BH6P120R Inline Fuel Injection Pump for WP10 Diesel

The application we stand behind is a six-cylinder diesel engine of the Weichai WP10 and WD10 families, and the P7100 series architecture is what the unit itself presents. Two things carry that application and they are the two the published data actually supports: the model designation on the plate, matched letter for letter, and the architecture on the body, counted and looked at. We deliberately do not extend that to a vehicle model list, a bore figure, an emission stage or a year range, because the sources we can cite contradict each other on exactly those points and a value we cannot stand behind twice is worse than no value at all.

A word about the engine names, because it matters here more than on most pages. WP10 is an engine-family designation published by the engine manufacturer. It is not a part number, it is not something you order, and it will never appear in the part number field of an order for this pump. When you see an engine family name printed next to a pump, read it the way you would read a size or a fitting: it tells you what the part is for, not what the part is. We name the engine family on this page because it is genuinely useful for identifying the application, and we keep it out of every number field because it is not one.

Why the plate matters more than the number range. This family publishes several model designations that differ from one another by a single letter, and the sources we can cite do not agree consistently on how those lettered forms relate. That means a range search across the family cannot serve as a fitment check; it is a coin toss with a delivery date attached. The plate is the answer: the designation on it, the row of six delivery valve holders, the governor housing on the flank, the gear-driven hub on its machined flange. Match those four things, then order, and a six cylinder injection pump bought that way arrives right the first time.

Three more identifiers worth having. If the engine is still in the vehicle, the engine code plate settles the engine variant faster than any chart. If the pump is already off, a photograph of the plate on the pump and a photograph of the drive end settle it instead. Where the pump has been replaced before, the invoice or the previous work order tells you which designation went into the engine, which is worth more than any of our catalogues. Any one of those alongside the plate on the unit is enough for us to confirm in writing.

What this page is not claiming. We are not saying that a near-identical lettered variant fits your engine, that a component number for an internal plunger or delivery valve is settled, that the published application covers an engine without a plate check, or that a pump of another architecture substitutes. BH6P120R describes one build in one family, and the plate on the unit is what identifies it. Anything beyond those lines is better answered from your own parts data, and we would rather answer it with you than assert it here.

A diesel injection pump has one job: get the right amount of fuel, at the right moment, into each cylinder in turn. On a straight-line mechanical pump that job is done the oldest way there is, and the arrangement is worth understanding before you buy anything. The body carries six pumping elements in a single row, one per cylinder. Each element has its own delivery valve holder on the top rail, closed by a threaded cap, and its own high pressure line leaving the head for its own injector. Inside the body a camshaft turns, its lobes push the plungers up, and the volume above each plunger is forced out through its delivery valve into the line.

The second thing on this pump is the governor, and it is the part most often misunderstood. A cast housing on the flank carries a mechanical all-speed governor of RSV type: flyweights, a linkage arm and a spring, all moving fuel, all deciding nothing electrical. Its job is to hold the delivery steady at idle and to cut it off as the engine approaches its governed speed. That is why the behaviour of this pump is read from how the engine runs and how it sounds rather than from a scan tool, and it is why a tired governor shows up as an idle that hunts or a top speed that will not hold.

The third thing is lubrication, and it is the most practically useful thing on this page. On this architecture the diesel fuel itself is what lubricates the plunger pairs; there is no separate oil feed to the pump. Two consequences follow, and both are expensive if you learn them the hard way. Fuel quality matters more here than on a pump with its own oil supply, because the oil doing the lubricating is the fuel you put in the tank. And an internal failure can put wear metal into the low pressure circuit rather than only stopping the pump, so a replacement fitted into a circuit that was never flushed can be destroyed within its first hour by metal that was already loose. That is the single most expensive avoidable outcome on this job.

