2021 FORD F-350 warning

Your vehicle has a fuel and water separator
that recirculates fuel from the engine to
help prevent fuel filter clogging. To avoid
engine fuel starvation during cold weather
operation of 32°F (0°C) or below, we
recommend that the fuel level in your tank
should not drop below ¼ full. This helps
prevent air from entering the fuel system
and stalling the engine.
Your vehicle has a selective catalytic
reduction system that uses Diesel Exhaust
Fluid (DEF) to operate properly. You need
to replenish your vehicle ’s DEF at certain
intervals. When filling your vehicle ’s DEF
tank in cold weather, take special care to
prevent damage to the tank. See
Selective Catalytic Reductant System
(page
197).
In cold weather below
32°F (0°C), the
engine may slowly increase to a higher idle
speed if you leave it idling in park (P). As
the engine warms-up, the engine sound
level decreases due to the activation of
PCM-controlled sound reduction features.
If you operate your vehicle in a heavy
snowstorm or blowing snow conditions,
snow and ice can clog the engine air
induction. If this occurs, the engine may
experience a significant reduction in power
output. At the earliest opportunity, clear
all the snow and ice away from inside the
air filter assembly. Remove the air cleaner
cover and the air filter and remove any
snow or ice. Remove any debris, snow or
ice, on the foam filter by brushing the
surface with a soft brush. Once you have
cleared all of the debris, reinstall the air
filter and cover.
Do not use water, solvents, or a hard brush
for cleaning the foam filter. WARNING:
To reduce the risk of
vehicle damage and personal burn
injuries, do not start your engine with the
air cleaner removed and do not remove
it while the engine is running.
In order to operate the engine in
temperatures of 32°F (0°C) or lower, read
the following instructions:
• Make sure that the batteries are of
sufficient size and are fully charged.
Check other electrical components to
make sure they are in optimum
condition.
• Use the proper coolant solution at the
concentration recommended
protecting the engine against damage
from freezing.
• Try to keep the fuel tank full as much
as possible at the end of operation to
prevent condensation in the fuel
system.
• Make sure you use proper cold weather
engine oil and that it is at its proper
level. Also, if necessary, make sure to
follow the engine oil and filter change
schedule found under the Special
operating conditions section listed in
the scheduled maintenance
information.
• At temperatures of
-9°F (-23°C) or
below, it is recommended that you use
an engine block heater to improve cold
engine starting.
• If operating in arctic temperatures of
-20°F (-29°C)
or lower, consult your
truck dealer for information about
special cold weather equipment and
precautions.
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Super Duty (TFE) Canada/United States of America, enUSA, Edition date: 202008, Third-Printing- Starting and Stopping the Engine

We recommend the following cold
weather idling guidelines:
•
You can use Motorcraft® cetane
improvers or non-alcohol-based
cetane improvers from a reputable
manufacturer as needed.
• Maintain the engine cooling system
properly.
• Avoid shutting the engine down after
an extensive idling period. Drive your
vehicle for several miles with the
engine at normal operating
temperatures under a moderate load.
• Consider using an engine block heater.
• For extended idle times use an
approved idle speed increase device.
Winter Operating Tips for Arctic
Operation -20°F (-29°C) and Below
The following information is a guideline
only and is not to be the only source of
possible solutions in resolving extreme
cold temperature issues.
Starting Aids WARNING: Do not use starting
fluid, for example ether, in the air intake
system. Such fluid could cause
immediate explosive damage to the
engine and possible personal injury.
The use of the factory engine block heater
assists in engine starting in extreme cold
ambient temperatures
See Engine Block
Heater (page 182). Idle Control
Your vehicle may have a factory option for
a stationary elevated idle control through
the upfitter switches in the overhead
console. This allows the operator to
elevate the idle RPM for extended idle
periods, as well as aftermarket equipment
such as PTO operation. You must configure
this feature even if ordered from the
factory. See your authorized dealer for
required upfitting.
Operation in Snow and Rain
Vehicle operation in heavy snowfall or
extreme rain conditions may feed
excessive amounts of snow or water into
the air intake system. This could plug the
air filter with snow and may cause the
engine to lose power and possibly shut
down.
