R2.8 CM2220 R101B Fuel System Section 1 - Installation by Subsystem Page 1-13 Figure 1 - Typical Fuel System Plumbing 1 Fuel supply pump connection 2 Fuel filter with water in fuel (WIF) separator 3 Fuel filter outlet to fuel pump 4 Fuel filter inlet from fuel tank 5 Maximum height from bottom of pickup tube in fuel tank to fuel pump inlet, 1 m [3 ft] 6 Fuel tank 7 Fuel tank vent with recommended check valve and filter; be sure the vent is unobstructed and mounted where it is free from dirt and debris 8 Fuel return to fuel tank drain line 10 Recommended minimum filter elevation 9 Preferred fuel flow routing 11 Fuel return connection on fuel pump.
Fuel Supply (9) and Return (8) lines should be routed away from sources of heat and as directly as possible from the tank (6) to the engine, avoiding both upward and downward loops. Upward loops can act as air traps, which can cause erratic engine operation, and downward loops can act as water traps, which can freeze and block fuel flow. The fuel supply and return lines are to enter the fuel tank at the minimum fuel level. The inside diameter size of both supply and return fuel lines is dependent on the distance from the fuel pump to the tank.
The quantity of fuel flowing to the engine would indicate that a 9.5 mm [0.375 in] inside diameter fuel line size would be adequate for most installations. A 8 mm [0.3125] return line is recommended from the pump back to the fuel tank. The installation of electric priming pumps or lift pumps in the fuel supply line is not recommended. These pumps can add restriction to the system or over-pressurize the engine’s high-pressure common rail (HPCR) fuel pump, resulting in instability and fault codes. Fuel pump fittings and line routing are shown in Figure 2. To buy Cummins Parts and Service Manuals, Training Guides, or Tools go to our website at https://store.cummins.com