Fuel Pumps & Fuel Injection Repairs
The electric fuel pump is the heart of every electronic fuel injection system. Let's review the basics of this critical fuel injection part.
Usually located inside or near the fuel tank, the fuel pump's job is twofold:
1) To push fuel from the tank to the injectors, and
2) To create sufficient pressure so the injectors will deliver the correct amount of fuel under all operating conditions.
The pressure developed by the pump, as well as the volume of fuel it flows, must both meet the vehicle manufacturers' requirements or engine performance, economy and emissions will suffer.
The amount of fuel pressure required for a given application will vary depending on the type of injection system (L-Jetronic, CIS, Motronic, etc.), the flow characteristics of the injectors and the engine's fuel requirements.
For example, certain Audi models with Bosch Motronic require 55 to 61 psi (3.8 to 4.2 BAR) of static pressure measured with the engine off. By comparison, a BMW may require 43 psi (3.0 BAR) on some models or 48 psi (3.3 BAR) on others. The differences may not seem like much, but a few pounds of fuel pressure can have a significant impact on engine performance and emissions.
A Few Important Things to Remember
Heed the following repair tips when installing a new fuel pump to avoid problems:
Tip #1: Whether a fuel pump is mounted inside a fuel tank or externally, the inside of the tank should always be inspected and cleaned if rust or debris is found in the pump or filter. Replacing a pump without cleaning a dirty tank will doom the new pump to premature failure.
Tip #2: If you're replacing an in-tank fuel pump, always disconnect the battery to prevent any unwanted sparks. Then drain the tank before removing the tank straps and opening the pump's retaining collar. Keep all flames and sparks away!
Tip #3: When installing the new fuel pump, always replace the filter screen and use a new O-ring or gasket for the sealing collar.
Tip #4: Do not "test" a new pump before it has been installed by jumping it. Running a pump in a dry condition with no fuel to lubricate it risks damaging it. Do not run the pump until fuel has been added to the tank. Also, replace any braided or rubber fuel lines that are flaking or cracked with the correct type of EFI hose.
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Usually located inside or near the fuel tank, the fuel pump's job is twofold:
1) To push fuel from the tank to the injectors, and
2) To create sufficient pressure so the injectors will deliver the correct amount of fuel under all operating conditions.
The pressure developed by the pump, as well as the volume of fuel it flows, must both meet the vehicle manufacturers' requirements or engine performance, economy and emissions will suffer.
The amount of fuel pressure required for a given application will vary depending on the type of injection system (L-Jetronic, CIS, Motronic, etc.), the flow characteristics of the injectors and the engine's fuel requirements.
For example, certain Audi models with Bosch Motronic require 55 to 61 psi (3.8 to 4.2 BAR) of static pressure measured with the engine off. By comparison, a BMW may require 43 psi (3.0 BAR) on some models or 48 psi (3.3 BAR) on others. The differences may not seem like much, but a few pounds of fuel pressure can have a significant impact on engine performance and emissions.
A Few Important Things to Remember
Heed the following repair tips when installing a new fuel pump to avoid problems:
Tip #1: Whether a fuel pump is mounted inside a fuel tank or externally, the inside of the tank should always be inspected and cleaned if rust or debris is found in the pump or filter. Replacing a pump without cleaning a dirty tank will doom the new pump to premature failure.
Tip #2: If you're replacing an in-tank fuel pump, always disconnect the battery to prevent any unwanted sparks. Then drain the tank before removing the tank straps and opening the pump's retaining collar. Keep all flames and sparks away!
Tip #3: When installing the new fuel pump, always replace the filter screen and use a new O-ring or gasket for the sealing collar.
Tip #4: Do not "test" a new pump before it has been installed by jumping it. Running a pump in a dry condition with no fuel to lubricate it risks damaging it. Do not run the pump until fuel has been added to the tank. Also, replace any braided or rubber fuel lines that are flaking or cracked with the correct type of EFI hose.
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