IRCM is home to the fuel pump relay in a 90 SC as J.D. mentions ...so the question is ..did you replace the IRCM ? ...what relay are you unplugging? the fuel pump uses 2 relays to work ...fuel pump relay and the EEC relay ..the fuel pump relay ....is fed power on a black/yellow wire... from a 30 amp high current fuse ...in the high current fuse box ...and is hot all the time [constant power] ...now to energize the coil part of the fuel pump relay ..ignition switch... is turn on to ...start or run ..this powers the EEC relay ..this in turn sends power ....through the inertia switch [fuel cut off] energizing the coil .....in the fuel pump relay ..there by.. turning the pump on ..now i'm thinking ... you may have a igntion switch problem and should check before buying a new IRCM ..to confirm turn key to off.... and check for voltage.... to the 30 amp EEC relay fuse... in high current fuse box ..... the [G] fuse..with key off.....there should be no power at fuse ..but try turning it on first ..start fuel pump ..then off ..... right next to the EEC relay fuse [G]......in the high current fuse box..... is the fuel pump relay fuse [H] .....and is fed constant power ..make sure it's not shorting to the EEC fuse ..I've seen a melted high current fuse box before ... and can cause weird things to happen ...dave