Car fuel pump relay

How to detect the fuel pump relay failure

You need a test lamp to check the fuel pump relay performance. One of its contacts should be connected to the pin going to the controller, the second to the wire from the main relay. Then you need to switch on the ignition. The absence of light indicates the part failure.

Then you need to close the pins to which the battery is connected and the fuel pump power cable with the help of a jumper. If the pump is activated after you turn on the ignition, the relay is faulty.

Another method is installing a fully operable part instead of the part that is being tested.

You may identify that the fuel pump relay requires to be checked by the following symptoms:

• the fuel pump is constantly operating and does not turn off even at the maximum rpms;
• after you turn on the ignition, there is no sound of the pump working;
• the battery is discharged fast.

Causes of the fuel pump relay failure

Due to prolonged use, the relay contacts wear out, and the return spring loses its tension. Poor contacts connection prevents the electric current free flow, so eventually they burn.

Another frequent cause of the relay failure is a clogged fuel pump that has to operate under increased loads to reach the required output. As a consequence, the voltage level consumed by the pump rises, the load on the relay contacts increases, which over time leads to their burning out. Similar effects may occur due to delayed fuel filter replacement or bad contact in the fuel pump wiring harness.

Depressurization of the relay housing can cause many faults. Ingress of dirt and moisture inside the part may lead to oxidation of contacts, rusting and jamming of the armature, destruction of the coil winding insulating layer and consequently to a short circuit.

A fuse of excessive capacity may cause this component to burn out frequently - even in a vehicle with a clean fuel system and a faultless fuel pump.

Replacement of the fuel pump relay

The part repair is inexpedient, therefore, in case of failure, it is subject to replacement. While installing a new component, even a beginner driver won’t have major difficulties. All you need to do is specify the relay location in your car technical documentation. Most often it is installed under the hood in the relay and fuse mounting box, but can also be located under the dashboard, rear seat, in the luggage compartment behind the rear light or near the glove box lid.

When installing a new part, ensure that its characteristics comply with the vehicle technical requirements. Otherwise, the risk of the relay premature failure and incorrect operation of the entire fuel system increases considerably.