JLG 110HX Service Manual - Manual (Page 57)

SECTION 2 - PROCEDURES
3120864 – JLG Lift – 2-33
2.16 THROTTLE CHECKS AND PRECISION
GOVERNOR ADJUSTMENTS - FORD
ENGINE
Checks
1. Check that anti-dieseling solenoid is operating. If
solenoid is operating, an audible click at the carbu-
retor should be heard when the ignition is switched
on.
2. Check throttle linkage for smooth operation by rotat-
ing throttle lever by hand to full throttle position, then
slowly back to idle position, felling closely for stick-
ing or binding. To accomplish this, the throttle must
first be disconnected.
Choke Adjustments
NOTE: Automatic choke and vacuum pulloff adjustment pro-
cedure to be made only on a cold engine.
1. Make sure choke body and mounting bracket are
positioned so that choke rod moves freely with no
binding anywhere through its stroke.
2. The choke spring should hold the choke plate firmly
closed but require only slight finger pressure to
open at 70 degrees F (21 degrees C).
3. Retract pulloff shaft until it bottoms (as if under
engine vacuum). Bend pulloff rod until a 9.5 mm rod
just fits between choke plate and carburetor body.
4. The above procedure outlines the correct choke
system environment for most conditions. Some envi-
ronments such as high altitude, very warm or very
cold temperatures may require that the choke cover
be set richer or leaner, or the amount of pulloff may
need to be varied somewhat.
Carburetor and Governor Adjustments
1. With the aid of an assistant, start the engine at the
platform console and allow it to come up to operat-
ing temperature with the air cleaner installed. Adjust
carburetor idle screw until engine idles at 1000 RPM.
Shut down engine.
NOTE: Steps 2, 3, and 4 are preliminary settings.
2. With engine shut down, turn ‘low (mid) engine’
adjusting screw CCW to the stop. Do not turn past
stop, as this breaks the pot, disabling the governor.
3. On controller, turn ‘high engine’ (P1) adjusting screw
25-30 turns CCW, then 10 turns CW.
4. On controller, turn ‘gain’ (P2) adjusting screw CCW
to the stop, then CW until screw slot is vertical
(approximately 1/4 turn).
5. On controller, turn ‘droop’ (P3) adjusting screw CCW
to the stop, then CW until screw slot is vertical
(approximately 1/4 turn). No further adjustment
should be necessary to ‘droop’ (P3).
6. With the aid of an assistant at platform control con-
sole, start engine and allow to come up to operating
temperature. Then have assistant depress foot-
switch and place engine speed switch to HIGH
ENGINE.
7. If engine surging occurs at this point, turn ‘gain’ (P2)
adjusting screw CCW until surging ceases. Turn
‘high engine’ (P1) adjusting screw until engine runs
at 3000 RPM. Turning the screw CW increases RPM.
Turning the screw CCW decreases RPM.
8. While your assistant continues to depress the foot-
switch, have them place engine speed switch to
LOW ENGINE. Turn ‘low (mid) engine’ adjusting
screw until engine runs at 1625 RPM. Turning the
screw CW increases RPM. Turning the screw CCW
decreases RPM. Shut down engine.
NOTE: If engine surges under no load and you cannot get
enough response from adjusting ‘gain’ (P2), try
adjusting surge screw on actuator. Loosen surge
screw locknut. Disconnect throttle linkage. Turn
surge screw CW until linkage arm moves. Manually
stroke the linkage fully and allow to return slowly
until it stops. Try to move linkage toward return posi-
tion. If linkage moves, turn surge screw CCW 1/2
turn. Again stroke linkage and allow to return slowly
until it stops. Try to move linkage toward return posi-
tion. If linkage moves, turn surge screw CCW 1/2
turn. Again stroke linkage and allow to return slowly
until it stops. Try to move linkage toward return posi-
tion. If linkage moves, turn surge screw CCW 1/2
turn. Repeat this procedure until linkage does not
move after stroking. This will set buffer spring ten-
sion properly. Reconnect throttle linkage.
9. With engine speed switch set to LOW ENGINE,
when footswitch is depressed, engine should imme-
diately respond. If response times lags, turn ‘gain’
(P2) adjusting screw CW to improve response time.
Turn adjusting screw in small increments only until
response time is correct. Turning adjusting screw
too far CW can cause surging. (See step (7) above.)