Choke
The choke consists of a bi-metal, spiral strip, electric
heating element, and choke pulloff diaphragm. The bi-
metal coil is connected to the choke shaft and holds the
choke plate nearly closed when the engine is cold.
When the engine starts, vacuum from the intake mani-
fold causes the pulloff diaphragm to pull in and partially
open the choke. As the engine continues to run, electric
current is supplied
to
the heating element. Heatfrom the
element causes the bi-metal strip to coil. The coiling
action of the bi-metal strip turns the choke
shaft
and
gradually opens the choke plate. Heat from the element
keeps the choke open while the engine is running.
The choke gets very hot during nor-
-1
mal operation and can cause severe
burns if touched.
Do
not
touch the choke assembly
during
and
after set operation.
Allow
the set to cool
down
before working on the choke assembly.
If
the engine starts but runs roughly and blowsout black
smoke after a minute or two of operation, the choke is
set
too
rich.
If
the engine starts but sputters or stops
before it warms up, the choke is set
too
lean.
Choke Adjustment:
An adjustment screw
is
mounted on
the bottom
of
the choke assembly (see Figure
6-14)
for
making choke setting adjustments. Turn the adjustment
screw clockwise to lean the system and counterclock-
wise
to
increase richness.
If
the choke has been replaced
or
is way out of adjust-
ment, use the following procedures toestablish an initial
choke setting.
Allow the generator set
to
cool down (an ambient
temperature of approxi'mately
75°F
[24OC]
is
required) before making initial setting.
Move the choke lever back and forth
to
check for
free movement. Verify that choke does not bind
or
stick.
Slowly rotate the adjustment screw on the bottom of
the choke assembly
so
that the choke lever
is
held in
the center of its travel.
Move the choke lever back and forth to check for
smooth operation. Choke lever should return auto-
matically
to
the center position when released from
the open position without sticking
or
binding.
FS-1762
FIGURE
6-14. CHOKE ASSEMBLY
Choke Replacement:
If
the choke fails to open,
check
to
see
if
the heating element
is
working. The
heating element cover should become
hot
after a
few minutes of operation.
If
the element cover does
not get hot, start the set and then use an AC voltme-
ter to check for voltage (approximately
20
VAC) at
the element cover terminals.
If
voltage is not pres-
ent, check for opens or shorts in the control wiring.
If
the voltage is presentat the heating element cover
terminals, stop the set and remove the heating ele-
ment cover. Inspect the heating element and
replace
if
burned out or broken. Also inspect the
bi-metal spiral strip and replace if damaged, deteri-
orated,
or
dragging in the housing.
When installing a new bi-metal strip, maintain the
original direction
of
spiral (see Figure
6-15).
The
outer tab must point in a clockwise direction. Make
sure the coil rests squarely in the housing and the
inner end of the coil engages the
slot
in the choke
shaft. When installing the element cover, makesure
the slotted tang on the cover engages the bi-metal
strip.
CLOCKWISE
\
4
\.
,
OUTER
TAB
FS-1606-1
FIGURE
6-15. BI-METAL SPIRAL
STRIP
6-1
6
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