Cummins/Onan — Injection Nozzle Adjustment
Adjustments
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Before you start
- Do not disturb the injector pressure adjusting screw; it cannot be reset without proper equipment.
- Keep hands away from a spraying nozzle; discharge pressure can penetrate the skin.
Procedure
- Remove each nozzle from the engine and remove the cap nut over the adjusting screw.
- Install the nozzle on a static fuel nozzle testing fixture.
- Adjust the opening pressure to 1750 psi (12,075 kPa) by turning the adjusting screw.
- Clockwise increases pressure and counterclockwise decreases it.
- Do not adjust pressure without a testing fixture.
Tools required
- Static fuel nozzle testing fixture Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Opening pressure 1750 psi (12,075 kPa)
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.