Firman standby generator cranks but does not start and the controller shows E03 after several attempts.
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Safety first: Turn OFF the generator and disconnect the battery negative cable. Work in a well-ventilated area away from open flames or sparks.
- Verify fuel level: Check the main fuel tank or gas line feeding the Firman standby generator. For diesel or gasoline models, ensure the tank has adequate fuel. For natural gas/propane models, verify the gas supply valve is fully open and that the utility or tank has pressure.
- Inspect fuel shutoff valves: Confirm any manual fuel shutoff valves near the generator are in the ON position.
- Replace fuel filter: Locate the inline fuel filter or cartridge filter on the Firman fuel system. Clamp the fuel line if necessary, remove the old filter, and install a new OEM-equivalent filter observing flow direction arrows.
- Check fuel pump operation: Turn the key or controller to RUN (without starting) and listen for the electric fuel pump priming (if equipped). If silent, test for 12 V at the pump connector. Replace the fuel pump if it does not run with proper voltage.
- Bleed air (diesel models): Loosen the bleed screw on the fuel filter housing or injection pump and operate the manual priming pump until fuel flows without bubbles, then retighten.
After corrections, reconnect the battery, clear the E03 code per the controller instructions, and attempt a start. If the code persists, a technician should check fuel pressure with a gauge and inspect injectors or carburetor.