Engine Overheats; Surges Or Runs Unevenly; Engine Misfires - Tecumseh ECV100-120 - TECHNICIAN S Handbook

TESTING
ENGINE KNOCKS
1. Check the blade hub, blade adapter, or crankshaft coupler for loose fit, loose bolts, or crankshaft key damage.
Remove, inspect, replace if necessary. Reinstall and re-torque the bolts to the proper torque.
2. Check the flywheel key and the flywheel and crankshaft keyway for wear or partial shearing. Replace if any
damage is evident. Tighten the flywheel nut to the proper torque.
3. Check for the correct ignition module air gap or the correct timing (point ignition). Replace the points and condenser
if the points show any wear, oil, or pitting.
4. Remove the cylinder head and check for excessive carbon in the combustion chamber. Also check for the correct
head gasket used, and check the spark plug for proper reach and heat range (correct spark plug for the engine).
5. Check for the proper valve lash using a feeler gauge, and check the internal components (piston, cylinder, connecting
rod, crankshaft journal) for excessive clearance.

ENGINE OVERHEATS

1. Make sure the engine is not being overloaded. Remove excess load (sharpen blades, limit operation speed,
process less material).
2. Check the oil level and viscosity. Add or replace as necessary.
3. Check for clogged cooling fins or obstructions to the air flow. Remove the blower housing, clean and reinstall.
4. Check the carburetor for correct adjustment or remove and clean the carburetor using tag wire and compressed
air. See Chapter 3 under "Service."
5. Check the engine R.P.M. setting using a vibratach or other tachometer and compare it to the R.P.M. settings found
on microfiche card #30 according to the engine model and specification number. Adjust as necessary.
6. Make sure the correct spark plug is being used. Check the ignition timing. See Chapter 8 "Ignition - Service."
Correct flywheel key or partially sheared key.
7. Remove the cylinder head to check for excessive carbon buildup. Clean as necessary.

SURGES OR RUNS UNEVENLY

1. Check the fuel cap to make sure it is venting. Loosen the cap and retry engine operation.
2. Replace or clean the air filter.
3. Check the carburetor adjustment or clean the carburetor. See Chapter 3 under "Service."
4. Check the engine R.P.M. setting using a vibratach or other tachometer and compare it to the R.P.M. settings found
on microfiche card #30 according to the engine model and specification number. Adjust as necessary.
5. Visually check all linkages. Check the governor shaft, throttle shaft, or pivot points for binding.
6. Check the ignition module operation using a gap type tester inserted in the high tension lead. Check for intermittent
spark, incorrect spark plug, or a fouled condition.

ENGINE MISFIRES

1. Check the spark plug for the proper application or a fouled condition. Replace if questionable.
2. Reset the carburetor following the adjustment procedure or clean the carburetor. See Chapter 3 under "Service."
3. Check the ignition timing. See Chapter 8 under "Service."
4. Check for carbon buildup in the combustion chamber.
5. Inspect the valves and valve seats for leakage. Check for scoring or discoloration on the valve stem in the valve
guide area. Recut the valves and seats if questionable. See "Valve Service" in this chapter.
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