'89 S15 fuel problem

I have a 1989 S15 blowing the ECMB fuse if the fuel pump relay is plugged in. I tried unplugging the connector to the fuel pump and sensor at the tank but the fuse still blows. I Looked at the rough diagrams in Haynes book and thought my problem could also be the oil pressure switch. Does anyone know where the oil pressure switch is? My Haynes doesn't show location and I don't have a shop manual. Is it driver side or passenger? Front or back of block? I assume is will be low on block, probably just above the oil pan lip.

What engine do you have?

Sorry! My bad!! 2.8L V6 5-speed manual with TBFI.

Sender is in the oil filter adapter. Several different possibilities for the part, best to bring the old one to the parts store and match it up.