Generator cranks but does not start; controller displays E04 after several attempts.

Safety first: Turn OFF the generator and close the fuel supply valve. Do not smoke or create sparks near fuel. Work in a well‑ventilated area.

• Verify fuel level: Check the fuel gauge or tank level. For LP or natural gas standby units, verify the gas supply is turned on at the main shutoff and that the tank is not empty.
• Inspect fuel shutoff valve: Ensure the manual fuel shutoff valve at the generator is fully open. Some DuroStar models have an inline valve near the carburetor or fuel rail.
• Check fuel filter: Locate the inline fuel filter. If it appears dirty or restricted, replace it with a DuroStar‑specified filter. Ensure the arrow on the filter points toward the engine.
• Prime the system (if equipped): Use the manual primer bulb or priming function to remove air from the fuel line. For diesel units, open the bleed screw on the fuel filter housing and pump until fuel flows without bubbles, then tighten.
• Test fuel pump: Turn the key to ON (without cranking) and listen for the electric fuel pump. If silent, check the fuel pump fuse and relay. Use a multimeter to verify power at the pump connector. Replace the fuel pump if it does not run with proper voltage applied.
• Attempt restart: After confirming fuel supply and filter condition, attempt a manual start. If E04 persists, further diagnosis of the carburetor or fuel injection system by a technician is recommended.