Inline Diesel Injection Pump Rebuild Service (Bosch A, Denso, Zexel)
The Bosch A-model, and the Denso and Zexel inline pumps built on the same design, powered decades of Japanese and American agricultural, industrial, marine, and light-truck diesels, and Valley Fuel Injection has been rebuilding all of them the right way for decades. These are mechanical plunger-and-barrel pumps, one pumping element per cylinder driven by an internal camshaft, and they are among the most durable injection pumps ever made. When one finally wears out, a proper inline injection pump rebuild is almost always faster, cheaper, and better than hunting down a replacement that may no longer be manufactured. We rebuild your own core and calibrate it to the maker’s specification, so you get a pump matched to your engine instead of a generic replacement or an imported knockoff.
The Valley Fuel Injection Difference
We are a rare breed. There are not many shops left in the country with the training, the certification, and the test equipment to rebuild a diesel injection pump to factory standard, and fewer still that do it at our level. This is not a cheap imported knockoff and it is not a throw-together seal-kit job. It is a genuine, certified, factory-spec rebuild, done by hand and proven on the bench before it ever leaves the building.
When you send an inline pump to Valley Fuel Injection, it is rebuilt by licensed, factory-certified diesel technicians, to the same standard the pump held the day it left the factory, and it is backed by a real warranty. That is the whole point of what we do.
Applications We Rebuild
Inline plunger-and-barrel pumps turn up on an enormous range of equipment. The most common we see:
| Engine / Equipment | Typical Applications |
|---|---|
| Yanmar & Kubota | Tractors, excavators, marine auxiliaries, and gensets with Denso or Zexel inline pumps |
| Cummins early inline | Older Cummins engines running Bosch A-model inline pumps |
| Isuzu, Komatsu & Mitsubishi | Japanese industrial and equipment diesels with Zexel and Denso inline pumps |
| Ag & marine | Case, John Deere, Allis-Chalmers era tractors and small marine diesels |
Common Inline Pump Models We Rebuild
Three pump families account for nearly all of the inline work that comes across our bench:
Bosch A-model (A-pump): American and European ag and industrial inline diesels
Denso inline (105015 series): Yanmar, Kubota, and other Japanese diesels
Zexel inline: Isuzu, Komatsu, Mitsubishi industrial engines
Not sure which pump you have? It does not matter. If it is an inline plunger-and-barrel pump, we rebuild it. Read the numbers off the tag on your pump, call 530-668-0818, and we will identify it and quote your rebuild.
Signs Your Inline Pump Needs a Rebuild
- Hard starting or long cranking, hot or cold
- White smoke at idle that never fully clears
- Low power or a diesel that will not pull like it used to
- Rough or uneven running caused by cylinder-to-cylinder fuel imbalance
- Fuel leaks at the delivery valves or from the cambox
- Governor surge, hunting, or an idle that will not settle down
- Engine oil level rising or smelling of diesel, a sign the pump is leaking fuel into the oil
How We Rebuild Your Inline Pump
A Valley Fuel Injection rebuild is not a seal kit and a coat of paint. Every inline pump is torn completely down and built back to the maker’s standard, one measured part at a time:
- Complete teardown and inspection. The pump comes fully apart and every component is inspected against factory wear limits, including the internal camshaft and its tapered-roller bearings. Nothing is reused on assumption.
- Deep cleaning. Every part is thoroughly cleaned so we are building on bare, spotless metal, not old varnish and debris.
- Plunger-and-barrel and delivery valve service. Each plunger-and-barrel assembly and each delivery valve assembly is measured and replaced as needed with factory-certified parts, never cheap generic substitutes.
- Governor linkage service. The governor linkage, including the tensioning and swivelling levers, is serviced and set so the pump responds crisply and holds a steady speed under load.
- New gaskets and seals throughout. Every gasket and seal in the pump is replaced, which is what stops cambox leaks and fuel dilution of the engine oil for good.
- Calibration and testing on real machines. The finished pump goes on a professional test bench where per-cylinder fuel delivery, balance between cylinders, and governor settings are calibrated to the maker’s specification, following the Bosch, Denso, or Zexel test plan for your exact pump, and proven before it ships.
That final step is what separates a real rebuild from a parts swap. Anyone can bolt in a seal kit. Very few shops can put your pump on a bench, balance every cylinder to spec, and stand behind the result.
Our Warranty
We control every step of the rebuild, so we stand behind it. Every pump and injector we rebuild carries a 1-year warranty. Electrical and electronic components are warrantied for 30 days. Clean, water-free fuel and a healthy supply system are essential to pump life, so we recommend fresh fuel filters at installation to protect your rebuild.
