Fuel Filters
The importance of fuel filtration cannot be overemphasized with modern fuel systems. The combination of increasingly restrictive emission regulations and more efficient engines requires the fuel system to operate at much higher pressures. Higher pressures can only be achieved using fuel injection components with very close tolerances. These close manufacturing tolerances have significantly reduced capacities for debris and water.
We have found several customers having fuel system issues related to aftermarket fuel filters.
OEM Brand fuel filters have been designed and produced specifically for these applications to protect the engine from debris and water. Always change engine fuel filters at the intervals specified in the fuel system service manual.
Before you start working on the engine, let it sit for 5 minutes to allow the fuel rail pressure to lower. Then, open the first line slowly to ensure the pressure has been relieved. High-pressure fuel is dangerous.
Fuel Return
Excess fuel leaves the HIGH-PRESSURE pump through the overflow port and into the return-to-tank line. The overflow is controlled to a pressure of less than 20 kPa (2.9 psi). It is very important to keep fuel return pressure below 2.9 psi. We don’t recommend any type of valving on the fuel return system.
Exceeding the allowed fuel return line pressure could cause the high pressure pump shaft seal to fail. Failure of the seal will lead to fuel contamination of the lube oil sump which could result in a catastrophic runaway engine situation.