VESPA LX 150 4T Euro 3 Service Station Manual page 36

Troubleshooting
Possible Cause
Start-up enabling buttons failure
Carburettor nozzles clogged or dirty
Air filter obstructed or dirty.
Fuel pump fault
Excessive oil consumption/Exhaust smoke
EXCESSIVE OIL CONSUMPTION/SMOKY EXHAUST
Possible Cause
Worn valve guides
Worn valve oil guard
Oil leaks from the couplings or from the gaskets
Worn or broken piston rings or piston rings that have not been
fitted properly
Insufficient lubrication pressure
Possible Cause
By-Pass remains open
Oil pump with excessive clearance
Oil filter too dirty
Oil level too low
Engine tends to cut-off at full throttle
THE ENGINE TENDS TO STOP AT MAXIMUM THROTTLE
Possible Cause
Maximum jet clogged
Water or condensation in the carburettor chamber
Level in chamber too low
Engine tends to cut-off at idle
Possible Cause
Incorrect idle adjustment
Incorrect timing
The starter remains on
Faulty spark plug or incorrect ignition advance
Pressure too low at the end of compression
Minimum nozzle dirty
TROUBL - 36
POOR LUBRICATION PRESSURE
THE ENGINE TENDS TO STOP AT IDLE SPEED
Vespa LX 125 - 150 4T Euro 3
Operation
Check continuity using an Ohm meter, with the switch pressed;
replace if necessary
Dismantle, wash with solvent and dry with compressed air
Remove the sponge, wash with water and car shampoo, then
soak it in a mixture of 50% petrol and 50% specific oil. Press
with your hand without squeezing, allow it to drip dry and refit.
Check the pump control device
Operation
Check and replace the head unit if required
Replace the valve oil seal
Check and replace the gaskets or restore the coupling seal
Replace the piston cylinder unit or just the piston rings
Operation
Check the By-Pass and replace if required. Carefully clean the
By-Pass area.
Perform the dimensional checks on the oil pump components
Replace the cartridge filter
Restore the level adding the recommended oil type
Operation
Remove the carburettor, wash with solvent and dry with com-
pressed air
Remove the tank, wash with solvent and dry with compressed
Restore the level in the chamber by bending on the float the
thrusting reed of the petrol intake rod so as to have the float
parallel to the chamber level with the carburettor inverted.
Operation
Adjust using the rpm indicator
Time the system and check the timing system components
Check: electric wiring, circuit not interrupted, mechanical
movement and power supply; replace if necessary
Replace the spark plug or check the ignition circuit components
Check the thermal group seals and replace worn components
Wash the nozzle with solvent and dry with compressed air
air