Part of the Yanmar Repair Manuals.
An injection pump rebuild stalls the moment you need a number nobody posts online: the plunger diameter, the delivery valve pressure drop time, the torque on the governor weight nut. This Yanmar service manual (publication M9961-03E080) settles those questions for YPES-ML series fuel injection equipment, whatever engine the pump came off.
Across 65 pages it works through the fuel supply system, then full disassembly, inspection, and reassembly of the injection pump and governor, followed by bench adjustment: injection timing, plunger and delivery valve pressure tests, and injection volume balancing across cylinders. Separate chapters handle the fuel feed pump and the injection nozzles, including washing, inspection, and opening pressure adjustment.
The PDF downloads immediately after purchase, with 61 bookmarks, so you can jump from a sticking plunger straight to the inspection limits and torque figures you need before the pump goes back together.
What's Inside This Manual
| System | Pages | Key Topics |
|---|---|---|
| Introduction | 2 | |
| for Safe Servicing | 6-8 | Warning Symbols, Safety Precautions |
| Fuel Supply System | 9-21 | Fuel Injection Pump Construction, Fuel Injection Pump Specifications, Fuel Injection Pump, Injection Volume Control, Governor Construction |
| Disassembly, Reassembly and Inspection of Governor and Pump | 22-36 | Governor Disassembly, Inspection of Governor, Disassembly of Fuel Injection Pump, Inspection of Fuel Injection Pump, Assembling Governor |
| Adjustment of Fuel Injection Pump and Governor | 37-49 | Preparations, Top Clearance, Of Injection Timing, Plunger Pressure Test, Delivery Valve Pressure Test, Injection Volume (Measuring Injection Volume) |
| Fuel Feed Pump | 50-52 | Fuel Feed Pump Specifications, Disassembly and Reassembly of Fuel Feed Pump, Fuel Feed Pump Inspection |
| Fuel Injection Nozzle | 53-59 | Functioning of Fuel Injection Nozzle, Type/Construction of Fuel Injection Nozzle, Fuel Injection Nozzle Disassembly, Fuel Injection Nozzle Inspection (Washing) |
| Troubleshooting | 60-62 | Troubleshooting of Fuel Injection Pump, Major Faults and Troubleshooting |
| Tools | 63-64 | Pump Mounting Scale, Measuring Device, Plunger Insert, Tappet Holder, Rack Indicator, Plunger Gauge |
| History of Revision | 65 |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Governor weight nut tightening torque | 68.6 - 73.5 N-m (7.0 - 7.5 kg-m) | p. 32 |
| Delivery holder tightening torque | 29.4-34.3 N-m (3.0-3.5 kgf-m) | p. 40 |
| Fuel filter element replacement | Disassemble and clean, or replace element | p. 60 |
| Fuel feed pump discharge volume | 230 cc/min at 1500 cam rpm, discharge pressure of 0.2 kg/cm² | p. 50 |
| Fuel feed pump closed off pressure | 0.3 kg/cm2 or more (at 400 cam rpm) | p. 50 |
| Stop solenoid replacement | Replace | p. 60 |
| Plunger diameter | 6 mm | p. 11 |
| Injection starting pressure (NP-Dnopd nozzle type) | 11.8 – 12.8 Mpa (120.3 – 130.5 kg/cm²) | p. 37 |
| Nozzle opening pressure (NP-Dnopd nozzle type) | 12.3MPa (125.4 kgf/cm2) | p. 54 |
| Injection pipe inner/outer diameter × length | Φ1.8/Φ6.0 × 500 mm | p. 37 |
| Injection pipe minimum bending radius | 25 mm | p. 37 |
