I am diagnosing a no-fuel delivery problem on a '92 RS tbi 305 (my son's car). I found some good info here this morning on the relay and oil pressure switch.

The other thing I need, is to find out which of the three wires going to the tank should be hot for the fuel pump. Because if I'm getting 12V on the correct wire, then it must be the fuel pump itself... The haynes manual seems to be missing the fuel wiring diagram for the tbi cars.

I know the lines and filter are clear. The car sat for 6 months and the battery was completely dead for most of that time, but I can't figure how that would kill the pump or the wiring.

So, if anyone knows which wire does what back there, let me know.

(oh, and I was referred over here from another board (a v6 board for my '98) by Project, he said to tell you he sent me...)

 

John_D,

Welcome Aboard!

I'm not positive on the '92, but the earlier TBI wiring harness is not that different from the TPI system. You should have power on the tan/white wire at the tank flange/fitting. There should also be a pink wire (gauge) and black wire (ground). You may measure voltage at the pink wire, but it should be lower than 12V.

 

Vader, thanks for the info!! I will try it this weekend.

 

Ok, the wire colors were not quite the same. The description of what I should find on each one, helped a bunch though.

The black wire was a ground, and it was on the passenger side.

The middle wire was the fuel gauge, and it ran around 8 volts.

The wire on the drivers side was the fuel pump, and it would come on 12v for a second or two to prime the line, then go to zero. It was grey.

So it ended up being the fuel pump after all. I tried shooting direct 12v to it off and on, trying to get it to budge, and nothing happened. What a pain to get that thing out of there...

Thanks again for the info!!!

 

John,

Sorry I didn't have the correct wire colors, but at least you were able to diagnose the problem. The fuel pump location seems quite clever, until it has to be changed. I know how you spent your weekend. I trust you had your son involved to "learn".