2008 FORD F750 fuel

a buildup of heavy deposits of carbon and rust on valve stems causing
them to stick which, in turn, can cause valvetrain damage.
Winter fronts
The use of winter fronts, or other air-restrictive devices mounted in front
of the radiator on vehicles with chassis-mounted charge air coolers, are
not recommended unless extremely cold weather conditions exist. Air
flow restriction can cause high exhaust temperatures, power loss,
excessive fan usage and a reduction in fuel economy. If you must use a
winter front, the device should have a permanent opening of at least 120
sq in. (774 sq. cm) directly in line with the fan hub.
Hot weather operation
•Keep the engine cooling system filled with a clean, permanent coolant
solution to protect against damage from overheating.
•Fill the fuel tank at the end of daily operation to prevent condensation
in the fuel system.
•Keep external surfaces of the engine, radiator, charge air cooler, A/C
condenser and accessories clean to avoid dirt build-up.
Above normal coolant temperatures could be experienced while driving
in a transmission gear ratio which lugs the engine. To correct this
problem, engine speed should be increased by downshifting in to the
next lower gear to increase engine RPM.
Starting a turbocharged engine with the vehicle on a steep grade
When starting a diesel engine when the loaded vehicle is on a grade, the
engine RPM will start to fall slightly when the clutch is engaged; do not
disengage the clutch and try to increase engine RPM as this may damage
driveline components. The engine will recover as the vehicle begins
moving.
Engine shutdown
Allow the engine to idle for three to five minutes before shutting it
down. The larger the engine, the greater the need for this idling period.
However, do not let the engine idle for more than 10 minutes.
Restarting after running out of fuel
The fuel system may need to be purged of air, refer toRunning out of
fuelin theMaintenance and Specificationschapter.
2008 F-650/750(f67)
Supplement
USA(fus)
Driving
88

GENERAL OPERATING INSTRUCTIONS
•Avoid extended and unnecessary idling.
•Start the vehicle in motion by using the highest gear speed in the
transmission that will let the engine easily start the load without
slipping the clutch.
•Accelerate smoothly and evenly; rapid acceleration increases fuel
consumption without increasing engine performance.
•When approaching a hill, depress the accelerator smoothly to start the
incline at full power, then shift down as needed to maintain vehicle
speed.
•When going down a hill, or long steep grades, prevent over-speeding
of the engine. The engine governor has no control over engine speed
when it is being pushed by a loaded vehicle.
•Always shift to a lower gear at high altitudes to prevent engine
smoking.
•Operate in a gear that will permit an engine speed not in excess of the
maximum governed speed or high-idle RPM (no load).
•Normally, choose the same gear to descend the hill that you would use
to ascend the hill.
All vehicles have blind spots. To reduce the risk of severe injury
or property damage, never move your vehicle to the side or rear
or change lanes without being sure your way is clear on both sides and
to your rear.
Backing up
To reduce the risk of the possibility of personal injury while
backing the vehicle, always be sure your vehicle’s path is clear.
Before backing your vehicle, be sure you can do so safely. If anything
behind the cab limits your view, do not rely on mirrors alone to ensure
that your intended path is clear. If other people are in the vicinity, have
someone standing well behind your vehicle and outside of your intended
path (visible through an exterior mirror) guide you as you back up.
Although OSHA or some governmental regulations may require the use
of an electrical or mechanical back-up alarm to warn bystanders, such an
alarm does not ensure that the intended path is clear. When in doubt,
2008 F-650/750(f67)
Supplement
USA(fus)
Driving
89

