Exhaust Emission Control System
Carburetor
1. Remove vacuum hose (green stripe) from carburetor
and connect a hand pump to the vacuum hose.
2. Plug nipple that vacuum hose was removed from.
3. Perform this test with the engine cold, then again
when hot. Apply vacuum to vacuum hose with the en
gine idling.
When engine is cold
Coolant temperature 60�C (140�F) or less:
Hand vacuum
Normal condition
pump
Engine
Vacuum applied
No change
Workman 3000/4000 Series
EGR valve
Thermo valve
Figure 55
Vacuum hose
(Green stripe)
Vacuum
Vacuum leak
Page 3 – 37
Figure 56
Liquid Cooled Gas Engine