On-Vehicle Service (1Mef); Electric Choke - GMC G Service Manual

6C1-18 CARBURETORS

ON-VEHICLE SERVICE (1MEF)

ELECTRIC CHOKE

I P I Inspect
• Remove the air cleaner. With the engine OFF, hold
the throttle half open. Open and close the choke sev­
eral times. Watch linkage to be certain all links are
connected and there are no signs of damage.
• If the choke or linkage binds, sticks, or works slug­
gishly, clean it with Choke Cleaner X-20-A or equiva­
lent. Use cleaner as directed on the can. Refer to the
disassembly instructions for additional direction if
cleaning does not correct the problem. Do not lubri­
cate the linkage.
• Visually inspect the carburetor to be certain all vac­
uum hoses are connected. Inspect hoses for cracks,
abrasions, hardness or other signs of deterioration.
Replace or correct as necessary.
• The vacuum break diaphragm shaft should be fully
extended when the engine is off. If the shaft is not
fully extended, replace the vacuum break assembly.
Start engine — the vacuum break diaphragm shaft
should fully retract within 10 seconds. If the unit fails
to retract, replace the vacuum break assembly.
• Allow the choke to cool so that when the throttle is
opened slightly, the choke blade fully closes. This
check must be performed at an ambient temperature
of about 21 °C (70°F).
• Start the engine and determine the time required for
the choke blade to reach its full open position. (Begin
timing when the engine starts.) If the choke plate fails
to open fully within five minutes, proceed with the
remaining steps.
• Check voltage at the choke heater connection with
the engine running. If the voltage is approximately 12-
15 volts, replace the electric choke unit. If the voltage
is low or zero, check all wires and connections. If the
connections at the oil pressure switch are dirty or
corroded, the oil warning lamp will be OFF with the
ignition switch ON and the engine OFF. If the fuse is
blown, the radio or turn signal indicator will be inoper­
ative. Repair wires or replace fuses as necessary.
• If all wiring and fuses are good, replace the oil pres­
sure switch.
H Remove or Disconnect (Figure 9)
1. Air cleaner.
2. The choke electrical connector.
3. Rivet heads and retainers.
• Align a #21 drill (0.156-inch) on the rivet head
and drill only enough to remove the rivet head
(figure 9).
Figure 9 — Drilling the Choke Coil Rivets
• Use a drift and a small hammer to drive the
remainder of the rivets from the choke housing.
• Use care during drilling, to prevent damage to
the choke cover or housing.
4. The choke cover assembly from the housing.
5. The choke coil from the housing.
h 4! Install or Connect (Figure 10)
1. The choke cover and coil assembly in the choke
housing.
• Align the notch in the cover with the raised cast­
ing projection on the housing cover flange.
• Make sure the coil pick-up tang engages the
inside choke coil lever.
2. Retainers and rivets using a suitable blind rivet install­
ing tool (figure 10).