Currently looking to put a holley sniper in the car, is there anyway to change the sending unit to a three prong from a 2 prong? Where can I find a wiring harness or is there a way to retrofit it?

 

What do you need to retrofit? You should be able to use the stock set-up with possibly a higher pressure pump.

 

I’d like to bc change the tank, and would like to keep the same capacity, and only sending units I can find are the ones with the pump and 3 prong switch

 

If you need to replace the tank can you not reuse your current sending unit?

 

you likely won't find the carb'd (no in-tank pump) sending unit new. members here have been modifying the 3-wire fuel pump sending unit to work with a carb'd set up for years.

but if you're changing to fuel injection why would you NOT want an in-tank pump?

 

A lot of the aftermarket EFI systems say not to use the stock style in-tank pump because they ground the fuel pump wiring for the fuel pump control and the stock sending unit has a ground tied to it directly. The fix is easy though. Use the signal from the aftermarket harness to control the stock fuel pump relay and leave the stock oil pressure switch in place. Makes it simple because the only change needed to the factory fuel pump wiring is to control the factory fuel pump relay via the fuel pump control wiring on the aftermarket EFI which is 2 connections underhood.

 

I wired my Fitech to the fuel pump circuit exactly as Fast stated.

if he has an '84 VIN H there may be no existing fuel pump relay or circuit, then you can either install a relay or re-wire the 3-wire sender for a separate ground to the pump.

otherwise the sender unit comes wired with the pump and the level sensor sharing a ground.