Fuel System - Onan NHC Series Operator's/Service Manual And Parts Catalog

FUEL SYSTEM
GASOLINE CARBURETOR
For correction of problems traced to,the, gasoline
carburetor, use the appropriate procedures selected
from the following sequence, referring to Figures 13
and 14.
Adjustment Under Load: Adjust the carburetor as
follows when a full load can be applied.
1. Make sure the ignition system is working properly
and that the governor is adjusted.
2. Start the engine and allow it to warm up. If the
carburetor is so far out of adjustment that the
engine will not start, close both needle valves
gently to their seats. Then open each 1 to 1-1/2
turns, first the idle and then the main adjustment.
3. With no load applied to engine, turn the idle
adjustment out until the engine speed drops
slightly below normal. Then turn the needle in
until the engine speed returns to normal.
4. Apply a full load to the engine and then carefully
turn the main adjustment in until the speed drops
slightly below normal. Turn the needle out until
the engine speed retums to normal.
Adjustment Under "No Load" Conditions: When a
T H R O T T L E
S T O P S C R E W
F U E L I D L E
A D J U S T M E N T
A
F L O A T B O W L N U T
M A I N F U E L
A D J U S T M E N T
B
F I G U R E 14. C A R B U R E T O R A D J U S T M E N T S
load cannot be applied, adjust the carburetor as
follows: .
1. Perform steps 1 and 2 as given under Adjustment
Under Load.
2. Pull out on the governor mechanism to slow the
unit down to about 800 to 900 rpm.
I D L E
A D J U S T M E N T N E E D L E -
C H O K E S H A F T
T H R O T T L E P L A T E
T H R O T T L E S H A F T
A N D L E V E R
C H O K E P L A T E
F L O A T
A S S E M B L Y
F U E L B O W L
- M A I N J E T
A D J U S T M E N T
F L O A T A X L E
^ S P R I N G
P O S I T I O N H O O K
U N D E R T A N G O N
F L O A T
P O S I T I O N O F S P R I N G
A F T E R I N S T A L L A T I O N
EH
F I G U R E 13. C A R B U R E T O R A S S E M B L Y
16