Why generators show "engine cranks but does not start": 33 documented causes and brand-specific fixes, compiled across 13 manufacturers.
Out of fuel
4 brands- Anking: Check fuel level, add fuel if necessary
- DynaGen: Check fuel level, add fuel if necessary
- DynaGen Technologies: Check fuel level, add fuel if necessary
- GSC: Check fuel level, add fuel if necessary
Incorrect fuel, K14 fuel solenoid issue, switch S11 or heater relay issue
2 brands- Cummins/Onan: Check fuel system: fuel tank level, shut-off valves, fuel lines and connections, fuel filters, fuel pump and injection pump. Check B+ circuit through S11. Test S11 per Checkout [G]. Test K14 per Checkout [F]. Check switch S11 per Checkout [G]. Check heater relay per Checkout [E]. Check heater wiring.
- Doosan: Check fuel system: fuel tank level, shut-off valves, fuel lines and connections, fuel filters, fuel pump and injection pump. Check B+ circuit through S11. Test S11 per Checkout [G]. Test K14 per Checkout [F]. Check switch S11 per Checkout [G]. Check heater relay per Checkout [E]. Check heater wiring.
Restricted fuel supply due to: a. Fuel level below pickup tube in tank. b. Fuel filter clogged. c. Fuel injectors clogged
2 brands- Cummins/Onan: 1a. Add fuel if low. Prime the fuel system. 1b. Replace clogged fuel filter and check fuel supply for contamination. 1c. Refer to engine service manual. 2a. Check wiring continuity of fuel solenoid circuit, refer to Figure 4-6. 2b. Test fuel solenoid. 3a. Check wiring continuity of fuel pump circuit, refer to Figure 4-6. 3b. Test fuel pump. 3c. Measure voltage to fuel pump with start switch held in the Start position. If voltage is not present and fuel pump circuit checks ok, control assembly (A1) is defective.
- Kubota: 1a. Add fuel if low. Prime the fuel system. 1b. Replace clogged fuel filter and check fuel supply for contamination. 1c. Refer to engine service manual. 2a. Check wiring continuity of fuel solenoid circuit, refer to Figure 4-6. 2b. Test fuel solenoid. 3a. Check wiring continuity of fuel pump circuit, refer to Figure 4-6. 3b. Test fuel pump. 3c. Measure voltage to fuel pump with start switch held in the Start position. If voltage is not present and fuel pump circuit checks ok, control assembly (A1) is defective.
Fuel solenoid (K4) open due to: a. Open in fuel solenoid circuit. b. Defective fuel solenoid
2 brands- Cummins/Onan: 1a. Add fuel if low. Prime the fuel system. 1b. Replace clogged fuel filter and check fuel supply for contamination. 1c. Refer to engine service manual. 2a. Check wiring continuity of fuel solenoid circuit, refer to Figure 4-6. 2b. Test fuel solenoid. 3a. Check wiring continuity of fuel pump circuit, refer to Figure 4-6. 3b. Test fuel pump. 3c. Measure voltage to fuel pump with start switch held in the Start position. If voltage is not present and fuel pump circuit checks ok, control assembly (A1) is defective.
- Kubota: 1a. Add fuel if low. Prime the fuel system. 1b. Replace clogged fuel filter and check fuel supply for contamination. 1c. Refer to engine service manual. 2a. Check wiring continuity of fuel solenoid circuit, refer to Figure 4-6. 2b. Test fuel solenoid. 3a. Check wiring continuity of fuel pump circuit, refer to Figure 4-6. 3b. Test fuel pump. 3c. Measure voltage to fuel pump with start switch held in the Start position. If voltage is not present and fuel pump circuit checks ok, control assembly (A1) is defective.
Fuel pump (E1) not working due to: a. Open in fuel pump circuit. b. Defective fuel pump. c. Defective control assembly (A1) Start switch held in the Start position
2 brands- Cummins/Onan: 1a. Add fuel if low. Prime the fuel system. 1b. Replace clogged fuel filter and check fuel supply for contamination. 1c. Refer to engine service manual. 2a. Check wiring continuity of fuel solenoid circuit, refer to Figure 4-6. 2b. Test fuel solenoid. 3a. Check wiring continuity of fuel pump circuit, refer to Figure 4-6. 3b. Test fuel pump. 3c. Measure voltage to fuel pump with start switch held in the Start position. If voltage is not present and fuel pump circuit checks ok, control assembly (A1) is defective.
