Remanufactured fuel injection pump, cross-ref 729642-51330, 4D88E, 4D88-5. Bench-tested before shipment.
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729642-51330 is supplied as a remanufactured replacement fuel injection pump. Cross-reference numbers: 729642-51330, 4D88E, 4D88-5, PC50MR-2, PC40MR2. Application recorded for this part: Fits Komatsu — 4D88, 4D88E, 4D88-5 PC50MR-2, PC40MR2. This pump has two jobs that are easy to conflate: raising fuel to injection pressure, and metering the correct quantity at the correct moment. Wear affects both. The result is usually a combination of harder starting, drifting timing and visible smoke rather than one clean fault. Look for extended cranking, especially hot, poor throttle response, smoke across the rev range, fluctuating idle speed, and a gradual rise in consumption that cannot be explained by duty cycle. Eliminate the cheap causes first: filter condition, lift pump output, suction-side air leaks, fuel quality. Only then have delivery quantity and timing tested before committing to a replacement unit. Fitting notes: timing is everything here. Set the pump against the engine's timing marks rather than forcing anything, prime thoroughly before cranking, and check that the lift pump is delivering adequate supply pressure. Also replace the mounting seal and confirm there is no air left in the system before the first start. Rebuilt rather than refurbished: full teardown and measurement, worn components replaced instead of cleaned and reused, sealing surfaces restored to specification, then bench calibration and testing. The record is what separates this from a used part — we can provide the test sheet for your order. Covered by a 12-month warranty.
| Part number | 729642-51330 |
| Condition | Remanufactured (not a genuine OEM new part) |
| Cross-reference | 729642-51330, 4D88E, 4D88-5, PC50MR-2, PC40MR2 |
| Application | Fits Komatsu — 4D88, 4D88E, 4D88-5 PC50MR-2, PC40MR2 |
| Process | Disassembled, cleaned, measured, wear parts replaced, machined to specification |
| Bench test | Delivery, return flow, opening pressure and leakage recorded before dispatch |
| Warranty | 12 months |
Three very different things are sold under similar descriptions. Here is what separates them, and what to ask before you buy.
Read the guide →The pump sets pressure, quantity and timing. Here is how wear shows up, and the checks that separate pump faults from supply faults.
Read the guide →Water, dirt and misfuelling damage common rail components differently. What to check, and why cleaning the system matters as much as replacing parts.
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