We recommend the following actions after
operating your vehicle up to
200 mi
(320 km) in snowfall or extreme rain:
• Snow: At the earliest opportunity, open
the hood and clear all the snow and ice
from the air filter housing inlet (do not
remove the foam filter) and reset the
air filter restriction gauge.
Note: Removal of the foam filter degrades
your vehicle performance during snow and
hot weather conditions.
• Extreme rain: The air filter dries after
about 15– 30 minutes at highway
speeds. At the earliest opportunity,
open the hood and reset the air filter
restriction gauge.
Refer to Air filter and restriction gauge in
the Maintenance chapter for more
information. See
Changing the Engine
Air Filter (page 358).
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Super Duty (TFE) Canada/United States of America, enUSA, Edition date: 202008, Third-Printing- Starting and Stopping the Engine

Operation in Standing Water
Ingestion of water into the diesel engine
can result in immediate and severe
damage to the engine. If driving through
water, slow down to avoid splashing water
into the intake. If the engine stalls, and you
suspect ingestion of water into the engine,
do not try to restart the engine. Consult
your dealer for service immediately.
Your fuel tank vents to the atmosphere by
valves on top of the tank and through the
fuel cap. If water reaches the top of the
tank, the valves may pull water into the
fuel tank. Water in the fuel can cause
performance issues and damage the fuel
injection system.
SWITCHING OFF THE ENGINE
- 6.7L DIESEL
Switch the ignition off.
To help prolong engine life, we
recommended you allow the engine to idle
for three to five minutes, especially after
any of the following:
•
Continuous engine speed.
• High ambient temperature.
• High GVW or GCW operation, for
example heavy loads or trailers.
This allows the turbo charged engine to
cool down.
ENGINE IDLE SHUTDOWN (IF
EQUIPPED)
Your vehicle may be equipped with an
engine idle shutdown system. This system
automatically shuts down your engine
when it has been idling in
P (Park) or N
(Neutral) for five minutes (parking brake
set) or 15 minutes (parking brake not set).
When the engine idle shutdown process
has started: •
A chime sounds and the information
display will show ENGINE TURNS OFF
IN 30 (seconds) and start counting
down
• You can restart the five or 15-minute
timer by changing the position of the
accelerator pedal, brake pedal or the
park brake within the final 30 seconds
• When the timer reaches zero, the
engine shuts down and this message
will appear in your information display
ENGINE TURNED OFF
• One minute after the engine has shut
down, the electrical system simulates
key off, even though the ignition is still
in the on position, initiating normal
accessory delay period
• You must move the ignition to the off
position to reset the system before
restarting your vehicle.
The engine idle shutdown idle timer does
not start if:
• The engine is operating in power
take-off mode.
• The engine coolant temperature is
below 60°F (16°C).
• The exhaust emission control device is
regenerating.
ENGINE BLOCK HEATER
(IF
EQUIPPED) WARNING:
Failure to follow engine
block heater instructions could result in
property damage or serious personal
injury. WARNING: Do not use your heater
with ungrounded electrical systems or
two-pronged adapters. There is a risk of
electrical shock.
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Super Duty (TFE) Canada/United States of America, enUSA, Edition date: 202008, Third-Printing- Starting and Stopping the Engine

SAFETY PRECAUTIONS
WARNING: Do not overfill the fuel
tank. The pressure in an overfilled tank
may cause leakage and lead to fuel spray
and fire. WARNING:
The fuel system may
be under pressure. If you hear a hissing
sound near the fuel filler inlet, do not
refuel until the sound stops. Otherwise,
fuel may spray out, which could cause
serious personal injury. WARNING:
Automotive fuels can
cause serious injury or death if misused
or mishandled. WARNING:
Flow of fuel through a
fuel pump nozzle can produce static
electricity. This can cause a fire if you are
filling an ungrounded fuel container. WARNING:
Fuel may contain
benzene, which is a cancer-causing
agent. WARNING: When refueling always
shut the engine off and never allow
sparks or open flames near the fuel tank
filler valve. Never smoke or use a cell
phone while refueling. Fuel vapor is
extremely hazardous under certain
conditions. Avoid inhaling excess fumes.
