Fuel Pumps
Fuel Pumps

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Failure – Warning Signs – Common Causes – Failure Symptoms

Common Issues – Excessive Heat – Contamination From Dirt and Rust

Fuel Pump Related No Start Problems – What Should You Check

Electric Fuel Pump – How Do They Work – How Can They Fail

Related Problems – Not Always Easy To Solve

Hard Starting Engine – Cold, Hot, Both Or Just After Refueling

Engine Fuel System Testing – Proper Testing With Solutions

Mechanical Pump – Basic Information And Troubleshooting

Fuel Pump Diagnosis Tips from Carter (PDF file – requires Adobe Acrobat Reader to view).


Fuel Pumps

So, There are basically two types:

  • Electric
  • Mechanical

How Do Electric Fuel Pumps Work

So, when the driver turns the ignition key on; the (PCM) energizes a relay that supplies voltage to the pump. As a result, the motor inside the pump starts to spin. Then, runs for a few seconds to build pressure. Consequently, a timer in the (PCM) limits how long the pump will run until the engine starts. Next, fuel is drawn into the pump; through an inlet tube and mesh filter sock. Finally, the fuel then exits the pump, through a one-way check valve.

So, a fuel filter traps any rust; dirt or other solid contaminants; that may have passed through the pump. As a result, preventing such particles from clogging the injectors.

So, the fuel then flows to the supply rail on the engine. And, is routed to the individual injectors. Consequently, a pressure regulator on the rail maintains pressure; and routes excess fuel back to the tank. But, on newer vehicles with return less (EFI) systems; the pressure regulator is located in the tank. Consequently, it is part of the pump module. As a result, there is no return line, from the engine back to the tank.

Fuel pumps are not part of a regular maintenance schedule and only need to be replaced when they fail. Most pumps should last well past 100,000 miles.

Thank You !