Section 3 Troubleshooting When troubles occur, be sure to check the simple causes which, at first, may seem too obvious to be considered. For example, a starting problem could be caused by an empty fuel tank. 1. PTO drive is engaged. 2. Dirt or water in the fuel system. 3. Clogged fuel line. 4. Loose or faulty wires or connections. 5. Faulty or misadjusted choke or throttle controls. 6. Faulty spark plugs. 7. Low compression. 8. Weak spark. 9. Fuel pump malfunction causing lack of fuel. 10. Engine overheated-cooling system problem. 11. Quality of fuel. 12. Flywheel key sheared. 13. Intake system leak. Some common causes of engine troubles are listed below.
Use these to locate the causing factors. Engine Cranks But Will Not Start 1. Empty fuel tank. 2. Fuel shut-off valve closed. 3. Dirt or water in the fuel system. 4. Clogged fuel line. 5. Spark plug lead(s) disconnected. 6. Key switch or kill switch in “off” position. 7. Faulty spark plugs. 8. Faulty ignition module(s). 9. Carburetor solenoid malfunction. 10. Diode in wiring harness failed in open circuit mode. 11. Vacuum fuel pump malfunction, or oil in vacuum hose. 12. Vacuum hose to fuel pump leaking/cracked. 13. Battery connected backwards. 14. Safety interlock system engaged. Engine Will Not Crank 1. PTO drive is engaged. 2. Battery is discharged. 3. Safety interlock switch is engaged.
4. Loose or faulty wires or connections. 5. Faulty key switch or ignition switch. 6. Faulty electric starter or solenoid. 7. Seized internal engine components. Engine Runs But Misses 1. Dirt or water in the fuel system. 2. Spark plug lead disconnected. 3. Loose wires or connections that intermittently short the kill circuit of ignition system to ground. 4. Engine overheated-cooling system problem. 5. Faulty ignition module. 6. Faulty spark plugs. 7. Carburetor adjusted incorrectly. 8. Faulty interlock switch. Engine Starts But Does Not Keep Running 1. Restricted fuel tank cap vent. 2. Poor fuel, dirt or water in the fuel system. 3. Faulty/misadjusted choke or throttle controls. 4.
Loose wires or connections that short the kill terminal of ignition module to ground. 5. Faulty cylinder head gasket. 6. Faulty carburetor. 7. Vacuum fuel pump malfunction, or oil in vacuum hose. 8. Leaking/cracked vacuum hose to fuel pump. 9. Intake system leak. 10. Diode in wiring harness failed in open circuit mode. Engine Will Not Idle 1. Restricted fuel tank cap vent. 2. Dirt or water in the fuel system. 3. Faulty spark plugs. 4. Idle speed (RPM) adjusting screw improperly set. 5. Low compression. 6. Stale fuel and/or gum in carburetor. 7. Fuel supply inadequate. 8. Engine overheated-cooling system problem. 3.1 Section 3 Troubleshooting 3 Troubleshooting Guide Engines Starts Hard