Check engine light staying on. Code31&41

The fuel pump relay on 90s pickups are located UNDER the dash ABOVE the ecu or computer. It's a black relay usualy with a little metal bracket attached to it. You have to take out the kick panel on the passenger side of coarse the glove box has to come out and you should be able to see it tucked up in there above the computer and is held in by 1ea 10mm bolt. If you disconnect and get it off give it a little shake. If it sounds like a baby rattle it's most likely shot and is probably full of rust and broken bits and peices. It's worth buying a new one as its probably the original one that came off the line. I just bought one from oriellys last week was $50 but dont try to stick other relays you might have on hand. I tried and got curious and all off a sudden my truck wouldn't start at all. Went back and forth for a few weeks before I realized the spare fp relay I tried to put it blew the fuse to the fuel injection or the 15amp efi fuse under the hood. Good luck hope this helps.