The parking BRAKE warning lamp
in the instrument cluster illuminates
and will remain illuminated (when
the ignition is turned on) until the
parking brake is released.
Push the palm release lever on the
parking brake handle and push
down as far as possible to release
the brake. Driving with the parking
brake on will cause the brakes to
wear out quickly and reduce fuel
economy.
If the parking brake is fully
released but the parking
brake warning lamp remains
illuminated, the brakes may not be
working properly. See your dealer
or a qualified service technician.
The parking brake is not
recommended to stop a moving
vehicle. However, if the normal
brakes fail, the parking brake can be
used to stop your vehicle in an
emergency. Since the parking brake only applies retardation to the rear
wheels, the vehicle’s stopping distance will increase greatly and the
handling of your vehicle will be adversely affected.
POWER PARK (AIR-OPERATED PARKING BRAKE) OPTION
(IF EQUIPPED)
This feature uses a brake chamber mounted on the chassis to power a
spring-applied, air-released driveline parking brake. It is controlled by a
yellow, dash-mounted parking brake knob.
P
BRAKE
2008 F-650/750(f67)
Supplement
USA(fus)
Driving
94

Some Dana/Spicer drive axles have a driver-controlled differential lock.
The differential lock can lock or unlock the differential when the vehicle
is moving or stopped. When extra traction is required, the differential
lock will provide full power to both axles.
When the differential is locked, the vehicle’s turning radius will increase
(vehicle will “under-steer”)
The differential can be locked or unlocked when the vehicle is moving at
a constant speed of less than 25 mph (40 km/h) and while the wheels
are not slipping. The differential must not be locked when the vehicle is
traveling down steep grades and traction is minimal.
Note:Never use the differential lock at vehicle speeds above 25 mph
(40 km/h).
Note:The driver-controlled differential lock function will vary with some
transmissions.
•Vehicles equipped with an Allison 3000 Series transmission:The
differential lock and differential lock light will automatically disengage
at speeds above 25 mph (40 km/h). The differential lock will remain
off until either the vehicle is restarted or the differential lock switch is
turned off then back on.
•Vehicles equipped with a 5–speed, 6–speed or 7–speed manual:
The differential lock and differential lock light will automatically
disengage at speeds above 25 mph (40 km/h). The differential lock
will remain off until either the vehicle is restarted or the differential
lock switch is turned off then back on.
Axle conversions
It is not recommended, or approved, for axle conversions to be
performed. However, it is understood that, on occasion, aftermarket
add-on axles are installed by others on the truck chassis which allow
operator control for weight transfer from other axles (i.e., air lift axles).
When operating a loaded vehicle, the driver must keep all
adjustable axles on the ground at all times, supporting their
share of the vehicle’s load. Failure to do so can overload other axles,
tires, wheels, springs, steering components, brakes and frames,
resulting in early component failure, loss of vehicle control, possible
property damage and personal injury.
TWO-SPEED REAR AXLE (IF EQUIPPED)
A two-speed rear axle allows the driver to select a LO range for greater
pulling power and a HI range for greater road speed and fuel economy.
2008 F-650/750(f67)
Supplement
USA(fus)
Driving
125

These ranges can also be used to provide additional steps between
transmission shifts when driving on steep grades and/or fuel economy
may be factors.
Note:Do not shift between ranges when the speed control is on.
Never shift a two-speed axle when descending a steep grade as
this may cause loss of vehicle control and result in personal injury.
Axle shifting
Manual transmissions:
•To downshift,select the next lower gear, release and depress the
accelerator pedal rapidly, or while holding the accelerator pedal down,
release and engage the clutch rapidly.Note:The clutch method is
recommended when driving at slower speeds.
•To upshift,keep the accelerator pedal down, select the next higher
gear, release the accelerator and pause until the axle upshifts.Note:
De-clutch for smoother axle upshifts when driving at slower speeds.
Automatic transmissions:
•Use LO range for when you drive
a fully loaded vehicle on a severe
grade or in congested traffic. To
activate LO range, press the
upper portion of the switch.
•Use HI range for all normal
driving conditions with a lightly
loaded or partially loaded vehicle.
To activate HI range, press the
lower portion of the switch.
Note:You cannot split-shift with an automatic transmission. Also,
downshifting above 40 mph (64 km/h) may result in transmission or axle
damage.
Shifting the axle from LO to HI range - vehicle stopped
Place the transmission in N (Neutral), then press the lower part of the
switch.
Shifting the axle from LO to HI range - vehicle moving
Accelerate to approximately 35 mph (56 km/h), press the lower part of
the switch while the transmission is in N (Neutral), then release and
apply the accelerator.
LOW
2SPD
2008 F-650/750(f67)
Supplement
USA(fus)
Driving
126