Observe the following guidelines when
handling automotive fuel:
• Extinguish all smoking materials and
any open flames before refueling your
vehicle.
• Always turn off the vehicle before
refueling. •
Automotive fuels can be harmful or
fatal if swallowed. Fuel such as
gasoline is highly toxic and if
swallowed can cause death or
permanent injury. If fuel is swallowed,
call a physician immediately, even if no
symptoms are immediately apparent.
The toxic effects of fuel may not be
visible for hours.
• Avoid inhaling fuel vapors. Inhaling too
much fuel vapor of any kind can lead
to eye and respiratory tract irritation.
In severe cases, excessive or prolonged
breathing of fuel vapor can cause
serious illness and permanent injury.
• Avoid getting fuel liquid in your eyes. If
fuel is splashed in the eyes, remove
contact lenses (if worn), flush with
water for 15 minutes and seek medical
attention. Failure to seek proper
medical attention could lead to
permanent injury.
• Fuels can also be harmful if absorbed
through the skin. If fuel is splashed on
the skin, clothing or both, promptly
remove contaminated clothing and
wash skin thoroughly with soap and
water. Repeated or prolonged skin
contact with fuel liquid or vapor causes
skin irritation.
• Be particularly careful if you are taking
Antabuse or other forms of Disulfiram
for the treatment of alcoholism.
Breathing gasoline vapors could cause
an adverse reaction, serious personal
injury or sickness. If fuel is splashed on
the skin, wash the affected areas
immediately with plenty of soap and
water. Consult a physician immediately
if you experience any adverse reactions.
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Super Duty (TFE) Canada/United States of America, enUSA, Edition date: 202008, Third-Printing- Fuel and Refueling

exported to non- ultra low sulfur diesel fuel
markets will need to be retrofitted at the
customer
’s expense using Ford authorized
dealer service parts in order to be reliably
operated on non- ultra low sulfur diesel
fuel.
Biodiesel WARNING: Do not mix diesel with
gasoline, gasohol or alcohol. This could
cause an explosion.
Note: Do not use home heating oil,
agricultural fuel, raw fats and oils, waste
cooking greases, biodiesel greater than 20%
or any diesel not intended for highway use.
Damage to the fuel injection system, engine
and exhaust catalyst, and diesel particulate
filter can occur if you use an improper fuel.
Red dye is used to identify fuels intended
for agricultural and non-highway use.
You may operate your vehicle on diesel
fuels containing up to 20% biodiesel, also
known as B20.
Biodiesel fuel is a chemically converted
product from renewable fuel sources, such
as vegetable oils, animal fats and waste
cooking greases.
To help achieve acceptable engine
performance and durability when using
biodiesel in your vehicle:
• Confirm the biodiesel content of the
fuel to be B20 (20% biodiesel) or less
• Only use biodiesel fuel of good quality
that complies with industry standards
• Follow the recommended service
maintenance intervals
See General
Maintenance Information (page 565). •
Do not store biodiesel fuel in the fuel
tank for more than 1 month
• Consider changing brands or reducing
biodiesel content if you have cold
temperature fuel gelling issues or a
frequent LOW FUEL PRESSURE
message appearing
Use of biodiesel in concentrations greater
than 20% may cause damage to your
vehicle, including engine and/or exhaust
after-treatment hardware (exhaust
catalyst and particulate filter) failures.
Concentrations greater than 20% can also
cause fuel filter restrictions that may result
in a lack of power or damage to fuel
system components, including fuel pump
and fuel injector failures.
We recommend SAE 5W-40 oil for fuels
with greater than 5% biodiesel (B5). For
more information about oil change
intervals and other maintenance when
operating on biodiesel
See Special
Operating Conditions Scheduled
Maintenance
(page 574).
Look for a label on the fuel pump to
confirm the amount of biodiesel contained
in a diesel fuel. Biodiesel content is often
indicated with the letter B followed by the
percent of biodiesel in the fuel. For
example, B20 indicates a fuel containing
20% biodiesel. Ask the service station
attendant to confirm the biodiesel content
of a diesel fuel if you do not see a label on
the fuel pump.
