Part of the Yanmar Repair Manuals.
Set an MP pump on the bench with the governor housing off and you are looking at a plunger, a control rack and a governor weight assembly that all have to go back together in one exact order. This Yanmar service manual, publication M9961-03E070, works that order in both directions for the YPD-MP2 and YPD-MP4 series fuel injection pumps, models YPD-3MP2, YPD-4MP2 and YPD-4MP4, fitted to Yanmar TNV diesel engines.
Across 66 pages it covers pump construction and specifications, full disassembly and reassembly of the hydraulic head, camshaft and governor, bottom clearance adjustment for injection timing, and fuel injection nozzle service from washing through pop pressure setting. Symptom-based troubleshooting tables and a tightening torque chart for the pump and mechanical governor close it out.
It is a bookmarked English PDF that reads well on a laptop beside the test stand and prints cleanly for the bench.
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 | Mp Pump, Specifications, Fuel Injection Pump, 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
Engine cranks but will not start
Air sucked in at a loose connection, a clogged filter or pipe, or weak feed pump delivery will stop a TNV engine from lighting off no matter how long you crank. The troubleshooting tables walk the fuel injection pump checks in order so you find the dead component instead of swapping parts.
Manual Section: Troubleshooting p. 60Hunting or unstable idle speed
Governor wear and a sticking control rack show up as an idle that surges and hunts. The adjustment procedures cover no load maximum speed, the fuel limit bolt, torque-rise point and starting injection amount so the governor can be set back to spec on the test stand.
Manual Section: Adjustment of Fuel Injection Pump and Governor p. 47Fuel leaking from the pump body
After long service, fuel weeps past the shaft seal area and the joint faces. Resealing means splitting the pump body from the governor body, and this section shows the sequence; the manual treats molded rings, seal washers and governor case packing as replace-on-disassembly items, not reusable parts.
Manual Section: Disassembly, Reassembly and Inspection p. 27Black smoke or poor nozzle spray
A dribbling or carboned nozzle shows up as smoke and rough combustion before anything else does. The nozzle procedures cover disassembly, washing, needle and seat inspection, reassembly and pop pressure adjustment.
Manual Section: Fuel Injection Nozzle p. 54Low feed pump delivery pressure
Worn trochoid rotors slowly starve the pump of fuel. The specifications give standard delivery pressure and volume for MP2 and MP4 pumps, a 0.1mm wear limit for the rotors, case and cover, and a 10,000 hour replacement interval for the feed pump assembly.
Manual Section: General Information p. 9Injection timing off after rebuild
On these pumps, injection timing is set by bottom clearance, and it has to be re-established whenever the hydraulic head or camshaft has been apart. The section gives the adjusting values by cam classification and the measuring procedure.
Manual Section: Adjustment of Fuel Injection Pump and Governor p. 47Guessed torques ruin hydraulic heads
Delivery holders, head bolts and rack plugs all have tight torque windows, and MP2 and MP4 values differ on several fasteners. The torque tables list the pump part and mechanical governor part fasteners so nothing gets pulled up by feel.
Manual Section: Tightening Torques for Main Bolts and Nuts p. 63Frequently Asked Questions
Which fuel injection pumps does this manual cover?
It covers the Yanmar YPD-MP2 and YPD-MP4 series fuel injection pumps, specifically models YPD-3MP2, YPD-4MP2 and YPD-4MP4, as used on Yanmar TNV series diesel engines.
Does it include tightening torque specifications?
Yes. The Tightening Torques for Main Bolts and Nuts section lists values for the pump part and the mechanical governor part, with separate MP2 and MP4 figures where they differ, such as head bolts at 18 to 22 N-m on MP2 and 28 to 32 N-m on MP4. p. 63
Can I set injection timing with this manual?
Yes. The Adjustment of Fuel Injection Pump and Governor section covers bottom clearance adjustment, which sets fuel injection timing on these pumps, including adjusting values by cam classification, plus the full governor adjustment procedures. p. 47
Does it cover injector nozzle testing and adjustment?
Yes. The Fuel Injection Nozzle section covers construction, disassembly, washing, inspection, reassembly and adjustment, and the manual specifies an injection starting pressure of 16.2 to 17.2 MPa for the YDN-12SD12 nozzle. p. 54
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.
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