The fourth thing is timing, and it is where a correct pump gets damaged. Because the pump is driven by a gear off the engine camshaft, its position relative to that camshaft is the timing: the lobes have to reach each element at the moment that cylinder needs fuel. The engine therefore goes to compression top dead centre on a reference cylinder before the pump is offered up, and the flange and drive gear are located loosely before anything is tightened. A pump fitted a lobe out of phase will run, and it will run badly, and it will do damage to the drive and the elements while doing it.

Once fitted, each injector draws from its own line rather than from a shared volume, which is what makes the system simple to diagnose and simple to repair one cylinder at a time. The flip side is that a fault is often confined to one element and shows up as one cylinder misbehaving, which is diagnostically useful if you know to look for it. The engine also tells you through how it runs rather than through a warning light: a hard start that is worse when warm, an idle that will not settle, power that arrives at idle and disappears under load. Each of those is examined properly in the symptoms section below.

Where our supply differs is what arrives rather than how the part works. Original equipment supply comes through the manufacturer’s own channels, and a buyer whose paperwork requires a factory boxed part does need to go there. What we supply is a new compatible inline pump — a new unit for the same job, built to the same published architecture, sold under the Vidishi Auto brand, carrying the same model designation, at a single-piece minimum with no core return. That last point matters on this job more than on an electronic system: nothing has to come back, there is no exchange loop to manage, and the removed pump stays with you for the warranty file.

One thing we do not do is dress that up. The BH6P120R pump we ship is ours, not an engine or equipment manufacturer’s. The model designation, the series name and the engine-family names appear on this page so you can match the pump you are replacing. They are references for identification and fitment, not a claim about who made the part, and the plate visible in the photography is recorded as a marking carried by the photographed goods. The markings on that plate describe that unit rather than the place of manufacture of the goods we supply, which is why no country of manufacture is claimed anywhere above. The buying guides hold the general method for confirming any diesel part from the unit itself, and the glossary explains the terminology if any of the names above are unfamiliar.

How we label data. Confirmed means a value read directly from the goods we handle, including the architecture visible in the photography and the drive end and fittings on the body. Reference means a series designation, a design name or a cross reference quoted so your paperwork can be matched, and carrying no claim about origin. Not published means the field is left blank on purpose — a pressure figure, a bore, a component number or a fitment list that we cannot source would be worse than an empty cell, because it would end up in somebody’s parts order or somebody’s engine settings.

What is in the box. One complete six-cylinder inline fuel injection pump: the cast body with its six pumping elements under the top rail, the six delivery valve holders with their threaded caps and clamp rings, the mechanical all-speed governor housing on the flank with its linkage arm, the camshaft drive hub with its splined stub and retaining nut on the machined mounting flange, the integrated supply pump in the lower body, the solenoid body and the data plate, all as photographed. New sealing washers and a fresh filter element are required at fitting and neither is asserted as included for this line. Nothing on this page is sold loose from the pump, and internal components such as plunger pairs, delivery valves and governor parts keep their own listings for buyers who want a rebuild rather than a replacement.

Read the table from the top, because the order matters. BH6P120R is the supplier model designation and it is the only row you should order against. The rows beneath it are of a different kind, and mixing them up is how orders go wrong. P7100 series is an architecture name: it tells a parts clerk which kind of unit to look for on the shelf and which service manual applies, and it tells you nothing about who built the unit in your hand. WP10, WD10 and WD12 are engine-family designations: they tell you what the pump is for and they are never orderable numbers. Used as a BH6P120R cross reference map, the table is a boundary as much as a bridge.

The series row is worth reading twice, because series names are routinely mistaken for manufacturers. A series designation is a pattern: it says this pump belongs to a family of pumps built to a shared set of dimensions and a shared service method, and it is used across the trade by more than one maker. Reading it as a brand is the error that ends with a buyer who believes they have received a product of somebody else’s make. What arrives here is ours, built to the published pattern for the same job, and we say so plainly rather than borrowing a name.

