Suzuki DF150 Service Manual page 123

3-64 ENGINE CONTROL SYSTEM
VACUUM PASSAGE INSPECTION
1. Disconnect vacuum hose 1 from vacuum switching valve
2.
2. Start engine and run it at idle speed.
Place a finger over vacuum hose end 1 and engine vacuum
is present.
3. If vacuum is not present, clean vacuum passage with com-
pressed air, start engine and check again for vacuum.
CHECK VALVE
Inspection
1. Remove check valve 1.
2. Blow air (moderate pressure) through hose fitting on white
side of check valve. Air should not pass through valve from
intake manifold (white side 3) to green side 2.
3. Blow air (low pressure) through hose fitting on green side of
check valve. Air should pass through to white side.
4. If air passes through valve in Step 2 or high pressure is
required to cause air to pass in Step 3, replace check valve.
"
DO NOT SUCK air through check valve.
Fuel vapor inside the valve is harmful.
5. Install check valve.
NOTE:
The check valve is directional. Refer to the figure for correct
installation.
4 To vacuum tank
5 From intake manifold assembly
Vacuum tank