Cummins/Onan — Fuel Pressure Test
Testing & diagnosis · fuel pump
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan NHEL
Before you start
- Do not substitute automotive fuel pump.
Procedure
- Disconnect fuel line at pump outlet.
- Connect 0-15 psi pressure gauge.
- Push Start/Stop switch to START until pressure stabilizes.
- Pressure should be 3.5-6 psi (24-41 kPa).
- Repeat with vehicle engine running.
Tools required
- pressure gauge Amazon
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.