The engine-family rows carry a different warning. An engine family name looks like a part number because it is short, alphanumeric and printed next to parts on catalogues and listings. It is not one. WP10 identifies a series of engines; it does not identify a pump, it cannot be quoted on an order, and it will not appear in the part number field of anything we supply. We print these rows because naming the application is genuinely useful to a buyer who knows their engine, and we label them as fitment wording because that is exactly what they are.

What the table deliberately does not do is extend itself. It does not list the engine-side numbers that circulate alongside this model in the trade, because each of those attaches to one individual build and one individual engine application rather than to the model as a range, and a list of them here would read as an interchange table that no source actually supports. It also does not list the near-identical lettered variants of the model designation, because the sources disagree about how those relate and we will not turn a disagreement into a claim. Our comparison charts set out the number families we can evidence, and the buying guides cover the general method for confirming any diesel part from the unit itself.

The practical difference shows up in the delivery test. When delivery collapses under load, the vehicle either runs on compromised fuelling until something else breaks, or the workshop fits a known-good pump and the figure comes straight back. Keeping a matched spare — correct designation on the plate, six holders in one row, governor present, gear drive intact — turns a two-week vehicle stop into a same-week swap. That is the case for holding one of these before anything has failed, and it is why a single-piece minimum is the sensible purchase here: one pump is one job, and the shelf spare is the one that earns its keep.

• Hard starting that is worse when warm — A mechanical governor and a worn element both take time to respond as the engine heats up, and an inline mechanical engine wants its delivery right from the first compression. A start that is brisk cold and long hot is a signature worth reading properly rather than resetting the fuel system.
• An idle that hunts or will not settle — At idle the governor is holding delivery steady for every cylinder at once. A governor that has lost its authority shows up as an idle that will not hold, often with a shake that no mounting fault explains.
• Loss of power only when the engine is worked — When the operator asks for load the pump has to deliver more, and that is the demand a tired element struggles to meet. The engine feels flat exactly when it is asked for more and fine at idle, which is what makes it easy to misread as a driving complaint.
• Smoke under load — Fuel delivered in less volume than the engine asked for does not atomise the way it should, and it leaves the stack as smoke. On a straight-line mechanical pump with one element per cylinder this points at the element on whichever cylinder the smoke colour suggests, and at the pump as a whole once the reading moves across all six.
• Rising fuel consumption — Fuel that spills past a delivery valve that is no longer seating cleanly is measured again on the next stroke, so the gauge moves faster than the work done and the tank empties sooner than the hour meter suggests.
• Delivery that falls away under load — The measurement that settles it. Delivery compared at idle and then with the engine worked points at the pump when the figure collapses under load and no filter or injector work changes it, and it is the single most useful number to bring us with an enquiry.
• Metal in the filter bowl after a failure — On this architecture the diesel itself lubricates the plunger pairs, so an internal failure can put wear metal into the tank, the lines and the filter housing along with the low delivery that stopped the engine. Fine particles in the filter bowl, or a return line running unusually hot, are the reasons to stop and flush rather than fit and drive.
• A change in the sound of the drive — A gear-driven pump that has lost mesh with its coupling is audible before it is measurable, and continuing to run it wears the drive stub as well as the elements. If the drive changes after the pump was fitted, stop and check the coupling rather than assuming the new unit is at fault.

The pattern worth holding on to is the one that moves across all six cylinders together. A single worn element or a single dirty injector shows up on one cylinder and leaves the engine steady on the other five, and on a straight-line pump you can often feel which cylinder it is. A tired pump or a governor that has lost its authority takes the whole engine down together, because one unit feeds all six lines. That distinction does more diagnostic work than any code name, and it is why we would rather have your delivery readings than a code you have decoded from a list. The fault code guide explains how to read stored data on a mechanical engine, and our maintenance guide covers the filter and water separator intervals that keep this circuit healthy.

