Yanmar 729685-51330 / 729247-51390 High-Pressure Fuel Pump – Compact Common-Rail Architecture with Enhanced Flow Stability for 4JH/4TNV Series Engines
1. Product: 729685-51330 & 729247-51390
2. Compatible Equipment: Diesel Fuel Injection Systems
3. Manufacturer: Aftermarket OEM Replacement
4. Condition: Brand New, Fully Tested
5. Origin: ABOSEDE Diesel
6. Shipping period: 3-5 business days
7. Payment terms: T/T, Western Union, PayPal
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Product Introduction
In the design of high-pressure fuel pumps for compact diesel engines, the primary challenge is not flow capability-it is installation density. The pump must fit within the narrow engine bay of a marine vessel, the constrained compartment of a skid-steer loader, or the tight envelope of a generator set, while still delivering the rail pressure and flow stability required for modern common-rail injection. The Yanmar 729685-51330 and its service replacement 729247-51390 are high-pressure fuel pumps designed specifically for the compact 4JH and 4TNV engine families, with a radial three-plunger design that delivers up to 1600 bar rail pressure within a housing that is 35% smaller than comparable pumps. The result is a pump that meets the performance requirements of modern common-rail systems without compromising the engine's compact packaging.
Flow Stability – The Foundation of Consistent Rail Pressure
The 729685-51330 uses a cam-driven radial plunger arrangement with plungers spaced at 120° intervals, providing overlapping pressure strokes that minimise the flow interruption between plunger events. The flow ripple is measured at 4.5% at full load-a 30% improvement over two-plunger designs. This lower ripple reduces the pressure fluctuations at the rail, allowing the ECM to maintain a stable injection timing. The pump's volumetric efficiency is rated at 90%, meaning that 90% of the theoretical displacement is delivered to the rail, with the remaining 10% accounted for by internal leakage and compressibility.
Material Durability – Engineered for Marine and Industrial Environments
The 729685-51330's plungers and barrels are manufactured from a nitride-hardened steel with a surface hardness of 1100 HV and a case depth of 0.025 mm. This hardening provides resistance to the abrasive wear from particulate contamination, which is a common concern in marine and off-highway applications. The cam and camshaft are constructed from a case-hardened alloy steel, with a hardness of 58 HRC, providing resistance to the high-contact stresses of the plunger-cam interface. The pump housing is made from ductile iron, which absorbs the vibration inherent in marine and industrial operation.