K 30 P/U 4WD V6-262 4.3L (1985)
Fig. 5 Lean & rich mixture screw plug installation. V6-229 & 231 w/E2MC-ME carburetor
MC solenoid travel must be within specifications before idle mixture can be adjusted. Perform check with engine off and air cleaner removed. Before
proceeding, use float gauge J-34935-1 or equivalent, to fit in ``D'' shaped vertical vent on carburetor air horn.
1.
Insert gauge in ``D'' shaped hole. Press down on gauge and release, making sure that gauge moves freely, without binding.
2.
With gauge released (solenoid up position), read gauge at eye level and record reading that lines up with top of air horn casting.
3.
Press down lightly on gauge until bottomed. Record reading where gauge lines up with top of air horn casting.
4.
Subtract reading in step 2 from reading in step 3 to obtain total MC solenoid travel.
5.
If total MC solenoid travel is 2/32-6/32 inch, proceed to ``Idle Air Bleed Valve Adjustment.'' If travel is not within specifications, MC solenoid
must be adjusted.
MC SOLENOID ADJUSTMENT
1.
Remove carburetor air horn and gasket, MC solenoid plunger and plastic filler block.
2.
Remove throttle side metering rod.
3.
Install MC solenoid gauging tool J-33815-1 or equivalent over metering rod jet guide rod, Fig. 3, then re-install MC solenoid plunger.
4.
Hold MC solenoid plunger in down position and turn lean mixture screw counterclockwise until plunger just breaks contact with gauging tool. Use
tool J-28696 or equivalent to adjust lean mixture screw.
5.
Slowly turn lean mixture screw clockwise until plunger just contacts gauging tool. Adjustment is correct when plunger contacts both solenoid stop
and gauging tool, in down position. If adjusted position is less than 3/4 turn different than original position, original adjustment was correct.
6.
Remove solenoid plunger and gauging tool, then reinstall metering rod and plastic filler block.
7.
Remove rich mixture screw from underside of air horn.
8.
Remove lean and rich mixture screw sealing plugs from air horn, Fig. 3, using a suitable punch.
9.
Reinstall rich mixture screw turning until lightly seated, then back screw out 1/4 turn and reinstall air horn using a new gasket.
10.
Adjust MC solenoid travel to 4/32 inch with rich mixture screw, checking as outlined in ``MC Solenoid Check.''
11.
Install new plugs over lean and rich mixture screws as shown, Fig. 4, then proceed to ``Idle Air Bleed Valve Adjustment.'' New plugs must be
installed, as directed, over lean and rich mixture screws in order to retain settings and to prevent fuel vapors from entering the atmosphere.
