Have heard one of the coils on the CO relay can get weak over time and not pull in the CO relay contacts hard enough to make good contact. I had something like this on my '85 with the starter coil and ran with the jumper installed for a few years. Then one day I pulled the jumper and found the relay was working fine (and has ever since).

I used a pair of spade lug connectors on the end of a short length of wire in mine (older style connector):


But later replaced the jumper with a switch:


Of course since doing that, have not had a problem with the CO relay or fuel pump.