Kubota Injection Pump 1J801-50500 | Genuine Supply Pump for V2403-CR and D1803-CR

The Kubota 1J801-50500 is the genuine high pressure supply pump, Kubota catalog description “PUMP,ASSY(SUPPLY)”, for Kubota’s Tier 4 common rail engine family. Built by Bosch for Kubota, it generates the rail pressure that feeds the injectors on D1803-CR and V2403-CR engines used in Kubota compact excavators, wheel loaders, tractor loader backhoes, and L, MX, and M series tractors. Kubota has superseded this number to 1J801-50501 and then 1J801-50502. All three numbers are the same interchangeable pump, and we supply the current genuine part. Valley Fuel Injection is an authorized Kubota dealer with a full common rail repair shop behind every part we sell.

Application & Fitment

This supply pump is confirmed for Kubota Tier 4 common rail engines:

• Kubota V2403-CR (Tier 4, including the V2403-CR-EF03 variant)
• Kubota D1803-CR (Tier 4)

Some catalogs also reference the V2403-CR-TIE4BG-MLR1 and D1803-T variants for this part number.

Reported equipment applications for 1J801-50500 include:

• Excavators: Kubota KX040-4, U48-5
• Wheel loader: Kubota R430
• Tractor loader backhoes: Kubota L47 TLB, M62 TLB
• L series tractors: L3301, L3302, L3560, L3901, L3902, L4060, L4701, L4760, L4802, L5060GST, L5460, L6060
• MX series tractors: MX4800, MX5200, MX5400, MX5800H, MX6000
• M series tractors: M5660SUH, M5660SUHD

This machine list spans both D1803-CR and V2403-CR engines, and Kubota used more than one fuel system configuration across these models. Please verify fitment by engine serial number before ordering. Call us with your machine model and serial number and we will confirm the correct pump in the Kubota parts system before anything ships.

Cross-Reference Part Numbers

• Bosch 0445020200 (the Bosch service number for this common rail pump)
• Kubota supersessions: 1J801-50501, 1J801-50502 (current number, fully interchangeable)
• Kubota remanufactured exchange: KEARP-1J801
• Caterpillar 477-7689 Pump AS-Fuel Injection, used on CAT branded Kubota based engines, part of CAT pump group 477-7983 and kit 486-5200
• Bosch 0445020187 and 0445020166 appear on some aftermarket cross lists; verify these against your serial number before relying on them

Frequently Asked Questions

Is 1J801-50500 the same pump as 1J801-50501 and 1J801-50502?

Yes. Kubota superseded 1J801-50500 to 1J801-50501 and then to 1J801-50502. The pumps are interchangeable, and ordering any number in the chain gets you the current genuine part.

Should I replace anything else when this pump fails?

Often, yes. When a high pressure pump fails it can send metal debris through the rail, lines, and injectors, and that debris will quickly damage a new pump if it is not cleaned out. Our common rail repair shop can test your injectors and tell you exactly what your engine needs, so you only fix it once.

How do I know this pump fits my machine?

The safest way is your engine serial number. The D1803-CR and V2403-CR family used more than one pump and rail configuration, so call 530-668-0818 with your machine model and engine serial number and we will verify the exact part before you buy.

Why do I see this pump cheaper online?
Short answer: it is usually not the same part — and a pump failure does not stay in the pump. Read why ↓

Search any OE number and eBay, Amazon and a dozen storefronts will show it well under dealer cost, sold by outfits with no name, no address and no phone number. We lose business to those listings every week — and we see a lot of them come back through our shop. Here is what is actually different.

• The part number proves nothing on its own. Counterfeit injectors and pumps are stamped with the same OE numbers as the real thing, in housings cast to look identical. The number in the listing title tells you what the seller claims it is, not what came off an OE line.
• “Remanufactured” is not a regulated word. A genuine reman unit is stripped to bare components, has its wear parts replaced — nozzle, plunger and barrel, solenoid, seals — and is then run on a calibration bench until it meets the original flow and response spec. A cheap one is very often cleaned, resealed, painted and shipped. Both get called remanufactured.
• No full teardown, so no idea what is worn. A proper rebuild means the unit comes apart completely and every part gets inspected and measured against spec — not just the ones that are obviously bad. Skip the teardown and you are reusing worn internals inside a freshly painted housing. It will run on the truck. It will not last.
• No factory-spec bench load testing. A unit is not finished until it has been run under load on a test bench and made its numbers across the range, not just at one easy point. That bench time is most of what you are paying for. Sellers working on price cut it first, because nobody can see it in a photo.
• The warranty has to be honored by someone. Everything we remanufacture in house carries a one-year warranty, with 30 days on electrical components. Parts we supply as an authorized dealer carry the manufacturer’s own warranty. Either way you call us, a real shop in California, and we sort it out. A marketplace warranty usually means shipping the part overseas at your own cost and hoping for a reply.
• No core program. We credit your rebuildable core back in full. Discount sellers generally will not take one, so the gap narrows the moment you account for the core you are now stuck holding.
• A pump failure does not stay in the pump. When a high-pressure pump comes apart it sends metal downstream through the rails, the lines and every injector. That is the whole reason fuel contamination kits exist. A pump that was never tested to spec is the cheapest possible way to buy that repair.

We are an authorized dealer and a working fuel-injection shop — we have been rebuilding and testing this hardware in Woodland since 1993, and the people who answer the phone are the people who run the benches. Not sure this is the right part for your engine? Call us with your serial number before you order and we will confirm it. Send your rebuildable core back and the core charge is refunded. And if a price somewhere else looks too good, call 530-668-0818 and we will tell you straight whether it is a deal or a problem.

Why Buy From Valley Fuel Injection

We are Valley Fuel Injection & Turbo in Woodland, CA, diesel injection specialists since 1993 and an authorized Kubota dealer. We are not a box mover. We test, diagnose, and repair common rail systems every day, so when you buy genuine Kubota engine parts from us you also get straight answers on diagnosis, installation, and what else to check. If you would rather hand off the whole job, our diesel fuel injection services cover everything from injector testing to complete fuel system repairs.

Pricing and Availability

Call 530-668-0818 for current pricing and availability on the genuine Kubota 1J801-50500 supply pump, or contact us online. Please have your engine model and engine serial number ready so we can confirm fitment and the current superseded part number before you order.