Willys MB - Page 44

WILLYS MODEL "hlB" %-TON 4 x 4 GOVERNMENT TRUCIC
0300-43
FIG. 2-FUEL SYSTEM
Float Circuit or Fuel Level
The float
ciriuit Fig. 3. is important because it
controls the height of the fuel level in the bowl
and in the
nozzle. If the fuel level is too high,
it
wil1 cause trouble in the low and the high speed
circuits.
The float bowl No.
3, acts as a reservoir to hold
a supply of fuel. The
leyel of the fuel in the bowl
is controlled by a combination of parts which are:
float and lever
assembly No. 2, float bowl cover
No.
4, needle valve and seat assembly No. 1.
Low Speed Circuit
The idle or low speed circuit, Fig.
4, controls the
supply of fuel to the engine during idle and light
load speeds up to approximately 20
miles per liour,
and it feeds a smal1 amount of fuel during the
entire operation of the high speed circuit (gradu-
ally decreasing as speed is increased, above 20
m.p.h.).
During idling and Io\v speed operation of the
engine, fuel flows from the float bowl through
the idle jet No.
8. to the point where it combines
with
a stream of air coming in through the by-pass.
No.
9. The combining of the air with the fuel
atomizes or breaks up the fuel
int0 a vapor.
This mixture of air and fuel continues on
through the economizer No. 10 until it begins to
pass the point. where it is further combined with a
stream of air coming in through the lower
bleed
No. ll. This mixture of fuel and air then flows
downward to the idle port chamber and thence
into the engine at the port No. 12 and through the
idle adjusting screw seat
just below. This mix-
ture is richer than the engine requires but when
mixed with the air coming past the throttle valve
it forms a combustible mixture of the right
pro-
portion for idle speeds.
The idle port
is slotted so that as the throttle
valve is
opened it wil1 not only allow more air to
come in past it, but wil1 also uncover more of the
idle port allowing a greater quantity of fuel and
air mixture to enter the intake manifold.
FIG. 3-FLOAT CIRCUIT
FIG. 4-LOW SPEED CIRCUIT