Cummins/Onan — Fuel Pump Flow Test (EFI)
Testing & diagnosis
From a Cummins/Onan service manual covering: 5.5 HGJAA, 5.5 HGJAB, 5.5 HGJAC, 5.5 HGJAD, 5.5 HGJAE, 5.5 HGJAF, 7.0 HGJAA, 7.0 HGJAB, 7.0 HGJAC, 7.0 HGJAD, 7.0 HGJAE, 7.0 HGJAF. Check it applies to your exact model before use.
Applies to: Cummins/Onan 5.5 HGJAD, Cummins/Onan 5.5 HGJAE, Cummins/Onan 7.0 HGJAD, Cummins/Onan 7.0 HGJAE
Before you start
- Gasoline is flammable and explosive
Procedure
- Disconnect the fuel return line between genset and supply tank.
- Be prepared to collect fuel in a gallon container.
- Prime the genset for exactly one minute.
- Verify flow is approximately 1 quart (0.9 liter) per minute and pressure about 45 psi.
- Reconnect the fuel return line.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Approximately 1 quart (0.9 liter) per minute
- Fuel pressure approximately 45 psi
Full service-parts list: Cummins/Onan 5.5 HGJAD →, Cummins/Onan 5.5 HGJAE →, Cummins/Onan 7.0 HGJAD →, Cummins/Onan 7.0 HGJAE →
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.