In the last decade, fuel delivery systems have evolved to become a state-of-the-art technology. Changes were made without the service technician having to learn a lot more on how to maintain and service the fuel delivery systems. But one part that has been constantly getting upgraded each and every year is the fuel pump.
A decade ago, the pump was attached to the sending unit and would deliver pressurized fuel to the injector fuel rail, mounted in a steel tank where a bowl was fixed inside the fuel reservoir to prevent fuel starvation upon acceleration/braking or during cornering.
Vehicles are now using plastic fuel tanks and it’s become more difficult to add internal accessories such as a fuel bowl. Now, fuel pumps carry their own bowl and are referred to as fuel modules. These modules incorporate a plastic bowl to ensure adequate fuel pressure and volume in all possible conditions.
Depending on the manufacturer’s requirements, a turbine centrifugal or roller vane pump can be used to accommodate the necessary volume for the engine needs. Mounted in a plastic or aluminum bowl, the pump will stay submerged in fuel regardless of the fuel quantity in the reservoir.
When the fuel reservoir is nearly full, fuel overflows inside the bowl, which keeps the pump submerged. But when the fuel level is low (1/4 or less), the pump is designed with a built-in fuel jet and check valve system that fills the bowl whenever the pump is running. The jet pump helps keep the pump fully submerged in fuel, which maintains pump cooling plus regulates the fuel supply during acceleration and cornering. The fuel module incorporates the same component as a sending unit-mounted pump, fuel level sensor, float, strainer and power leads to the fuel pump. In addition, some newer models also incorporate a built-in pressure regulator and a fuel tank pressure sensor.
Remember that testing the fuel delivery system remains basically the same — pressure, volume, electrical and filter elements need to be thoroughly inspected before proceeding to the replacement of such an assembly.
Here are a few necessary tips when dealing with fuel delivery modules:
1. Fuel pressure and volume readings are a must.
2. Test power and ground to the pump, which, in most cases, will affect volume more than pressure.
3. Fuel filters must be replaced every time a fuel delivery system concern occurs.
4. Do not install a new fuel module if the fuel tank is contaminated (from dirt or rust).
5. Inspect the fuel filler neck and hose that can cause fuel tank contamination.
6. When installing a fuel module, fill the tank at 50% of its capacity with clean filtered fuel.
7. Cycle the ignition switch several times without starting the vehicle to prime the system and prevent fuel pump damage.
Courtesy of Spectra Premium Industries, Inc.
