Cummins/Onan — Test fuel pump pressure
Testing & diagnosis
From a Cummins/Onan service manual covering: 10MJC, 15MJC, 3MJA, 4MJA, 5MJB, 705MJB. Check it applies to your exact model before use.
Browse Cummins/Onan generators & specs →
Procedure
- Disconnect pump outlet line.
- Install pressure gauge.
- Operate priming lever a few times.
- Run engine at governed speed.
- Read pressure; should be 2-3 psi with gauge 16 in. above pump.
Tools required
- pressure gauge Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 2-3 psi with gauge 16 in. above pump
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.