Cummins/Onan 20W-20 — Adjusting Injection Nozzle Opening Pressure
Adjustments
For the Cummins/Onan 20W-20, from the Cummins/Onan service manual.
Applies to: Cummins/Onan 20W-20, Cummins/Onan RDJF engine
Before you start
- Do not adjust pressure without a testing fixture.
Procedure
- Remove nozzle from the engine.
- Remove plug from center of cap nut and loosen cap nut.
- Install nozzle on a static fuel nozzle testing fixture.
- Adjust opening pressure to 1750 psi by turning adjusting screw.
- Clockwise increases pressure, counterclockwise decreases it.
Tools required
- Diesel Nozzle Tester 420-0184 Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Adjust opening pressure to 1750 psi (12,075 kPa)
Full service-parts list: Cummins/Onan 20W-20 →
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.