump fuse can not be blown since it starts some of the time, right? what else could be preventing this piece from starting?

 

long story short:
i built a new motor.
The oil pressure was low due to galley plugs missing. i fixed it and it now has great pressure. I only ran the motor for the cam breakin and a short drive without the galley plugs. After I fixed it....I took the car for a ride. It got about a mile from the house..and died. When i turn the key on, the fuel pump doewsn't prime or come on. I am worried I spun a bearing and have no oil pressure now, even though I fixex that galley plug problem and that's why my pump won't come on. Could this be accurate, or ois it just the fuel system (i hope)?