- Kubota: 1a. Add fuel if low. Prime the fuel system. 1b. Replace clogged fuel filter and check fuel supply for contamination. 1c. Refer to engine service manual. 2a. Check wiring continuity of fuel solenoid circuit, refer to Figure 4-6. 2b. Test fuel solenoid. 3a. Check wiring continuity of fuel pump circuit, refer to Figure 4-6. 3b. Test fuel pump. 3c. Measure voltage to fuel pump with start switch held in the Start position. If voltage is not present and fuel pump circuit checks ok, control assembly (A1) is defective.
Fuel solenoid and related wiring, Electric choke components and wiring (if used), Spark at the spark plug, Fuel pump OK, Fuel pulsate from line removed at carburetor (Gasoline sets.), Fuel supply system: fuel tank, shutoff valves, fuel lines and connections, fuel filters and pumps
1 brand- archive.org: Check fuel solenoid and related wiring. Repair or replace as needed. Check electric choke components and wiring (if used). Adjust per Operator’s Manual instructions. Is there a spark at the spark plug? Check ignition wiring and components. Is fuel pump OK? Does fuel pulsate from line removed at carburetor? (Gasoline sets.) Refer to Engine Service Manual. Check fuel supply system: fuel tank, shutoff valves, fuel lines and connections, fuel filters and pumps.
Restricted fuel supply due to: a. Closed shutoff valve in supply line. b. Engine is not getting fuel
1 brand- Orion: 1a. Open any closed shutoff valve in the fuel line supplying the engine. 1b. Fill the main fuel supply tank if the set is gasoline or propane fueled, for natural gas fueled sets, check with the gas utility. 2. Service according to the engine service manual. 3a. Test solenoid K11 and wiring. 3b. Test run relay K12 and wiring. 4a. Check wiring continuity of fuel solenoid circuit. 4b. Test fuel solenoid. 5a. Check wiring continuity of fuel tank solenoid circuit. 5b. Test fuel tank solenoid.
The engine ignition system is malfunctioning (ignition coil, distributor, spark plugs, high tension spark plug and coil cables and timing)
1 brand- Orion: 1a. Open any closed shutoff valve in the fuel line supplying the engine. 1b. Fill the main fuel supply tank if the set is gasoline or propane fueled, for natural gas fueled sets, check with the gas utility. 2. Service according to the engine service manual. 3a. Test solenoid K11 and wiring. 3b. Test run relay K12 and wiring. 4a. Check wiring continuity of fuel solenoid circuit. 4b. Test fuel solenoid. 5a. Check wiring continuity of fuel tank solenoid circuit. 5b. Test fuel tank solenoid.
Run relay (K12) not energized due to: a. Defective start solenoid (K11). b. Defective run relay (K12)
1 brand- Orion: 1a. Open any closed shutoff valve in the fuel line supplying the engine. 1b. Fill the main fuel supply tank if the set is gasoline or propane fueled, for natural gas fueled sets, check with the gas utility. 2. Service according to the engine service manual. 3a. Test solenoid K11 and wiring. 3b. Test run relay K12 and wiring. 4a. Check wiring continuity of fuel solenoid circuit. 4b. Test fuel solenoid. 5a. Check wiring continuity of fuel tank solenoid circuit. 5b. Test fuel tank solenoid.
Optional fuel solenoid (K1) not energized due to: a. Open in fuel solenoid circuit. b. Defective fuel solenoid
1 brand- Orion: 1a. Open any closed shutoff valve in the fuel line supplying the engine. 1b. Fill the main fuel supply tank if the set is gasoline or propane fueled, for natural gas fueled sets, check with the gas utility. 2. Service according to the engine service manual. 3a. Test solenoid K11 and wiring. 3b. Test run relay K12 and wiring. 4a. Check wiring continuity of fuel solenoid circuit. 4b. Test fuel solenoid. 5a. Check wiring continuity of fuel tank solenoid circuit. 5b. Test fuel tank solenoid.
