Let’s take a look at how to replace an old wiring harness, or pigtail, with the new one that is supplied with your new fuel pump module. This replacement is essential, or your new fuel pump may not work properly. 

We always put safety first, so be sure you are wearing safety glasses and gloves. And have a fire extinguisher close by.

Disconnect the negative battery terminal

Start by disconnecting the negative battery terminal. Then disconnect the fuel pump harness from the tank. You’ll need to remove about a foot of the tape and black plastic conduit from the harness. Make sure you are not dealing with the fuel pressure sensor connector.

Match old wiring to new

If the old wiring is not identical to the new wiring, just refer to the diagram that comes with the new wiring. This will help you match the old to the new.  

Cut the wiring

Now you’re ready to start cutting. Cut the first pair of wires about two inches away from the electrical connectors. Then stagger the rest of your cuts by about an inch and a half and strip the wires. Crimp the vehicle wiring to the new wiring harness with the supplied connectors on all wires. Make sure not to trap any insulation between the electrical connector crimp. Next, shrink the insulation with a heat gun to secure the connections.  Of course, be sure to keep this away from any fuel. When the glue begins to come out of the connector, then that means your seals are weather-tight.

Installation

To finish up, install the black plastic conduit and re-tape the wires. And you’re all set. Now you can be confident that the new fuel pump you’re about to install will have a secure connection for the rest of the life of the vehicle.