The second pattern is specific to this architecture and worth its own paragraph, because it changes what you do next. Where the fuel itself lubricates the plunger pairs, a failure can send wear metal through the tank, the lines and the filter housing along with the low delivery that stopped the engine. Fine particles in the filter bowl, or a return line running unusually hot, are the reasons to stop the engine and flush the circuit rather than fit the pump and hand the vehicle back. A replacement fitted into a circuit that was never cleared is a second failure bought on the same day.

• Step 1. Bring the engine to compression top dead centre on the reference cylinder before anything is unbolted
  On this architecture the pump delivers to each cylinder in a fixed relationship to the engine camshaft, so timing is set by where the engine is, not by how the pump happens to sit. The reference cylinder goes to compression top dead centre before the old unit is released, and that position is what everything that follows is referenced to.
• Step 2. Flush the whole low pressure circuit if the old unit failed internally
  The diesel lubricates the plunger pairs on this pump, so a failure can leave wear metal in the tank, the lines and the filter housing. Drain all of it, fit new filters, and only then fit the new unit. This step is the single biggest cause of a second failure and it is the one most often skipped on a pump sold as a drop-in.
• Step 3. Clean the mounting face and the spill port before opening anything
  Wash around the pump, blow the sealing face down, and only then release the bolts. Grit that falls onto that face ends up between the two surfaces, and the new pump will weep from its first minute.
• Step 4. Unbolt evenly and support the housing
  Work the bolts in sequence rather than freeing one corner at a time. The housing has to lift straight off the engine rather than at an angle, and nothing on the drive end may be levered against the gear on the engine.
• Step 5. Inspect the drive hub, the splined stub, the gear and the surrounding material
  Check the hub, the stub, the engine gear and the surrounding material for wear, burrs and stray debris. A drive turning against a worn coupling, or against one that has picked up metal, damages the new pump inside its first hour of running, and the timing that follows depends on that coupling being true.
• Step 6. Offer the new unit up loosely and locate it before anything is tightened
  On this architecture the intermediate flange and drive gear are offered up to the engine gear loosely and located before the fasteners go in, so the unit sits at the timing position it came off. Tightening first and then trying to rotate the unit by hand is how an injection pump gets fitted out of phase.
• Step 7. Fit new seals and a fresh filter element
  A fresh seal goes under the refitted pump and the filter element is renewed rather than reused. Reused seals and a reused element are the most common causes of both a weep and an early return of the same fault.
• Step 8. Set speed, bleed the lines and verify before the engine goes back to work
  Set the governor to the figure for the engine, bleed each high pressure line until it shows no air, then run the engine and confirm delivery at idle and again under load before the vehicle leaves. Check the filter bowl again after the first run, and re-check the timing once everything is warm.

Two notes on what we deliberately do not print. We do not publish the timing angles, the drive phasing or the tightening figures, because all three belong to the engine application rather than to the part, and a figure copied out of a product page into a workshop manual is how a good pump gets damaged on a correct fit. Take them from the engine manual for the vehicle in front of you and confirm them against the unit coming off. And we do not publish a diesel fuel injection tightening figure as a shortcut, because the mount, the lines and the governor setting each have their own value and they are not interchangeable. The installation guide covers the surrounding routine, and the glossary defines the terms if any of the above are new to you.

Every BH6P120R pump is covered by a 12-month warranty against manufacturing defects. That covers a unit that arrives out of specification or fails early because of how it was made. It does not cover damage from contaminated fuel, from water in the system, from a filter changed too late, from incorrect fitting, from a drive coupling torqued beyond its figure, from timing set up incorrectly, or from a separate fault elsewhere in the fuel circuit. It does not extend to labour or to the vehicle. It is a supplier warranty from Vidishi Auto and it is not a warranty from any engine or equipment manufacturer — we are not a dealer for any of them and no cover from any of them travels with this part.

