Mechanics

Fuel Pump Replacement

Step 17 - Next, match the failed pump to the replacement pump, make sure all electrical and fuel line connections are the same. Clean mounting surfaces using a shop towel and carburetor cleaner. Gently lower the replacement pump into the fuel tank taking note on fuel level sender orientation.


Installing New Fuel Pump

Step 18 - Once the pump has been lowered into position press the pump into place. Use any new O ring seals or gaskets provided with the replacement pump.


New Fuel Pump Installed

Step 19 - After the fuel pump is securely in place, reinstall pump plate mounting bolts.


Reinstalling Pump Plate Mounting Bolts

Step 20 - Then, tighten the fuel pump mounting bolts using a star pattern to ensure a proper seal to the fuel tank.


Tighten Fuel Pump Mounting Bolts

After completing these steps, reverse the order to reinstall the tank back into the vehicle. It's best if a new fuel filter is installed at the time of the new fuel pump assembly. Add gas to the fuel tank before turning the ignition key, this will lubricate the pump.


Helpful Information

Some manufacturers provide an access door to service the fuel pump, be sure to research this information before beginning. To test for a fuel pump failure a fuel system pressure test must be performed. Sometimes the the driveshaft must be removed along with the fuel tank.

The automotive engine is designed to operate on a specific fuel system pressure which is vital to engine performance. To maintain a constant pressure, the fuel pump is located in the fuel tank and is comprised of an electric motor coupled to a small internal vein style pump. Fuel pumps have a pressure relief valve that allows fuel to bypass while recalculating inside the fuel tank. Direct injection fuel pumps utilize an internal pressure regulator, while having only one liquid fuel line routed to the engine as opposed to two, (pressure and return lines.)

When the ignition key is turned the fuel pump relay engages while supplying electrical power to the pump. This relay is controlled by the main computer which must detect engine rotation before signaling the relay. When servicing a truck fuel pump there is the option to remove the bed to access the assembly.


Best Practices

  • Replace the fuel filter when replacing the pump, debris can be dislodged and enter the fuel filter during a pump failure.
  • Have a fire extinguisher available.
  • Inspect fuel pump electrical connector for burns or heated spots and replace if damaged. A burned connector can cause the pump to intermittently fail.
  • The fuel pump is controlled by a relay, this relay should be tested to ensure proper operation.
  • Do not remove tank unless empty or close to empty, a full gas tank is heavy and can cause injury.

AUTHOR


Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2013-11-11)