Auto Parts: 1988 Chevy S10 4.3L V6 4WD fuel relay, test lead, fuel pump

Question
There are two relays at the same location on the DS fender wall. They look identical, except for the numbers on them, neither of them match the marks on the replacement relay I purchased. How do I know witch one is the fuel relay?

Answer
    GM uses this relay for a number of purposes, so they are probably the same relay.  I would try it in one position, then switch it for the other if that doesn't work.  If it doesn't help in either position, then the relay is not the problem.  Or, you could use a test lead to trace the power back to the fuel pump.  This is not all that easy, so I'd try the other first.