If you were to put a resistor like this in a live circuit, it will get hot. The same is true for components like connectors, wires or even the pump. This heat can result in melted connectors and wires. So when the harness is first disconnected, look for any discolored plastic or a blue tint on the pins in the connector.
If you see a melted connector, it’s a sign there is too much resistance that should not be present, or it is a sign of a bad connector. One of the most common reasons for a connector to go bad is the retention clips. If a connector does not have good retention and a tight connection, it can lead to resistance heat problems.
Corrosion on terminals has been an issue recently due to the location of the connector on the tank. On many vehicles, the fuel pump connector is located on top of the tank where road de-icing brines can accumulate. These de-icers stick to the vehicle worse than road salt and can re-activate when moisture is present. These chemicals can be vicious, attacking and wicking into connectors and wires. This can cause increased resistance and voltage drops.
If you’re replacing a fuel pump, service the connectors. Clean the connector with an electrical contact cleaner. Remove any seal, clean it and apply a light film of dielectric grease.
Some fuel pump manufacturers include a new pigtail harness for the vehicle to connect the new fuel pump. It is not a conspiracy to reduce the number of parts or make your life difficult. Instead, it means that they have identified a problem application that has a high rate of returns due to the connector on the vehicle not being addressed when the fuel pump is replaced.
This video is sponsored by Carter Engineering.