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ENGINE: FUEL SYSTEM
91
TROUBLE
DIAGNOSIS
GUIDE
When the incorrect operation of engine has been
definitely traced to a defective carburetion, any
other possible condition having been checked and
discarded, look for the origin of the trouble among
the following:
- Flooded carburetor: valve needle seated im-
properly.
-
Engine will not start when cold:
clogged
start-
ing jet or shortened starting device control travel.
- Engine will not start when warm: clogged
jets or passages, misadjusted idle speed circuit.
-
Engine will not idle: clogged jets or passages,
misadjusted idle speed circuit.
-
Engine pick up is poor: clogged main jet or
emulsion orifices.
- Increased fuel consumption: foreign matter in
emulsion well orifices.
IDLING
ADJUSTMENT
On this carburetor the adjustment is by means
of the throttle stop screw (56, figs. 152 and 153)
and the volume control screw (30). Screw (56) con-
trols the degree of opening of the throttle valve.
while the tapered screw (30) regulates the volume
of mixture delivered by the idling mixture passage
and further mixed with the air drawn in
by
engine
suction through the reduced gaps between the main
barrel
wall
and the throttle valve when the latter is
in
the idling position, thus enabling the appropriate
Fig. 152 - View of Weber carburetor from idle setscrews end.
4. Idle jet
holdel. -
7. Strainer inspection plug. - 9. Fuel in lei con-
nector. - 15. Main jet holder.• 30. Volume control screw. - 55. Vac-
uum advance connector. - 56. Throttle slop screw.
degree of idling richness to be obtained.
Idling adjustment should be carried out with the
engine warm and running
by
first of
all
adjusting
the throttle stop screw (56) to a point where the
engine does not falter and then adjusting the volume
control screw (30) to obtain the mixture which gives
the highest regular engine speed at the selected
degree of throttle restriction. Finally, further narrow
the throttle opening to the best idle speed and con-
trol the rate of the mixture with the screw (30).
Fig. 153 • View of Solex carburetor from idle setscrews end.
4. Idle jet holder. - 7. Slrainer Inspection plug•• 9. Fuel inlet con-
nector. - 15. Main jet holder. - 30. Volume cOntrol screw. - 39. Power
pump control lever. - 43. Power pump. - 55. Vacuum advance con-
nector. - 56. Throttle stop screw. - 57. Venturi mounting screw.
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