All 66 pages of this Yanmar YPD-MP2, YPD-MP4, Yanmar Diesel Engine Model TNV Service Manual PDF (OEM #M9961-03E070) focus on one thing: getting your fuel injection equipment back to factory precision. You get full teardown procedures for the hydraulic head, detailed mechanical governor adjustments, and step-by-step instructions for cold start devices. Open to the fuel injection nozzle section to find exact opening pressures, spray testing methods, and a complete troubleshooting chart for major pump faults. Torque the trochoid pump bolts to 8-10 N-m and verify your feed pump assembly wear limit has not exceeded 0.1mm before reassembling the case. Stop wasting time diagnosing fuel starvation issues. Grab this bookmarked download, jump straight to the clearance specs, and get that engine firing right.
What's Inside This Yanmar YPD-MP 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 the 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 |
|---|---|---|
| Feed pump assembly replacement interval | 10,000 hours | p. 23 |
| Feed pump assembly wear limit (pump case, pump cover, inner rotor, outer rotor) | 0.1mm | p. 24 |
| Molded ring replacement instruction | just replace | p. 24 |
| Seal washer replacement instruction | just replace | p. 24 |
| Fuel filter element action | Disassemble and clean, or replace element | p. 60 |
| Governor case packing reusability | not reusable | p. 45 |
| Hydraulic head packing replacement instruction | replace the head packing with new one | p. 39 |
| Electromagnetic feed pump action | Replace | p. 60 |
| Trochoid pump replacement interval | 10,000 hours | p. 23 |
| Trochoid pump wear limit (pump case, pump cover, inner rotor, outer rotor) | 0.1mm | p. 24 |
| Tension lever side clearance | 0.3 to 0.6 mm | p. 44 |
| Bolt, governor lever shaft torque | 8-10 N-m | p. 45 |
Yanmar YPD-MP Series Common Problems This Manual Covers
Yanmar YPD-MP2 diesel engine cranks but has no fuel delivery and will not start. p. 60
Inspect the fuel lines and bleed air from the system. Test the feed pump delivery pressure. If pressure drops below the standard 0.4-0.5 MPa, check page 23 to see if the trochoid pump has reached its 10,000 hours replacement interval. Replace the entire assembly if worn.
Manual Section: TroubleshootingBinding accelerator rods or internal governor wear with rough idle and unstable running. p. 44
Remove the governor cover and inspect the tension lever. Measure the tension lever side clearance as shown on page 44. Adjust the clearance to fall between 0.3 to 0.6 mm. Torque the governor lever shaft bolt to 8-10 N-m to prevent future binding.
Manual Section: Disassembly, Reassembly and InspectionUneven fuel delivery or retarded injection timing with heavy black smoke and lack of power. p. 58
Remove the fuel injection nozzles and test them on a pop tester as outlined on page 58. Verify the opening pressure reaches 19.6 - 20.6 MPa across all cylinders. Clean the nozzle plates and replace any tips failing the pressure test before reinstalling into the engine block.
Manual Section: Fuel Injection NozzleDamaged molded rings or worn shaft contact area with heavy fuel leaks from the pump body. p. 39
Disassemble the pump body and inspect the shaft seal contact area. Discard the old seals and replace the hydraulic head packing with a new one as instructed on page 39. Install a new Hardness 90 O-ring to prevent future leaks around the shaft housing.
Manual Section: Disassembly, Reassembly and InspectionFrequently Asked Questions
How do I adjust the Yanmar YPD-MP2 / YPD-MP4 injection pump after reassembly?
After reassembly, the fuel injection pump must be readjusted using a special pump tester, especially if major parts like the plunger assembly, roller guide assembly, or fuel camshaft have been replaced. This process involves adjusting the bottom clearance (fuel injection timing) and other governor settings to ensure proper operation. Refer to page 47 for detailed adjustment procedures.
What are the tightening torques for the main bolts and nuts of the Yanmar MP2 / MP4 fuel injection pump?
The tightening torques for various pump parts vary; for example, the pipe joint bolt (fuel inlet) is 25-29 N-m for MP4 and M12x1.25, while the plug (barrel) is 50-55 N-m for MP4 and 30-35 N-m for MP2. The delivery holder requires 40-45 N-m for MP4 and 28-32 N-m for MP2. A comprehensive list of torques for pump parts can be found on page 63.
How do I troubleshoot low fuel delivery pressure on a Yanmar MP2 / MP4 pump?
Low fuel delivery pressure can be caused by an insufficient fuel supply from the feed pump, which may require repair or replacement of the feed pump. The feed pump failure causes the delivery pressure and volume to drop, potentially shortening the service life of the fuel injection pump. Refer to page 60 for troubleshooting details.
How do I bleed air from a Yanmar MP2 / MP4 injection system?
To bleed air from the fuel injection system, you need to complete the fuel oil piping and then operate the pump tester to purge the line of air. If air sucking is identified as a fault, the recommended remedy is to bleed air from the system. This procedure is part of the preparations for pump adjustment, as detailed on page 48.
What are the replacement specifications for the F.O. feed pump assembly?
The F.O. feed pump assembly should be replaced after 10,000 hours of use as a standard maintenance procedure. This is crucial because a feed pump failure can lead to a drop in delivery pressure and volume, which shortens the service life of the fuel injection pump. Refer to page 23 for more details.
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 & YPD-MP4 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 quality is crisp and easy to read throughout. Diagrams and illustrations are raster images, but they are generally clear, and all labels are readable. The pages are clean, free from scan artifacts, stains, or skewed content. There are no notable blank or filler pages present.
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