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Engine cranks but will not start

Why generators show "engine cranks but will not start": 26 documented causes and brand-specific fixes, compiled across 9 manufacturers.

Fau

2 brands

Incorrect starting procedure, No fuel, Exhaust restricted, Fuel filter plugged or full of water, Injection pump not getting fuel or air in fuel system, Faulty injection pump or nozzles

2 brands
  • Doosan: Verify correct starting procedure, Check fuel in tank and manual shut-off valve, Check and correct exhaust restriction, Replace fuel filter or drain water from filter, Bleed fuel system, Consult authorized diesel repair station for repair or replacement
  • Ingersoll Rand: Verify correct starting procedure, Check fuel in tank and manual shut-off valve, Check and correct exhaust restriction, Replace fuel filter or drain water from filter, Bleed fuel system, Consult authorized diesel repair station for repair or replacement

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 brand

No fuel.

1 brand
  • Generac: Replenish fuel / turn on fuel shutoff valve.; Replenish fuel / turn on fuel valve.

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 brand

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.

1 brand

Out of LP fuel.

1 brand
  • Generac: Replenish LP fuel. Turn on fuel shutoff valve.

No 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 brand

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

1 brand

Improper fuel delivery to the unit

1 brand

Incorrect starting procedure.

1 brand
  • Doosan: Verify correct starting procedure.

Out of LP fuel. Faulty fuel solenoid.

1 brand
  • Generac: Replenish LP fuel. Turn on fuel shutoff valve. Contact an IASD.

1) Out of fuel. 2) Defective fuel solenoid (FS). 3) Defective spark plug(s). 4) Valve clearance needs adjustment.

1 brand
  • Generac: 1) Replenish fuel / Turn on fuel valve. 2) * 3) Clean, check gap, or replace plug(s). 4) Adjust valve clearance.; 1) Replenish fuel / Turn on fuel valve. 2) * 3) Clean, re-gap or replace plug(s). 4) Adjust valve clearance.

Affected models

Atlas Copco QAS 108Cummins/Onan HDCABCummins/Onan Not SpecifiedDoosan G100-SIIIADoosan G150-SIIIADoosan G200-SIIIADoosan G60-SIIIADoosan G80-SIIIA

Related fault codes

Atlas Copco fault codesCummins/Onan fault codesDoosan fault codesGenerac fault codesKohler fault codesWinco fault codes

Common questions

What causes engine cranks but will not start?

Common causes, most-reported first: Fau; Incorrect starting procedure, No fuel, Exhaust restricted, Fuel filter plugged or full of water, Injection pump not getting fuel or air in fuel system, Faulty injection pump or nozzles; 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..