Fuel Pumps

Over the years, Toyota has used two types of electric fuel pumps on EFI systems. The early Conventional EFI system used an externally mounted in-line pump. These roller cell pumps incorporate an integral pressure pulse damper or silencer designed to smooth out pressure pulses and provide quiet operation.

Later model production engines utilize an intank pump integrated with the fuel sender unit. These turbine pumps operate with less discharge pulsation and run quieter than the in-line variety. In-tank pumps can be serviced by removing the fuel sender unit from the tank. Make sure that the pump coupling hose is in good condition prior to replacing the pump.

Both pumps share many features. They are referred to as wet pumps because the electric motor operates immersed in fuel. Passing fuel through the pump motor aids in cooling and lubrication.

An outlet check valve is incorporated in the discharge outlet to maintain residual or rest pressure when the engine is turned off. This reduces the possibility of vapor-lock and improves starting characteristics. A pressure relief valve is used to prevent over-pressure and potential fuel leakage in the event that pressure or return lines become restricted.

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

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