Biodiesel fuels degrade more easily than
diesel fuels not containing biodiesel and
should not be stored in the fuel tank for
more than 1 month. If you plan to park or
store your vehicle for more than 1 month,
then you should empty your vehicle fuel
tank of biodiesel fuel. You should fill the
tank with a pure petroleum-based diesel
fuel and run your vehicle for a minimum of
30 minutes.
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Super Duty (TFE) Canada/United States of America, enUSA, Edition date: 202008, Third-Printing- Fuel and Refueling

Note:
Degraded or oxidized biodiesel can
damage fuel system seals and plastics and
corrode steel parts.
During cold weather, if you have problems
operating on biodiesel, you may need to
use a diesel fuel with lower biodiesel
content, try another brand, or discontinue
the use of biodiesel.
Diesel Fuel Additives
It should not be necessary to add any
aftermarket additives to your fuel if you
use a high quality diesel fuel that conforms
to ASTM industry specifications.
Aftermarket additives can damage the fuel
injector system or engine.
Use Motorcraft® cetane booster or an
equivalent cetane booster additive if you
suspect fuel has low cetane. Use
Motorcraft® anti-gel & performance
improver or an equivalent additive if there
is fuel gelling.
Do not use alcohol-based additives to
improve cetane quality, to prevent fuel
gelling or any other use. The use of alcohol
additives may result in damage to the fuel
injectors and system. See Engine
Specifications (page 441).
Your warranty may not cover repairs
needed to correct the effects of using an
aftermarket product that does not meet
Ford specifications in your fuel.
RUNNING OUT OF FUEL WARNING:
Flow of fuel through a
fuel pump nozzle can produce static
electricity. This can cause a fire if you are
filling an ungrounded fuel container.
Avoid running out of fuel because this
situation may have an adverse effect on
engine components. If you have run out of fuel:
•
You may need to cycle the ignition from
off to on several times after refueling
to allow the fuel system to pump the
fuel from the tank to the engine. On
restarting, cranking time will take a few
seconds longer than normal. With
keyless ignition, just start the engine.
Crank time will be longer than usual.
• Normally, adding
1 gal (4 L) of fuel
preferably gasoline, is enough to restart
the engine. If the vehicle is out of fuel
and on a steep grade, more than
1 gal
(4 L) may be required.
REFUELING - GASOLINE WARNING: When refueling always
shut the engine off and never allow
sparks or open flames near the fuel tank
filler valve. Never smoke or use a cell
phone while refueling. Fuel vapor is
extremely hazardous under certain
conditions. Avoid inhaling excess fumes. WARNING:
Fuel vapor burns
violently and a fuel fire can cause severe
injuries. WARNING: Read and follow all the
instructions on the pump island. WARNING:
Stay outside your
vehicle and do not leave the fuel pump
unattended when refueling your vehicle. WARNING:
Keep children away
from the fuel pump. Never let children
pump fuel. WARNING:
Wait at least five
seconds before removing the fuel pump
nozzle to allow any residual fuel to drain
into the fuel tank.
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Super Duty (TFE) Canada/United States of America, enUSA, Edition date: 202008, Third-Printing- Fuel and Refueling

WARNING: Stop refueling after the
fuel pump nozzle automatically shuts
off for the second time. Failure to follow
this will fill the expansion space in the
fuel tank and could lead to fuel
overflowing. WARNING: Do not remove the fuel
pump nozzle from its fully inserted
position when refueling.
Use the following guidelines to avoid
electrostatic charge build-up when filling
an ungrounded fuel container:
• Place approved fuel container on the
ground.
• Do not fill a fuel container while it is in
the vehicle - including the cargo area.
• Keep the fuel pump nozzle in contact
with the fuel container while filling.
• Do not use a device that would hold
the fuel pump handle in the fill position.
Fuel Filler Cap WARNING: The fuel system may
be under pressure. If you hear a hissing
sound near the fuel filler inlet, do not
refuel until the sound stops. Otherwise,
fuel may spray out, which could cause
serious personal injury.