Optional fuel tank solenoid (K2) not energized due to: a. Open in fuel tank solenoid circuit. b. Defective fuel tank solenoid
1 brand- Orion: 1a. Open any closed shutoff valve in the fuel line supplying the engine. 1b. Fill the main fuel supply tank if the set is gasoline or propane fueled, for natural gas fueled sets, check with the gas utility. 2. Service according to the engine service manual. 3a. Test solenoid K11 and wiring. 3b. Test run relay K12 and wiring. 4a. Check wiring continuity of fuel solenoid circuit. 4b. Test fuel solenoid. 5a. Check wiring continuity of fuel tank solenoid circuit. 5b. Test fuel tank solenoid.
Incorrect fuel? See Operator’s Manual recommendations. Check fuel system: fuel tank level, shut-off valves, fuel lines and connections, fuel filters, fuel pump and injection pump. Okay? Does K14 fuel solenoid energize when S11 is in Start position?
1 brand- Cummins/Onan: Check B+ circuit through S11. Test S11 per Checkout [G]. Test K14 per Checkout [F]. Check switch S11 per Checkout [G]. Check heater relay per Checkout [E]. Check heater wiring.
Possible Cause/Diagnosis/Repair
1 brand- Cummins/Onan: 1. Clear the Gen Wait message from the Operator Panel by cycling it off and on. Try starting again. 2. Check the fuel level and fill as necessary. 3. Press the stop switch (p. 2-2) if it is not in its “1” position. 4. Replace the fuel if it is not of the specified grade or suitable for the ambient temperature (p 2-1). 5. Check Fuel flow from lift pump, should be approximately 0.4 pints/minute (200 ml/minute). Look for kinked hoses and replace fuel filter as need. 6. Verify that the fuel solenoid is getting 12V DC and clicks open when energized. 7. The cam to crank timing is off. Check Timing. Refer to Engine Workshop Manual 983−0504. 8. Valves not set properly: Check Valve lash. Refer to Engine Workshop Manual 983−0504. 9. The injector nozzle is blocked or locked. Remove the injector and check popping pressure and spray pattern. Refer to Engine Workshop Manual 983−0504. 10. The injection pump is stuck. Remove the high pressure injector line and crank the engine. Watch for fuel at delivery valve. Refer to Engine Workshop Manual 983−0504 11. Engine compression is low—blown head gasket, bad injector seal, worn engine. Refer to Engine Workshop Manual 983−0504.
Fuel tank empty.
1 brand- Aggreko: Fill up fuel tank.
4a. Check continuity between starter lead on start solenoid (S1) and ground. a. Open circuit to starter (B1). b. Open circuit between battery (B+) and the start solenoid contact (BAT). c. Defective start solenoid (K1). 4b. Measure voltage between starter terminal and ground with switch (S1) held in the Start position. If voltage is not present and continuity checks OK, start solenoid (K1) is defective. 4c. If voltage is present in step 4b, starter (B1) is defective.
1 brandCommon questions
What causes engine cranks but does not start?
Common causes, most-reported first: Out of fuel; Incorrect fuel, K14 fuel solenoid issue, switch S11 or heater relay issue; Restricted fuel supply due to: a. Fuel level below pickup tube in tank. b. Fuel filter clogged. c. Fuel injectors clogged; Fuel solenoid (K4) open due to: a. Open in fuel solenoid circuit. b. Defective fuel solenoid; Fuel pump (E1) not working due to: a. Open in fuel pump circuit. b. Defective fuel pump. c. Defective control assembly (A1) Start switch held in the Start position; Fuel solenoid and related wiring, Electric choke components and wiring (if used), Spark at the spark plug, Fuel pump OK, Fuel pulsate from line removed at carburetor (Gasoline sets.), Fuel supply system: fuel tank, shutoff valves, fuel lines and connections, fuel filters and pumps.