50
Failure diagnosis
Hard staring or starting failure of engine Bad performance when engine is in high speed
Insufficient engine power Abnormal sound of engine
Bad performance when engine is in low speed or idling
Hard starting or starting failure of engine
Diagnosis
Cause
1. Check if fuel entered carburetor
→No fuel in carburetor→ 1. No fuel in fuel tank
Already in carburetor 2. Fuel switch blocked
3. Fuel tube blocked
4. Float needle of carburetor seized up
2. Remove and check spark plug
→Weak or no spark→ 1. Dirty or damaged spark plug
Normal spark 2. Magneto failure
3. Ignition switch failure
4
、
Sensor failure
5
、
Igniter failure
6
、
Ignition coil failure
7
、
High voltage wire failure
8
、
Break or short circuit of power
source
3.
Check cylinder pressure
→Low pressure
→
1.Starting device skidding and engine starting failure
Normal pressure
2. Narrow valve clearance or no clearance
3. Distortion of guiding rod of valve
4. Poor matching between cylinder seat and valve
5. Abrasion on cylinder and piston ring
6. Poor sealing performance of gasket of cylinder head
7. Incorrect installation
8. Wrong timing of gas distribution
4. Restart engine
→Ignited but staring failed→ 1. Excessively opened throttle gate
Engine starting failed 2. Leakage of air intake tube
3. Wrong timing of ignition
5. Remove spark plug
→Wet spark plug→ 1
、
Fuel rich in carburetor
Dry spark plug 2
、
Excessively opened throttle
6
、
Turn off choke, and restart engine
Insufficient engine power
Diagnosis
Cause
1
、
Accelerate from idling to high speed
→No speed change→ 1
、
Clutch skidding
Normal speed 2
、
Clutch abrasion