Why generators show "engine cranks but will not start": 12 documented causes and brand-specific fixes, compiled across 8 manufacturers.
Empty fuel tank, Fuel shutoff valve closed, Dirt or water in the fuel system, Clogged fuel line, Spark plug lead disconnected, Key switch or kill switch in “off” position, Faulty spark plug, Faulty ignition module
1 brandNo fuel.
1 brand- Generac: Replenish fuel / turn on fuel valve.; Verify
Improper fuel delivery to the unit Fuel supply shut off Fuel tank empty Air in the fuel system Engine fuel solenoid has not opened Defective fuel pump Defective fuel solenoid Defective engine harness Improper battery voltage to fuel pump or fuel solenoid Fuel filter dirty Low voltage from battery to fuel solenoid
1 brandEmpty fuel tank. Fuel shut-off valve closed. Poor fuel, dirt or water in the fuel system. Clogged fuel line. Spark plug lead(s) disconnected. Key switch or kill switch in “off” position. Faulty spark plugs. Faulty ignition module(s). SMART-SPARK™ malfunction (applicable models). Carburetor solenoid malfunction. Diode in wiring harness failed in open circuit mode. Vacuum fuel pump malfunction, or oil in vacuum hose. Vacuum hose to fuel pump leaking/cracked. Battery connected backwards.
1 brandOut of LP fuel.
1 brand- Generac: Replenish LP fuel. Turn on fuel shutoff valve.
. Defective main circuit board (5-4). . Foil burnt (5-5). . Defective choke. . In line fuse to ignition coil blown.
1 brandNo fuel Low oil level Emergency shutdown switch is ON Air in fuel system
1 brand- Generac: Verify there is no fuel leakage and replenish oil to full Turn emergency shutdown switch OFF Bleed air
No fuel. Insufficient oil level. PAS is ON. Air in fuel system. Clogged fuel filter. Gelled fuel. Injection pump failure. Electromagnetic type fuel pump failure. Engine control system failure.
1 brand- Generac: Verify there is no fuel leakage and replenish. Replenish oil to full. Turn PAS to OFF. See Resetting the PAS. Purge air from fuel system. Remove water and change element. Warm fuel pipes with hot water or wait until ambient temperature rises. Contact a GMP ASD.
Refer to engine manual or contact Generac Mobile Products Technical Service.
1 brandImproper fuel delivery to the unit Fuel supply shut off Fuel tank empty Air in the fuel system Engine fuel solenoid has not opened Defective fuel pump Defective fuel solenoid Defective engine harness Improper battery voltage to fuel pump or fuel solenoid
1 brandImproper fuel delivery to the unit
1 brandCommon questions
What causes engine cranks but will not start?
Common causes, most-reported first: Fau; Empty fuel tank, Fuel shutoff valve closed, Dirt or water in the fuel system, Clogged fuel line, Spark plug lead disconnected, Key switch or kill switch in “off” position, Faulty spark plug, Faulty ignition module; No fuel.; Improper fuel delivery to the unit Fuel supply shut off Fuel tank empty Air in the fuel system Engine fuel solenoid has not opened Defective fuel pump Defective fuel solenoid Defective engine harness Improper battery voltage to fuel pump or fuel solenoid Fuel filter dirty Low voltage from battery to fuel solenoid; Empty fuel tank. Fuel shut-off valve closed. Poor fuel, dirt or water in the fuel system. Clogged fuel line. Spark plug lead(s) disconnected. Key switch or kill switch in “off” position. Faulty spark plugs. Faulty ignition module(s). SMART-SPARK™ malfunction (applicable models). Carburetor solenoid malfunction. Diode in wiring harness failed in open circuit mode. Vacuum fuel pump malfunction, or oil in vacuum hose. Vacuum hose to fuel pump leaking/cracked. Battery connected backwards.; Out of LP fuel..