Inspection/Adjustment; Troubleshooting - KYMCO NEXXON 50 Service Manual

1
. GENERAL INFORMATION

TROUBLESHOOTING

ENGINE WILL NOT START OR IS HARD TO START

Inspection/Adjustment

Check if fuel reaches
carburetor by loosening
drain screw
Remove spark plug and
install it into spark plug
cap to test spark by
connecting it to engine
ground
Test cylinder
compression
Start engine by follow-
ing normal starting
procedure
Remove spark plug and
inspect again
1-17
Symptom
Fuel reaches
carburetor
Spark jumps
Normal
compression
Engine does not
fire
Dry spark plug
Fuel does not
reach carburetor
Weak or no spark
Low or no
compression
Engine fires but
does not start
Wet spark plug
NEXXON 50
Probable Cause
Empty fuel tank
Clogged carburetor fuel inlet
tube, vacuum tube or fuel tube
Clogged float oil passage
Clogged fuel filter
Clogged charcoal canister
Clogged auto fuel valve strainer
Faulty valve passage
Faulty fuel pump
Faulty spark plug
Fouled spark plug
Faulty CDI unit
Faulty pulser coil
Faulty exciter coil
Faulty ignition switch
Broken or shorted ignition coil
wire
Faulty or slipping clutch
Valve clearance too small
Valve stuck open
Worn cylinder and piston rings
Leaking cylinder head gasket
Faulty choke control system
Leaking intake manifold
Incorrect ignition timing
Incorrectly adjusted air screw
Flooded carburetor
Throttle valve excessively open
Clogged air cleaner