I'm doing a 96LT1 (94PCM) Swap into a 89GTA.. former 305tpi.

I'm into fuel pump relay wiring. They 89 shows a Tan-White wire going into the fuel pump (turn on) but is spliced to the MAF relay, and the Oil pressure Sens.. as well as the PCM.. I am confused with its operation.. I assume I will reuse my 89 fuel pump relay.. as I don't have fuse box to put the 96 one in.. The way I finally wired it up is to forget about the MAF relay.. (not in 96), and forget that it ever went to oil press sens.. and assume the pcm will tell the pump when to turn on.. Am I correct??

thanks

 

Sounds like what you did should work.

 

we only spent an hour and a half on that .. couldn't figure out why it was going through the oil pres sens.. we figured the computer must turn on the pump for a period of time say 5sec.. then if there is oil press by then, it will keep pumping.. we went with that notion anyway and assumed the lt1 tells the relay when to turn on forever..

 

Thats pretty much exactly how it works, except I don't believe the computer reads the oil pressure. What it does is when you first turn the key to Run, the computer turns the fuel pump on for 2 seconds to prime the system. After 2 seconds, the pump shuts off it the car isn't started. If it is, the computer keeps the relay closed, leaving the pump on.

 

I think the only reason the computer would read the oil pressure as a backup to the FP relay. Once the computer sees oil pressure due to the starter, it turns the fuel pump on.

 

I just checked, the PCM does NOT read oil pressure. The only reason for the pressure sender is for the dash guage. The fuel pump turns on no matter what when the key is first turned to on, then it remains on when it is started.

 

that's the conclusion we came to. COmputer turns on the pump for x sec, then when there is oil pressure the oil press switch closes and provides 12v on same wire. IE if there was no oil pressure after x sec. no more fuel because oil pressure switch would be open..

Would be a safety thing too. if you were upsidedown.. heaven forbid. you would have no oil pressure and the pump would shut off.

 

That makes sense.

 

I'm not sure on which years this is, but the oil pressure switch is used as a backup for the fuel pump relay on newer cars. I'm not sure if the LT1's are included on this though.