Hello JCK
A 1960s +4 used to use the mechanical fuel pump on the left side of the engine , so I assume that your electrical one is a later addition.
If you are using a Bendix type pump they are polarity sensitive , one designed for positive earth won't function on negative. The only remedy I know is the replacement option since these units are normally sealed.
The wiring of a 1960s +4 does not have any relays, and only 2 fuses as standard , so check that one not burnt out from your electrical short. if you used a fused feed to the pump.