The one condition we ask about every time is whether the circuit was flushed when the old unit came out, because on this architecture that is the single most common reason a replacement pump fails early and the single easiest thing to get wrong on a job where somebody is under time pressure. The fuel lubricates the plunger pairs, so metal left in the circuit is the mechanism, not a theory. Tell us what was done and we can tell you quickly whether a claim is likely to stand. If you would rather settle that question before you order, the contact page is the fastest route to a written answer.

The minimum order quantity is 1 piece, and the reasoning is worth stating rather than leaving you to work out. Demand for a pump of this type arrives one fault at a time, because a failure takes a vehicle off the road and the repair is done once, properly. A single unit covers that job, and it lets one pump sit on the shelf as the known-good unit for delivery testing before anything else is committed. From there the line scales normally — a fleet running several engines will take a set per vehicle, and a distributor will take them alongside the rest of a fuel system order.

What we do not do on this line is pretend the part is something it is not. The unit we ship is a new compatible replacement sold under the Vidishi Auto brand. It is not manufacturer-branded and it is not a factory boxed original. That matters commercially as well as legally: if your incoming goods inspection needs a specific brand on the paperwork, this is not that product, and we would rather tell you now than have a delivery rejected. The help centre covers ordering and documentation questions.

The package size and gross weight in that table are a packing estimate, and we label it that way rather than quietly presenting it as a specification. No source we can stand behind publishes a packaged figure for this number, so we give you a figure we can pack and weigh against rather than a manufacturer specification we cannot evidence. If your freight is calculated on volumetric weight rather than actual weight, tell us the destination and we will confirm the chargeable weight against the carton we actually use. The shipping page sets out the full documentation and delivery terms, and the order tracking page is where to follow a shipment once it has left.

On the protective side, the two areas we watch are the drive hub and splined stub and the governor linkage arm. A stub knocked out of register will not seat properly against the engine gear and will damage the new pump within hours, and a bent linkage arm is a fault that looks like a governor problem for weeks afterwards. Both are packed protected on every unit, and both are worth checking on arrival before the box goes into stores.

An inline mechanical injection pump is a handful of large, precisely machined parts with a handful of very close fits inside it, so this line is checked at unit level rather than by sample. Every unit passes an incoming check on the model designation, a count and inspection of the six delivery valve holders along the top rail, an inspection of the governor housing with its linkage arm and capped ports, a confirm that the drive hub, the splined stub and its retaining nut are present and undamaged, a check that the mounting flange face and the threaded ports are clean and free of obstruction, and a packed-weight confirmation against the documented figure. The supplier shows an ISO 9001 system certification badge on the product photography, which we record as a supplier statement rather than as a certificate we issue.

Rather than publish reviews we cannot verify, we tell you what we will actually put in writing: a written fitment confirmation against the plate you send us, a written quote against your quantity and destination, and a warranty position on any claim that follows. If you need a supplier who will sign a specific inspection or conformance document with the order, ask before you buy rather than after, because the answer depends on what the document is. The help centre covers the documentation we can provide, and the partner programme page is the route for a standing arrangement that needs more than a one-off order.

Support is not an add-on on this line — it is how most of these orders get placed correctly. It costs nothing before you buy: send the designation read off the plate on the unit you are removing, the engine code and the vehicle details, and we check the whole set against what we supply before quoting. That last item is the one people skip, and it is the one that matters most here, because this family carries near-identical lettered variants and a supplier matching on a number range rather than on the plate will not catch the difference. Two minutes with the plate in front of you is cheaper than a pump that arrives and does not settle the fault.

Two things we will not do, whatever the order size. We will not quote a fitment we cannot evidence, and we will not ship a pump matched on an engine family name when the plate on the old unit is available. If that costs us an order, it is still the right call: an injection pump that arrives mismatched or fitted out of phase costs a workshop a second removal, and that is the failure we exist to prevent. If anything on this page is unclear, the contact page lists every route to us, and a written answer is always better than a guess on a workshop schedule.