The Bosch VE type single plunger mechanical pump consists of a low-pressure, vane-type fuel pump, a high-pressure distributor-type plunger injection pump, a centrifugal governor, and an injection timing advance mechanism. Pumps are equipped with an electrical fuel shut-off solenoid. See Figure .

As the vane type pump rotor turns, centrifugal force holds the vanes against the walls of the pump's pressure chamber. The offset design of the rotor and pressure chamber squeezes trapped fuel between vanes and forces it out the delivery port.

The amount of fuel injected is controlled by changing the injection cut-off point according to engine speed and load conditions. The cut-off point is controlled by the position of the metering sleeve around the distributor plunger. The sleeve normally covers a relief port in the plunger. Uncovering the port stops injection.

The sleeve position is determined by a centrifugal governor and the accelerator linkage. A large quantity of fuel is supplied during starting, less at idle. No fuel is allowed to pass when the engine exceeds a predetermined maximum RPM.

Fig 1: Injection Pump With Boost Compensator Boost compensator is used on 760 GLE Turbo Diesel.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Fuel Injection Pump

Use the Manual With the Right Hardware

When to See a Mechanic