Fixing a fuel delivery issue on your engine? This 66-page Yanmar YPD-MP2, YPD-MP4 service manual PDF (OEM #M9961-03E070) breaks down the complete fuel injection equipment system. You get step-by-step teardown instructions for the hydraulic head and mechanical governor, exploded views of the entire MP pump, and a dedicated troubleshooting guide for major faults. Open to detailed bottom clearance adjustments and complete torque tables for reassembly. Verify the wear limit for the inner and outer rotor stays under 0.1mm, and torque the delivery holder to exactly 40-45 N-m before testing the nozzle opening pressure. Stop throwing parts at a misfiring machine. Download this bookmarked file, jump straight to the exact injection timing numbers, and get your pump working perfectly.
What's Inside This Yanmar YPD Series Manual
| System | Pages | Key Topics |
|---|---|---|
| For Safe Servicing | 6-8 | Warning Symbols, Safety Precautions |
| General Information | 9-26 | Outline of Mp Pump, Specifications, Outline of Fuel Injection Pump, Construction of MP-Pump (Fuel Injection Part, Governor Part, Delivery Part) |
| Disassembly, Reassembly and Inspection | 27-46 | Disassembly (Separating the Pump Body From the Governor Body, Separating the Governor Weight Cmp, Disassembling the Hydraulic Head, Separating Hydraulic Head Cmp, Separating the Cam Shaft, Disassembling the Hydraulic Head Cmp) |
| Adjustment of Fuel Injection Pump and Governor | 47-53 | Preparations, Bottom Clearance Adjustment (Bottom Clearance Adjusting Value and Cam Classification) |
| Fuel Injection Nozzle | 54-59 | 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 |
| Tightening Torques for Main Bolts and Nuts | 63-64 | Pump Part, Mechanical Governor Part |
| Tools | 65-66 | Nozzle Plate, Bottom Clearance Gauge, Plunger Sp Seat Extractor |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Pipe joint bolt, fuel inlet torque | 25-29 N-m | p. 63 |
| Plug, barrel torque | 50-55 N-m | p. 63 |
| Feed pump assembly replacement interval | 10,000 hours | p. 23 |
| Wear limit for pump case, pump cover, inner rotor, outer rotor | 0.1mm | p. 24 |
| Delivery holder torque | 40-45 N-m | p. 42 |
| Molded ring replacement | replace | p. 24 |
| Seal washer replacement | replace | p. 24 |
| Governor case packing (GRC) reusability | not reusable | p. 45 |
| Trochoid pump replacement interval | 10,000 hours | p. 23 |
| Wear limit for shaft and oil seal moving area | 0.05mm in depth | p. 24 |
| Tension lever side clearance | 0.3 to 0.6 mm | p. 44 |
| Fixing bolt, tension lever hook torque | 6-8 N-m | p. 64 |
Yanmar YPD Series Common Problems This Manual Covers
Yanmar YPD-MP2 fuel injection pump engine will not start or is extremely hard to start. p. 60
Inspect the feed pump delivery pressure using a gauge. If it drops below the standard 0.4-0.5 MPa, replace the feed pump assembly. Bleed all air from the fuel lines. Review the engine won't start procedures on page 60 for additional fuel delivery checks.
Manual Section: TroubleshootingEngine experiences rough idling, hunting, or completely unstable running speed at low RPM. p. 44
Remove the governor cover and measure the tension lever side clearance. Adjust the linkage to maintain 0.3 to 0.6 mm clearance as detailed on page 44. Inspect the control rack for binding. Torque the minimum idling speed setting bolt to 8-10 N-m.
Manual Section: Disassembly, Reassembly and InspectionFuel leaking from the injection pump body, hydraulic head, or shaft seal area. p. 39
Clean the pump exterior and locate the exact leak source. Replace all worn O-rings and packing. When reassembling the unit, tighten the hydraulic head CMP fastening bolts to exactly 18-22 N-m as specified on page 39. Verify internal pump case wear remains under the 0.1mm limit.
Manual Section: Disassembly, Reassembly and InspectionFrequently Asked Questions
What are some of the tightening torques for the YANMAR YPD-MP2 and YPD-MP4 fuel injection pump parts?
For the YPD-MP2, the pipe joint bolt for the fuel inlet should be tightened to 25-29 N-m, and the plug for the barrel to 30-35 N-m. For the YPD-MP4, the timer holder should be tightened to 40-45 N-m.
What are the replacement specifications for feed pump assembly?
The feed pump assembly should be replaced after 10,000 hours of use as a standard. Additionally, if wear on the face contacting the pump case, pump cover, inner rotor, and outer rotor exceeds 0.1mm, or if wear on the shaft and oil seal moving area exceeds 0.05mm in depth, the entire feed pump assembly should be replaced.
What is the standard fuel injection nozzle opening pressure for hole type nozzles?
The standard fuel injection nozzle opening pressure for hole type nozzles is either 19.6 - 20.6 MPa (200 – 210 kgf/cm²) or 21.6 – 22.6 MPa (220 – 230 kgf/cm²), depending on engine specifications. Adjusting the shims by 0.1 mm will change the injection starting pressure by approximately 2 MPa (20 kgf/cm²).
What is the recommended bottom clearance (dimension A) for the plunger in the YPD-MP2 fuel injection pump at a cam speed of 1.1 m/s?
For the YPD-MP2 fuel injection pump at a cam speed of 1.1 m/s, the recommended plunger bottom clearance (dimension A) is 25.5±0.05 mm. This clearance is adjusted by shims to set the fuel injection timing.
What is the tightening torque for the hydraulic head CMP fastening bolts?
The hydraulic head CMP fastening bolts should be tightened to a torque of 18-22 N-m. It is important to tighten these bolts evenly in diagonal order.
How will I receive this Service Manual?
Immediate download of the complete 66-page searchable Service Manual. Access it on any device, from a laptop at your desk to a phone in the field.
Is this Yanmar YPD-MP2 & variants Service Manual printable?
Absolutely. No DRM or copy protection. Print the whole manual or just the pages you need. Any home or office printer works.
Document Quality
This document is a scanned PDF with an optical character recognition (OCR) layer, allowing you to search and copy the full text. The text throughout the manual is crisp and consistently easy to read. Diagrams and illustrations are a mix of clear raster images and photos, with labels generally readable, though some fine details may show slight pixelation when zoomed in. Pages are mostly clean, with only a few minor, faint handwritten marks on pages 8, 14, 27, 28, and 50. There are no notable blank or filler pages in the document.
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