Cummins/Onan — Demand Regulator Test Procedure
Testing & diagnosis
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan NHEL
Before you start
- Most parts cleaning solvents are flammable and corrosive.
Procedure
- Connect pressure gauge to test port on back of regulator.
- Connect compressed air at least 80 psi (550 kPa) to inlet opening.
- If primary valve sound, gauge reads approximately 1-1/2 psi (10.3 kPa) and holds steady.
- Close air valve and observe gauge; pressure drop indicates secondary valve seat leaking.
- Disassemble and clean regulator if it fails either test; replace if still fails.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan NHEL →
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.