Detroit Diesel Manual (EN)

MBE 4000 SERVICE MANUAL 2.9 FUEL SYSTEM INSPECTION Perform the following steps to inspect the fuel system for damage: To avoid injury from penetrating fluids, do not put your hands in front of fluid under pressure. Fluids under pressure can penetrate skin and clothing. To avoid injury from fire, keep all potential ignition sources away from diesel fuel, open flames, sparks, and electrical resistance heating elements. Do not smoke when refueling. NOTE: For additional safety precautions, refer to the General Information section of the MBE 4000 Service Manual (6SE412). 1. Check fuel delivery lines looking for deformation or bent lines, creating restriction and/or obstruction of the flow. 2.

Check suction lines and connections looking for damage or under torque, allowing air to enter the fuel system. 3. Check the fuel tank installation. Look for bent/blocked lines, and leaks. 4. Check high-pressure lines for leaks. Look for connector nut leaks at the unit pump and at the transfer tube on the cylinder head. In the event of leaks, disassemble and inspect the high-pressure lines/transfer tube. For proper torque specifications, see those listed in Table 2-2. Table 2-2 Torque Specifications for Fuel Line Nuts 5. Perform a fuel pressure test. Refer to section 2.9.1. All information subject to change without notice.

6SE412 0206 Copyright © 2003 DETROIT DIESEL CORPORATION From Bulletin 6-MBE4000-03 2-41 Component Torque Transfer Tube Nut 45 N·m (33 lb·ft) High Pressure Line Nuts 30 N·m (22 lb·ft)

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2.9 FUEL SYSTEM INSPECTION 2.9.1 Performing a Fuel Pressure Test Perform the following steps to conduct a fuel pressure test: 1. Install the pressure gauge on the fuel system. There are two possible setups for this installation. Setup 1 has the gauge installed after the fuel filter. See Figure 2-23. Setup 2 has the gauge installed before the fuel filter. See Figure 2-24. 1. Fitting 4. Fuel Outlet Line 2. Fuel Filter Housing 5. Unit Pump 3. Mechanical Gauge Figure 2-23 Gauge Installation After the Fuel Filter All information subject to change without notice. 2-42 From Bulletin 6-MBE4000-03 6SE412 0206 Copyright © 2003 DETROIT DIESEL CORPORATION

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MBE 4000 SERVICE MANUAL 1. Fuel Pump 4. Fuel Outlet Line 2. Fitting 5. Mechanical Gauge 3. Fuel Filter Housing Figure 2-24 Gauge Installation Before the Fuel Filter NOTE: The fitting applied in both setups is not a special tool and it is not included in the Mercedes-Benz kit or SPX kit. This fitting is a component and it can be ordered from Canton PDC under part number 915039012205. All information subject to change without notice. 6SE412 0206 Copyright © 2003 DETROIT DIESEL CORPORATION From Bulletin 6-MBE4000-03 2-43

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2.9 FUEL SYSTEM INSPECTION To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. Diesel engine exhaust and some of its constituents are known to the State of California to cause cancer, birth defects, and other reproductive harm. Always start and operate an engine in a well ventilated area. If operating an engine in an enclosed area, vent the exhaust to the outside. Do not modify or tamper with the exhaust system or emission control system. 2. Start the engine and warm it up to working temperatures: 80 - 95 C (176 - 203 F). 3. Check the fuel pressure at two points: idle speed and rated speed.

4. Compare the test results with the fuel systems specifications for pressure listed in Table 2-3. If any of the readings are out of spec, follow the proper troubleshooting steps. Table 2-3 Fuel System Specifications for Pressure 2.9.1.1 Fuel Pressure Test Troubleshooting Procedures For results out of specs on the fuel pressure test, check the following appropriate steps: 1. At idle rpm, with fuel pressure lower than 2 bar (29 psi), check the following: Check the pressure valve at the end of the fuel gallery. Look for opening pressure 2 bar (29 psi). Check the fuel pump assembly (bearing and/or driven gear). Check to see if the fuel system is drawing air. 2.

At rated rpm, for fuel pressure lower than 5.5 bar (80 psi), check the following: Check the water separator filter condition. Check for restriction at the check valve on the PLD-MR heat exchange plate. All information subject to change without notice. 2-44 From Bulletin 6-MBE4000-03 6SE412 0206 Copyright © 2003 DETROIT DIESEL CORPORATION Speed Pressure Fuel Pressure Test at idle rpm 2 bar (29 psi) –minimum Fuel Pressure Test at rated rpm 5.5 – 6.5 bar (80 – 95 psi) Maximum difference between fuel filter housing inlet and outlet pressure 0.3 bar (4 psi)

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