What an Inline Pump Rebuild Costs
Typical Rebuild Cost
$1,350 to $2,800 typical range
Most inline pump rebuilds land between $1,350 and $2,800, with a typical job around $2,200. Those figures come from 57 inline pump rebuilds we have completed in the last 18 months, not markup guesses. Pumps with heavier wear, or that need plunger-and-barrel or camshaft parts, run toward the top of the range. Because every rebuild is priced on your pump’s actual condition, we give you a firm quote after inspection, before any work begins.
Prices above cover the service and parts. Any applicable sales tax, plus shipping and small shop fees (such as a hazardous-waste disposal fee), are added at invoicing, so your quote reflects the full out-the-door number before any work begins. Buying tax-exempt? Qualifying diesel repair shops, fleets, farms, and agricultural operations can purchase tax-free. Set up tax-exempt purchasing by submitting your resale or exemption certificate once, and every qualifying order is tax-free going forward.
How It Works · Call for Pricing and Availability
Because every inline pump rebuild is done on your own core, pricing depends on the pump’s condition and the parts it needs, so we quote each job individually. Here is the process:
- Call us with the numbers on your pump tag so we can identify it and talk through your symptoms.
- Ship the pump to us or drop it off. We tear it down, inspect it, and give you a firm quote before any work begins.
- We rebuild and bench-calibrate the pump, then return it ready to install, backed by our warranty.
Call 530-668-0818 for pricing and turnaround, or start your rebuild online → and we will walk you through shipping it in.
Why Valley Fuel Injection
Valley Fuel Injection & Turbo is a full-service, factory-certified diesel fuel injection shop in Woodland, California, serving truck owners, farmers, fleets, and other repair shops across the country. We are a Bosch-authorized service center with the tooling, the test equipment, and the certification to rebuild inline pumps correctly, and we have been doing it long enough to have seen just about every way an A-pump, Denso, or Zexel can fail. When a shop cannot fix it, they send it to us. Ship your pump from anywhere or visit us at our Woodland shop.
Want more background before you send yours in? If your pump is on a Yanmar, start with our Yanmar injection pump problems guide. For farm equipment of any make, our tractor injection pump rebuild guide walks through the whole process from diagnosis to reinstall.
Frequently Asked Questions
How much does an inline injection pump rebuild cost?
Most inline pump rebuilds run between $1,350 and $2,800, with a typical job around $2,200. That range comes from 57 real inline pump rebuilds we have completed in the last 18 months, not a markup guess. Where your pump lands depends on its condition and the parts it needs, so we give you a firm quote after teardown and inspection, before any work begins. Call 530-668-0818 for current pricing.
Do I send you my pump, or do you have one in stock?
This is a rebuild service for your own core. You ship us your pump or bring it in, we rebuild and calibrate it, and we send it back matched to your engine. Rebuilding your core is usually faster and less expensive than sourcing a replacement, and many of these inline pumps, especially older Denso and Zexel models, are no longer manufactured at all.
Can I mail my pump in from out of state?
Yes. We rebuild inline pumps for customers nationwide. Remove the pump, drain the fuel, pack it securely in a sturdy box with plenty of padding, and ship it to our Woodland, California shop. We tear it down, inspect it, quote the job, and return the finished pump bench-calibrated and ready to install. You can also start your rebuild online and we will walk you through shipping.
What warranty comes with the rebuild?
Every pump and injector we rebuild carries a 1-year warranty. Electrical and electronic components are warrantied for 30 days. We control every step in-house, from teardown through final bench calibration, which is why we can stand behind the work. Clean, water-free fuel and a healthy supply system are essential to pump longevity, so we recommend fresh fuel filters at installation to protect your rebuild.
Do you rebuild Denso and Zexel inline pumps, or just Bosch?
All three. The Denso and Zexel inline pumps are built on the same plunger-and-barrel design as the Bosch A-model, and we calibrate each one to its own maker’s test plan, whether that is a Bosch, Denso, or Zexel specification. They are common on Yanmar, Kubota, Isuzu, Komatsu, and Mitsubishi diesels, and they come across our bench constantly.
How long does a rebuild take?
Turnaround depends on our current shop schedule and parts availability for your specific pump. Some parts for older Japanese and American inline pumps take time to source, so we give you an honest timeline when we quote the job. If your tractor, boat, or truck is down and you need it back fast, tell us when you call and we will do our best to prioritize it.
What makes a Valley Fuel Injection rebuild different from a cheap replacement pump?
We are one of the few certified shops left that rebuilds these pumps to true factory standard. Every component is inspected against wear limits, including the camshaft and its bearings, and replaced as needed with factory-certified parts. Then the pump goes on our test bench, where per-cylinder delivery, balance, and governor settings are calibrated to the maker’s spec and proven before it ships. A parts swap or a used pump cannot match that, and ours is backed by a 1-year warranty.
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