How a Fuel Pump Relay Works

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As the owner of a vehicle operating with a gas engine, you may wonder what service the engine's fuel pump relay provides. Here is a brief description of the way this pump relay works to deliver fuel to the vehicle's engine before the engine is actually running

How the Pump Relay Works

A man works on an engine.

Without this relay, the engine would not receive fuel while it is starting. Why? The pump that delivers fuel to the engine while the engine is running requires electricity in order to operate. This electricity is provided through an oil pressure device in the engine. Until oil pressure is created and in turn provides electricity to run the fuel pump, the pump cannot provide fuel to the car's engine. This brief period of time before the engine begins running is when the fuel pump relay is activated by the vehicle's computer

How You Can Tell If the Pump Relay Is Working

As the vehicle's ignition is turned on, the pump relay produces a humming noise. If this sound is not audible, it is an indication that the pump relay may not be functioning as it should.

How the Pump Relay's Components Work

An engine.

When the vehicle's ignition is initiated, the vehicle computer activates the fuel pump relay to pressurize fuel for starting engine. When the engine produces oil pressure the oil pressure switch takes over the task of supplying electrical activation of fuel pump relay and the computer drops out of the task. If the engine does not produce oil pressure in a set number of seconds, the computer shuts off fuel pump and engine stops.