How to Remove, Time, and Reinstall an Agricultural Injection Pump

How to Remove, Time, and Reinstall an Agricultural Injection Pump

How to Remove, Time, and Reinstall an Agricultural Injection Pump

Introduction

The guide walks you through how to correctly time, remove, and reinstall an agricultural injection pump, particularly for John Deere applications using rotary-style Roosa Master (later Stanadyne) pumps. These instructions apply broadly to pumps from the 1960s to the 1990s before emissions controls altered the design.

Common Symptoms of a Failing Injection Pump
The most common issue in John Deere tractors is governor ring failure:

  • The engine starts, runs briefly, then shuts down.

  • This cycle repeats, often caused by disintegrating governor ring

    material clogging the return line and increasing internal pressure.
    If you have trouble starting or experience shutdowns, the     injection pump is usually the culprit. Tests are available if needed—contact the shop for help.

    Preparation Tips Before Removal

  1. Penetrating Oil:

    The night before you start, spray the pump’s mounting bolts, injectors, and fuel line bolts thoroughly to loosen any buildup from years of use.

  2. Remove Injectors:

    • This makes it easier to turn the engine by hand during the

      timing process.

    • It’s also a good idea to service your injectors while you’re

      replacing or rebuilding the pump for optimal performance.

      Timing the Pump Before Removal

To avoid extra work later:

  • Time the pump before removal using the timing window next to the pump’s nameplate (usually marked “Roosa Master” or “Stanadyne”).

  • Remove the two screws on the timing cover to expose two metal plates:

    - One is fixed, the other rotates with the engine, (remember, the pump rotates at half engine speed)

  • Turn the engine by hand (not with the starter) until the marks align —this means the pump is in time and ready for removal.

    Pump Removal Steps

  1. With timing set, remove:

    • Three mounting nuts.

    • Fuel supply and return lines (cap them off to prevent spills).

  2. Slide the pump back and set it aside for service.

Reinstallation Tips

Once serviced, reinstall the pump:

  • Replace the umbrella seals on the pump shaft. These prevent fuel and engine oil from mixing.

  • Do not reuse old seals, as they swell and distort when exposed— making reinstallation nearly impossible.

    Special tools may be required for seal installation.

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