Yanmar’s TNV engines are the small diesels that do big work: mini excavators, skid steers, compact tractors, light towers and gensets. Plenty of them wear another company’s paint, so many owners do not realize they have a Yanmar until the parts counter asks for the engine model.
Mechanical TNV engines use Yanmar-branded injection pumps, most often the distributor-type MP pump, with the YPES inline pump showing up on some versions. Yanmar’s pump-to-engine pairings vary by version and application, so we will be straight with you: the number on your pump is the final word.
We can help assess service options for both families.
Which Pump Is on My Yanmar TNV?
Yanmar engines do not have model years the way trucks do. They have engine models and pump numbers, so this table runs by engine.
| Engine | Pump number clue | Injection pump | What to know |
|---|---|---|---|
| 3TNV84 and 3TNV88 | 729xxx-51xxx | Yanmar MP pump | Distributor type, listed as YPD-MP with MP2 and MP4 versions |
| 4TNV84 and 4TNV88 | 729xxx-51xxx | Yanmar MP pump | Four-cylinder versions of the same family |
| Some 3TNV82A and TNV88 | 719xxx-51xxx | Possibly Yanmar YPES | |
| 4TNV94L and 4TNV98 | Yanmar MP pump on some versions | Later emissions versions may use electronic injection | |
| Smaller TNV engines | Ship it in and we will identify it |
Here is the catch: the same engine model can carry different pump numbers depending on its version and the machine it went into. Parts listings show both 719 and 729 numbers on 3TNV82A and 3TNV88 engines, so read the tag before you order.
The Yanmar MP Pump: One Plunger, Every Cylinder
The MP is a distributor-type pump. A single pumping element pressurizes fuel and sends it to each cylinder in turn, like a mail sorter dropping one envelope into each slot down the line. Fewer moving parts than an inline pump, and a lot of precision packed into a small housing.
You will see it called the YPD-MP, MP2 or MP4, and its numbers follow a 729xxx-51xxx pattern. Small pump, tight tolerances: a little water or grit goes a long way inside one.
Bench Notes: Compact equipment often sits between jobs. Stale fuel and water left in a small distributor pump can stick its precision parts, which is why a machine that ran fine in the fall may refuse to start in the spring.
Yanmar YPES: The Inline Option
The YPES is Yanmar’s inline pump, with one plunger per cylinder lined up in a row. It appears to carry 719xxx-51xxx numbers on some TNV82A and TNV88 engines. Smaller Yanmar engines may use other designs, including the single-plunger YPFR. Our Yanmar pump repair page covers the full family.
Shop Talk: Yanmar engine names are easy to decode. In 3TNV88, the 3 is the cylinder count and the 88 is the bore in millimeters. A 4TNV98 is a four-cylinder with a 98 mm bore.
Common Yanmar TNV Pump Problems
- Hard starting, especially cold or after a long sit.
- Low power and bogging under load.
- Hunting idle. Governor wear or sticking internals.
- Smoke. Timing, wear or injectors. Our hard start and smoke guide helps sort it out.
- No start. A failed fuel stop solenoid can shut everything down.
- Leaks. Aging seals. See our injection pump leaks guide.
How to Tell What You Have
Start with the engine nameplate, which gives the model, such as 3TNV88 or 4TNV98. Then read the tag on the pump for the Yanmar number, 729xxx-51xxx or 719xxx-51xxx. If the machine maker added its own part number, write that down too.
Owner’s Tip: Drain the water separator, change the fuel filter and bleed the system as your operator’s manual shows. Turn the key on and listen for the stop solenoid to click before you blame the pump.
Ship It Right: Include the engine model, the machine make and model and every number on the pump tag. Cap the ports and pack the pump so it cannot shift.
Questions about Yanmar TNV Injection Pump Repair
My machine is not a Yanmar. Could the engine be?
Very possibly. Many compact equipment brands use Yanmar engines. Check the engine nameplate; if it says TNV, you are in the right place.
What is the difference between 729 and 719 pump numbers?
They are different Yanmar part numbers, and they may point to different pump types. Send us the full number and we will identify your pump before any work starts.
Should I rebuild my pump or buy a new one?
It depends on condition, availability and how soon you need the machine back. Our rebuild vs reman vs new guide walks through the choice.
How is a Yanmar pump service plan established?
For Yanmar TNV Injection Pump Repair, the available path follows what inspection actually finds—not a universal rebuild recipe. DCT reviews the engine generation, original equipment, failure history and part number, whether the correct service parts and calibration information are available, and which work the customer chooses to authorize. Any exchange option is confirmed for the exact part rather than assumed from the family name. Explore how repair options are compared.
Small engine, big job. Whether yours digs trenches, moves pallets or keeps the lights on, its pump deserves a proper bench. Start a Mail-In Repair or request a repair evaluation.