Chevrolet CAMARO 1979 Service Manual page 598

CC.46 FU EL SYSTEM
C H O K E S Y S T E M
F A S T I D L E F À À 1 L Ô L E T A N G
Figure 6C I Choke System
dùring âll ranges ofengine operation. Becauseofthis system
control, new Mixture Conrrol Adjustment procedures are
required. For exâmple: the previously used propane
enrichment or lean drop methods ofidle mixture adjustment
mây not be used when âdjusting carburetors with th€ EFC
Syslem because syslem control will chang€ airlfuei mixtures
to lean or rich âs ùe mixture screws are adjusted rich or
NOTICET THE ELECTRONIC FUEL CONTROL
SYSTEM IS SENSITIVE TO ANY CHANCE IN
MTXTURE CONTROL ADJUSTMENT WHICH,
IF IMPROPERLY SET, CAN IMPAIR THE
ABILITY
OF THE SYSTEM TO MAINTAIN
PRECISE CONTROL OF CARBURETOR ATR/
FUEL MIXTURES. PLUGS ARE INSTALLED IN
THE CARBURETOR AIR HORN AND OVER
THE IDLE MIXTURE
NEEDLES IN THE
THROTTLE BODY TO SEAL THE FACTORY
SETTINGS. FOR THIS REASON. THE MIXTURE
CONTROL ADJUSTMENT POINTS, LISTED
BELOW, SHOULD NEVER BE CHANGED FROM
THE ORIGINAL FACTORY SETTING.
HOWEVER, IF IN DIACNOSIS
THE
"PRELIMINARY SYSTEM PERFORMANCE
CHECK" INDICATES THE CARBURETOR TO
BE THE CAUSE OF A DRIVER PERFORMANCE
COMPLÀINT OR EMISSIONS FAILURE, OR
CRITICAL PARTS SUCH AS ÀIR HORN, FLOÀT
BOWL. THROTTLE BODY, NEEDLË AND SEAT,
OR FLOATARE REPLACED, THENTHE PLUGS
MAY BE REMOVED AND THE MIXTURE
CCNTROL ADJUSTMËNTS
MADE,
or grinding sumcient material offthe gage to âllow inseltion
down the vertical vent "D" shâped hole in the air horn
casting (next to the ldle Air Bleed Vâlv€ Plug) (Figùre 6C-
15). Check rhat gage fr€ely enters "D' vent hole and does
not bind. Th€ gâge will be used to determine lotal mixture
conlrol solenoid travel.
with engine off, air cleâner ând gasket removed,
measure mixture control solenoid travel as follows;
a. Insert modified Float Oâge J-9789-ll0 down "D"
shaped vent hole. Press down on gage and release, observing
that gage moves freelyânddoes notbind. With gâgereleased
(Solenoid up position), r€ading at eye level record mark on
gage (in inch€s) that lines up wilh top of air horn casting.
b. Then, lightly press down on gage until bottomed
(Solenoid down position). Record in inches mark on gâge
that lines up with top of air horn casting.
c. Subtrâct gâge up dimension (ilem
'â') from gage
down dimension (ilem 'b') and record differ€nce (in
inchet. The difference in dimensions is totâl solenoid
trâve1.
d. Iftotal solenoid travel (item "c") is greâter or less
thân 3/32 +
1/32", make mixture control Solenoid
adjustments as noted below.
M I X T U R E C O N T R O L S O L E N O I D
A D J U S T M E N T S
Ifextemal gaee check (item "d' above) shows the totâl
Solenoid travel is incorrect, proceed as follows:
1. Remov€ air horn following normâl service
2. Using a suitable tool on upper eûd ofmixture control
Solenoid screw (in float bowl), turn screw clockwise until
bottomed lightly in bowl, counting numb€r ol turns until
scrow is bottomod. If number of turns counted is greâter
thar' 2-l/2 twtns, or less than 1'll2 turns, solenoid travei
was incorrecl, In this case, reset mixture control solenoid
screw (see step 3). Ifsolenoid screw setting is correct (1-il2
to 2-1,/2 turns), ir will be neaessary to reset solenoid stop
screw in air hom (see step 4).
NOTICE: Do not bottom Solenoid scrgw by
lorcing - to do so mây r€sult in br8âkâgo of
th6screwhoad. Do not use pliers,which could
damâge or break scr€w.
3. From bottomed position, turn Solenoid screw
counterclockwise until the scr€w is backed out of th€ bowl
EXACTIiY 2 turns.
4. Invert air horn ând using a suitable wrench, remove
Solenoid stop screw, and spring (if used), from air horn.
With stop screw removed, drive out smâll plug located
between 'D" shâp€d vent holes lo gain âccess to the
Solenoid stop screw (when instâlled). Reinstall Solenoid
stop screw, and spring (if used), in air horn untii screw is
bottomed lightly.
5. R€install air horn and new gasket on float bowl.
6. Insert exiemal gage in vent hole and with a suitable
tool irsened in smâil hole in air horn, turn mixture control
Solenoid stop screw clockwise until totâl Solenoid travel is
within specified lirnits. (See Solenoid Travel Checkitg
Proc€dure. item "d". above).
CAREFULLY
FOLLOWING FACTORY
RECOMMENDED PROCÊDURES OUTLINED
BELOW.
E X T E R N A L G A G E C H E C K
Before proceeding, a check ofmixture coûtrol solenoid
adjustments can be made on the vehicle. It will be n€cessary
to modify Floa! Gag€ J-9789-130 (used to €xternally check
float level setting on Duâljet and Quâdrajet models) byfiling