YANMAR MP Series Service Manual

YANMAR MP Series Service Manual
YANMAR MP Series Repair Manual

Yanmar considers safety of great importance and recommends that anyone that comes into close contact with its products, such as those that install, operate, maintain or service Yanmar products, exercise common sense and comply with the safety information in this manual and on the safety labels. Keep the labels from becoming dirty or torn and replace them if they are lost or damaged. Also, if you need to replace a part that has a label attached to it, make sure you order the new part and label at the same time.

This manual describes the features, service, adjustment and troubleshooting procedures of the Yanmar MP2 and MP4 fuel injection pump models used on TNV Direct Injection (Dl) engines. The fuel injection pump is an essential component of the diesel engine and is designed to respond to engine load.

To provide proper engine performance, the components of the fuel injection system are manufactured to very close tolerances. The fuel injection pump is assembled by Yanmar in a special clean air facility, to ensure all parts are completely clean during assembly. It is highly important that when servicing the fuel injection pump to keep the workplace clean. Any type of debris, dust or rust ingested into the pump, may damage the pump and cause faulty operation.

Yanmar products are continuously undergoing improvement. Contact your fuel injection equipment central distributor for service manual updates and current service bulletin information.

The MP fuel injection pump was developed for use on Yanmar Direct Injection (Dl) diesel engines to comply with new exhaust gas emission regulations. The MP fuel injection pump is a mono-plunger fuel pump that utilizes a distribution shaft to deliver equal amounts of fuel to each cylinder.

Fuel Injection Pump Nameplate
The fuel injection pump nameplate is located on the outside of the aluminum pump body. The fuel injection pump eleven digit part number (Figure 3-1, (1)), identification number (Figure 3-1, (2)) and manufacture date code (Figure 3-1, (3)) are located on the name plate. The information on the fuel injection pump nameplate is required for calibration and service parts information.

YANMAR MP Series Service Repair Manual
This section of the Service Manual describes the operation of the governor, followed by the procedures necessary for disassembly, inspection and reassembly. Diesel engines are used in a wide range of loads and speeds. The governor plays an important role in the operation of the engine by quickly adjusting the position of the control rack to control the amount of fuel injected, according to changes in engine speed. The governor also prevents engine over speeding and provides for the engine stop function.

Governor Operation
The operation of the governor is a precise balancing act between the governor spring force and the governor weight assembly. The governor spring (Figure 4-2, (12)) is connected between the control lever shaft (Figure 4-2, (9)) and governor tension lever (Figure 4-2, (26)) which forces the governor link (Figure 4-2, (28)) to move the control rack.

As the fuel injection pump camshaft begins to rotate, centrifugal force causes the governor weights (Figure 4-2, (33)) to open pushing the governor sleeve (Figure 4-2, (35)) against the governor lever assembly (Figure 4-2, (25)), opposing the force of the governor spring.

At any set control lever position, an increase of load on the engine will try to slow the engine down, decreasing the centrifugal force from the governor weights which allows the governor spring tension to move the control rack (Figure 4-1,(3)) toward the full fuel volume position (Figure 4-1, (2)). If the load decreases, the engine will speed up, increasing the centrifugal force from the governor weights. This pushes the sleeve, moving the governor lever assembly toward the fuel stop position and decreasing the fuel injection volume (Figure 4-1, (1)). This balancing act occurs continuously, keeping the engine RPM at the desired speed setting.