Fuel Ratio Control Setting
This is an on engine test to determine if the FRC (Fuel Ratio
Control) is set properly. If the FRC is set properly, no
additional procedures will be needed. If the FRC is set
incorrectly, the governor must be removed and adjusted
Procedures, in 3114, 3116 & 3126 Governor Service Manual,
To determine the FRC settings, complete the following steps:
Install Fuel Setting Indicator Group as instructed in the
"Fuel Setting" section of this manual.
A digital indicator is recommended for the
following test procedures.
If desired, a modified valve cover presented in
June 1993 "Engine News" can be installed. This
will prevent oil loss during completion of this
(1) FRC (Fuel Ratio Control). (2) Boost line port. (3) Low idle
screw. (4) High idle screw.
Disconnect the boost line from the boost line port (2)
and apply air pressure to the boost line port (2).
A regulated air supply of 140 to 270 kPa (20 to 30
psi) MUST be used to avoid damage to the fuel
With the engine operating a low idle quickly actuate the
throttle to high idle position.
Record the maximum reading observed on the digital
indicator as the engine's speed increases to high idle.
This is the dynamic maximum fuel setting value.
Repeat the procedure several times and average the
Static and dynamic engine rack values may vary
due to the method of fuel setting calibration and
differences in governor settings. When adjusting
calibration pin is used as the reference dimension
to the governor. This pin is used on all engines
regardless of governor settings. This common
calibration point along with different settings in
the governor will cause the engine dynamic and
static rack values to differ depending on the
governor part number, since the load stop
settings range between 9.0 mm (.35 in) and 10.4
mm (.41 in). When the pin is in place the governor
travel is restricted, but when the pin is removed
and the engine is running, the governor is
unrestricted. This allows a higher dynamic rack
value than can be obtained statically with the
calibration pin in place.
Disconnect the air pressure from the FRC and vent the
FRC to atmosphere.
With engine operating at low idle, quickly actuate the
throttle to high idle position.
Record maximum reading observed on digital indicator
as the engine's speed increases to high idle. This is the
FRC setting value. Repeat the procedure several times
and average the values.
Subtract the FRC setting value obtained from step
seven from the dynamic maximum fuel setting value
obtained from step four. This difference is the on
engine FRC delta.
Determine the governor's FRC delta by the following
calculation. Subtract the FUEL RATIO CONTROL
specification from the LOAD STOP specification. This
difference is the governor's FRC delta.
Refer to the TMI (Technical Marketing Information)
Governor Bench Performance Data for the correct
If the on engine FRC delta is within ± .20 mm
( .008 in) of the governor FRC delta specifications,
then the FRC is set properly.
If the on engine FRC delta is out of tolerance, the
governor will need to be removed from the engine and
set to specification on the 1U7326 Governor Calibration
For further information on the 1U7326 Governor
Calibration Bench, refer to 3114, 3116 & 3126
Governor Service Manual, SENR6454.