24 Valve Cummins Turbo Diesel

Improvements and design changes - Page 4 - Fuel System

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FUEL SYSTEM

• Fuel Injectors
• The fuel injectors are located under the cylinder head cover between the rocker levers (Fig 16), and are secured with a hold-down clamp, cap screw, and shoulder bolt. The shoulder bolt should not be loosened when an injector is removed.

• The fuel injectors operate at 4500 psi pop-off pressure, which is a significant increase over the 3600 psi pop-off of 12 valve engine injectors.
• Fuel is routed through the high pressure fuel line, inside the head, and through connector tubes to the sides of the injectors.
• A new fuel return rifle is bored into the cylinder head to return excess fuel from the injectors to the fuel tank.
• A new O-ring seal on the injector body (Fig 17) keeps engine oil out of the injector and fuel out of the oil.
• A single 1.5 mm copper gasket is used between the injector and head. The copper gasket should be replaced each time an injector is removed and replaced.

• The 24 valve injectors are not serviceable and are not interchangeable with other injectors.
• Centered injection (Fig 18) is used to produce a more even fuel pattern on the top of the piston. This helps equalize the temperature on the piston rings, reduces oil consumption, reduces nitrogen oxide emissions, and permits elimination of the catalytic converter and EGR to meet emissions standards.

• Fuel Injection Pump
• The VP44 Bosch Electronic injection pump (Fig 19) replaces the P7100 inline pump.

• Pump Drive
• As before, a gear train drives the injection pump at 1/2 engine speed.
• The pump is mounted in a fixed position through an offset key (Fig 20). The key is numbered and must match the three-digit number on each pump. Previous injector pump keys, when used, were not specific.

• An arrow stamped into the top of the key must face the pump. A DTC may be set if the key is installed backwards.
• When installing a pump, always have the key at the 12:00 position to prevent the key from falling into the gear train (Fig 21).

• There are no adjustments to make to the pump drive (i.e. no timing adjustment).
• The injector pump is not serviceable, it must be completely replaced as an assembly.
• The injector pump is a high pressure radial piston design and uses two solenoids to determine the timing and amount of fuel that is injected.