Cummins/Onan — Injection Pump Timing - Method 1 (Calculate Button Thickness)
Adjustments
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan DJB engine
Before you start
- Pump timing is critical
Procedure
- Record port closing dimensions and button number of the old pump.
- Use the formula to calculate the new button thickness.
- Determine the button code letter from Table 1.
- Install the correct button in the pump and install the pump.
Specs & values
- Example: old pump port closing 1.109, button thickness 0.107; new pump port closing 1.216; new button 0.113 (use button C)
Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.