Sym GTS 250, Service Manual

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1. General Information
1-12
Troubles Diagnosis
A. Engine hard to start or can not be started
To this chapter contents
Check and adjustment Fault condition Probable causes
Loosen carburetor drain bolt
to check if there is gasoline
inside the carburetor
Fuel supplied tom
carburetor sufficient
No fuel is supplied to
carburetor
Remove spark plug, install it
into spark plug cap, and
perform a spark test against
engine ground.
Perform cylinder
compression pressure test.
Check if sparks Weak sparks, no spark
at all
Cylinder compression
pressure normal
Low compression
pressure or no pressure
Re-start by following the
starting procedures
No ignition There are some signs of
ignition, nut engine can
not be started
Remove the spark plug again
and check it.
Remove carburetor after 30
minutes and connect a hose
onto fuel rich circuit. Then
blow the hose with air
Dry spark plug Wet spark plug
Blowing in normal Blowing clogged
1. No fuel in fuel tank
2. Check if the pipes, fuel tank to carburetor
and intake vacuum, are clogged.
3. Float valve clogged
4. Lines in fuel tank evaporation system
clogged
5. Malfunction of fuel pump
6. Loosen or damaged fuel pump vacuum
hose
7. Fuel filter clogged
1. Malfunction of spark plug
2. Spark plug foul
3. Malfunction of CDI set
4. Malfunction of AC generator
5. Ignition coil is in open or short circuit
6. Ignition coil leads open or short circuit
7. Malfunction of main switch
1. Piston ring seized
2. Malfunction of cylinder valves
3. Worn cylinder and piston ring
4. Cylinder gasket leak
5. Sand hole in compression parts
1. Malfunction of throttle valve operation
2. Air sucked into intake manifold
3. Incorrect ignition timing
1. Fuel level in carburetor too high
2. Malfunction of throttle valve operation
3. Throttle valve opening too wide
1. Malfunction of automatic by- starter