Cummins/Onan — Fuel Pump Flow Test (Gasoline EFI)
Testing & diagnosis · Fuel system
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan HGJAA, Cummins/Onan HGJAB, Cummins/Onan HGJAD, Cummins/Onan HGJAE
Before you start
- Gasoline is flammable and explosive and can cause severe personal injury or death.
Procedure
- Disconnect the fuel return line between generator set and supply tank, ready to collect fuel.
- Prime the generator set for exactly one minute.
- Fuel flow should be approximately 1 quart (0.9 liter) per minute and pressure approximately 45 psi.
- Reconnect the fuel return line.
Tools required
- Gallon container Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Fuel flow ~1 quart (0.9 l) per minute
- Fuel pressure ~45 psi
Full service-parts list: Cummins/Onan HGJAA →, Cummins/Onan HGJAB →, Cummins/Onan HGJAD →
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.