I have 89 gt 5.0 And my friend I bought it from had installed the ford racing multiport efi wiring harness an it hasn't run since. Has tons of mods an was running before this. 24lb inj, alum heads, headers 76mm T.B, ect. Anyway I noticed there is a fuel pump relay on new harness and the stock is under driver seat. But when you turn key neither work I tested and bypassed the one under seat an pump run? Dont tell me this harness has to be pulled out.
THIS HARNESS IS NOT MENT TO BE A REPLACMENT HARNESS FOR A FOX BODY MUSTANG. IT DOES NOT CONNECT TO THE BODY HARNESS IS ANYWAY, SHAPE, OR FORM. IF YOU HAVE SPARK, AND FUEL INJECTOR PULSE AND YOU ARE SURE ITS FUEL RELATED, RUN A STAND ALONE RELAY FOR THE FUEL PUMP VIA KEY ON, THAT SHOULD HELP. THE OTHER ALTERNATIVE IS PUT THE OLD HARNESS BACK IN.