This supplemental harness kit is required when installing Edelbrock return-style fuel kit #3604 or universal sump fuel kit #3605, #3607 and #36052 with E-Street 1 EFI systems. This harness kit is included in the complete E-Street 1 EFI system with sump fuel kit #3606. Includes fuel pump relay harness and a fuel sump adapter harness. Failure to use this harness will cause damage to the fuel pump driver in the ECU.