Note: If you must replace the fuel filler cap,
replace it with a fuel filler cap designed for
your vehicle. The vehicle warranty may be
void for any damage to the fuel tank or fuel
system if you do not use the correct genuine
Ford or Motorcraft® fuel filler cap.
When fueling your vehicle:
1. Put your vehicle in park (P).
2. Switch the engine off. 3. Carefully turn the filler cap
counterclockwise until it spins off.
4. Pull to remove the cap from the fuel filler pipe.
5. To install the cap, align the tabs on the
cap with the notches on the filler pipe.
6. Turn the filler cap clockwise until it clicks at least once.
If the Check Fuel Cap light or a Check Fuel
Cap message appears in the instrument
cluster and stays on after you start the
engine, you may not have installed the fuel
filler properly.
If the fuel cap light remains on, at the next
opportunity, safely pull off of the road,
remove the fuel filler cap, align the cap
properly and reinstall it. The check fuel cap
light or Check fuel cap message may not
reset immediately. It may take several
driving cycles for the indicators to turn off.
A driving cycle consists of an engine
start-up, after four or more hours with the
engine off, followed by normal city and
highway driving.
REFUELING - DIESEL WARNING: Read and follow all the
instructions on the pump island. WARNING:
Stay outside your
vehicle and do not leave the fuel pump
unattended when refueling your vehicle. WARNING:
Keep children away
from the fuel pump. Never let children
pump fuel. WARNING:
Wait at least five
seconds before removing the fuel pump
nozzle to allow any residual fuel to drain
into the fuel tank.
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Super Duty (TFE) Canada/United States of America, enUSA, Edition date: 202008, Third-Printing- Fuel and Refueling

WARNING: Do not remove the fuel
pump nozzle from its fully inserted
position when refueling. WARNING: When refueling always
shut the engine off and never allow
sparks or open flames near the fuel tank
filler valve. Never smoke or use a cell
phone while refueling. Fuel vapor is
extremely hazardous under certain
conditions. Avoid inhaling excess fumes. WARNING: Stop refueling after the
fuel pump nozzle automatically shuts
off for the second time. Failure to follow
this will fill the expansion space in the
fuel tank and could lead to fuel
overflowing. WARNING: The fuel system may
be under pressure. If you hear a hissing
sound near the fuel filler inlet, do not
refuel until the sound stops. Otherwise,
fuel may spray out, which could cause
serious personal injury.
Note: If you must replace the fuel filler cap,
replace it with a fuel filler cap designed for
your vehicle. The vehicle warranty may be
void for any damage to the fuel tank or fuel
system if you do not use the correct genuine
Ford or Motorcraft® fuel filler cap.
Fueling Tips
If air is allowed to enter the fuel system the
engine automatically purges any trapped
air. To purge the air sooner: prior to engine
start, prime the system by turning the key
to on for 30 seconds then to off. Repeat
this several times. The engine may run
rough and produce white smoke while air
is in the system. This is normal.
Use only clean, approved containers that
prevent the entry of dirt or water whenever
you store diesel fuel. Diesel fuel must not be stored in a
galvanized container. The fuel can dissolve
the zinc in the galvanized container. The
zinc then remains in the fuel. If you run the
contaminated fuel through the engine, the
zinc can deposit in the fuel injectors
causing expensive-to-repair damage.
Diesel fuel dispensing nozzle fill rate
Your vehicle has a fuel fill pipe that is able
to accept fuel up to
20 gal (76 L) per
minute from a 1.2 in (30 mm)
fuel-dispensing nozzle. Pumping fuel at
greater flow rates may result in premature
nozzle shut-off or spit back.
Truck stops have pumps and nozzles
designed for larger, heavy-duty trucks.
When refueling at truck stops: if the nozzle
shuts off repeatedly when refueling, wait
5– 10 seconds; then use a slower rate of
flow, do not depress the nozzle trigger as
far.
Refueling
When fueling your vehicle do the following:
1. Fully open the fuel tank filler door and remove the fuel tank filler cap.
Carefully turn the filler cap
counterclockwise until it spins off.
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Super Duty (TFE) Canada/United States of America, enUSA, Edition date: 202008, Third-Printing- Fuel and Refueling