Fuse/Relay
LocationFuse Amp
RatingFuse Description
15 10A Interior lamp relay, GEM, Vanity mirrors
16 15A High beams, Indicator
17 — Not used
18 5A Headlamp switch interior lighting
19 15A Engine control
20 5A Starting system
21 10A DRL resistor
22 15A Air horn, Air suspension dump, Two-speed
axle, Driver-controlled locking differential
23 10A Flasher
24 15A ABS, Air dryer, Vacuum pump, Fuel heater
relay
25 10A Function selector switch
26 10A RH low beam headlamp
27 — Not used
28 10A LH low beam headlamp
29 10A Cluster warning lamps, Gauges, GEM,
Hydraulic ABS
30 15A Allison electronic transmission
31 — Not used
Relay 1 — Interior lamps
Relay 2 — Not used
Relay 3 — Horn
Relay 4 — One-touch down window
Relay 5 — Not used
Power distribution box
Always disconnect the battery before servicing high current
fuses.
2008 F-650/750(f67)
Supplement
USA(fus)
Roadside Emergencies
137

To reduce risk of electrical shock, always replace the cover to
the Power Distribution Box before reconnecting the battery or
refilling fluid reservoirs.
Fuse/Relay
LocationFuse Amp
RatingFuse Description
1 15A* Main light switch
2 30A* Power seat (driver)
3 30A* Power seat (passenger)
4 15A* Washer pump relay, Washer pump motor
5 — Not used
6 15A* Air intake heater (Caterpillar engine only)
7 15A* Stoplamp switches (Air brake vehicles only)
8 25A* Fuel heater relay (Caterpillar
engine-equipped vehicles with dual fuel tanks
only)
9 20A* Inhibit relay, Engine ECM, Cluster,
Transmission TCM
10 15A* Heated drain valve
11 30A* Electric trailer brake
2008 F-650/750(f67)
Supplement
USA(fus)
Roadside Emergencies
138

Fuse/Relay
LocationFuse Amp
RatingFuse Description
12 20A* Daytime Running Lamps (DRL), Blend door
actuator, Climate mode, Back-up, Heated
seats, Trailer ABS, Exhaust brake
13 — Not used
14 — Not used
15 7.5A* Body builder - trailer adapter stoplamps
16 5A* Bendix Air ABS (Air brake vehicles only)
WABCO ABS (Hydraulic brake vehicles only)
17 — Not used
18 10A* Fuel transfer pump (duel fuel tanks only)
19 — Not used
20 — Not used
21 10A* Hydromax motor control
22 — Not used
23 — Not used
24 — Not used
101 30A** Bendix Air ABS relay (Air brake vehicles
only)
WABCO ABS modulator relay (Hydraulic
brake vehicles only)
102 20A** Ignition switch to customer access
103 20A** Ignition switch (Junction box fuses 8, 9, 10,
11, 19, 29 and 30)
104 20A** Power point
105 20A** Power door locks
106 30A** Main light switch, Multifunction switch, CJB
fuses 16, 26 and 28, Headlamps, DRL relays
107 50A** Junction box fuses 1, 2, 3, 4, 12, 13, 14 and
15
108 40A** Fuel heater relay (Cummins engine only)
109 40A** Power window relay
110 30A** Wiper power relay (Park, Low/High speed)
2008 F-650/750(f67)
Supplement
USA(fus)
Roadside Emergencies
139