Tapping into the injection pump circuit is a good idea...I have a relay sitting on the shelf... A wiring diagram would be real nice but didn't feel like spending $100 to get one...First thought is to tap the injector pump circuit and use it to run a contactor. Unless there is a spare keyed hot in the harness I doubt there is a circuit that can take the additional load directly without blowing fuses. A wiring diagram would be your best friend.