Onan NHC Series Operator's/Service Manual And Parts Catalog page 289

diaphragm out pushing tuel through thepump output
reed valve into the output chamber and into the fuel
line.
Servicing the Pulsating Diaphragm Fuel Pump
1. Remove vacuum and fuel lines. Inspect lines for
wear, cracking, etc.
2. Scribe two lines (one each on opposite ends of
pump) across pump parts. This will insure correct
alignment of pump parts with each other and
carburetor when pump is reassembled.
3. Remove fuel pump attaching screws.
4. Holding pump carefully, pull sectionsof thepump
apart. The diaphragm, plunger, return spring and
plate, pump body and gaskets will now be loose.
5. Check parts for wear and damage. Replace with
new parts where necessary.
6. The pump air bleed hole in pump base must be
unclogged to allow unrestricted movement of
pump diaphragm.
r ^ ^ ^ ^ ^ - ^ A c l o g g e d d i a p h r a g m air b l e e d h o l e c a n
L ^ ^ A ^ ^ . ^ ^ ^ i cause d i a p h r a g m w e a r a n d seal d a m a g e
w h i l e i n h i b i t i n g p u m p o p e r a t i o n .
7. Replace gaskets and reassemble pump as shown
in Figure 17.
8. Install pump and replace lines. Makesurefuel line
clamps are replaced on fuel line.
W A R N I N G \ U s e care w h e n r e a s s e m b l i n g t h e p u m p .
A l l parts m u s t b e p e i i e c t l y a l i g n e d or the
THERMO-MAGNETIC CHOKE (Optional)
This choke uses a strip heating element and a heat
sensitive bimetal spring to control the choke plate
position. In addition to this, a solenoid is actuated
during engine cranking, closing the choke all or part
way, depending on ambienttemperature. The bimetal
is factory set to position the choke to the proper
opening under any ambient condition.
Choke Adjustment: If adjustment of the bimetal is
needed, it must be made at ambient temperature. Do
not attempt adjustments until engine has been shut
down for at least one hour. Loosen the screw which
secures the choke body assembly. Refer to Figure 18.
J3 —«>
L O O S E N T H I S
SCREW A N D
R O T A T E T H E '
E N T I R E C O V E R
A S S E M B L Y
F I G U R E 18. T H E R M O - M A G N E T I C C H O K E
p u m p w i l l leak c r e a t i n g a lire h a z a r d .
S P R I N G . C H O K E - ,
L E V E R . L I M I T -,
W A S H E R
( 1 7 / 6 4 I . D . x S / 8 O . D . x l / i e ")
W A S H E R . I N S U L A T
R I N G . R E T A I N I N G
P L A T E . C H O K E
M O U N T I N G
B O D Y . C H O K E
P L A T E .
C H O K E C O V E R
C O I L . S O L E N O I D
F R A M E . S O L E N O I D
W A S H E R . S H A K E P R O O F
N U T .. __-/fS)i W A S H E R ( 2 4 / 6 4 I . D . X 9 / 1 6 O . D . X 1 / 1 6 " )
( 5 / 1 6 - 1 8 " )
L E A D , G R O U N D
F I G U R E 19. C H O K E A S S E M B L Y
20
90238S