Troubleshooting - Sym DD 50 Service Manual

Troubleshooting

A. Engine hard to start or can not be started
Check and adjustment
Loosen carburetor drain bolt
to check if there is gasoline
inside the carburetor
Fuel supplied tom
carburetor sufficient
Remove spark plug, install
it into spark plug cap, and
perform a spark test
against engine ground.
Check if sparks
Perform cylinder
compression pressure test.
cylinder compression pressure normal
Re-start by following the
starting procedures
No ignition
Remove the spark plug
again and check it.
Dry spark plug
Remove carburetor after 30
minutes and connect a hose
onto fuel supplement circuit.
Then blow the hose with air
Blowing in normal
This chapter Contents
Fault condition
No fuel is supplied to
carburetor
Week sparks or no spark
at all
Low compression
pressure or no pressure
There are some signs of
ignition, but engine can
not be started
Wet spark plug
Blowing clogged
1. GENERAL INFORMATION
Probable causes
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
6. Crankcase leakage for pre-compression
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 auto-starter
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