1999 FORD MUSTANG Owners Manual

²Keep the fuel pump nozzle in contact with the
fuel container while filling.
²DO NOT use a device that would hold the fuel
pump handle in the fill position.
Fuel Filler Cap
Your fuel tank filler cap has an indexed design with
a 1/8 turn on/off feature.
When fueling your vehicle:
1. Turn the engine off.
2. Carefully turn the filler cap counterclockwise 1/8
of a turn until it stops.
3. Pull to remove the cap from the fuel filler pipe.
4. To install the cap, align the tabs on the cap with
the notches on the filler pipe.
5. Turn the filler cap clockwise 1/8 of a turn until it
stops.
If the ªService Engine Soon/Check Engineº indicator
comes on and stays on when you start the engine,
the fuel filler cap may not be properly installed.
Turn off the engine, remove the fuel filler cap, align
the cap properly and reinstall it.
If you must replace the fuel filler cap, replace
it with a fuel filler cap that is designed for
your vehicle. The customer warranty may be
void for any damage to the fuel tank or fuel
system if the correct genuine Ford or
Motorcraft fuel filler cap is not used.
The fuel system may be under pressure. If
the fuel filler cap is venting vapor or if you
hear a hissing sound, wait until it stops before
completely removing the fuel filler cap. Otherwise,
fuel may spray out and injure you or others.
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161

If you do not use the proper fuel filler cap,
excessive pressure or vacuum in the fuel
tank may damage the fuel system or cause the fuel
system to work improperly in a collision, which
may result in possible personal injury.
Choosing the right fuel
Use only UNLEADED FUEL. The use of leaded fuel
is prohibited by law and could damage your vehicle.
Do not use fuel containing methanol. It can damage
critical fuel system components.
Your vehicle was not designed to use fuel or fuel
additives with metallic compounds, including
manganese-based compounds containing MMT.
Repairs to correct the effects of using a fuel for
which your vehicle was not designed may not be
covered by your warranty.
Octane recommendations
Your vehicle is
designed to use
ªRegularº unleaded
gasoline with an
(R+M)/2 octane rating of 87. We do not recommend
the use of gasolines labeled as ªRegularº that are
sold with octane ratings of 86 or lower in high
altitude areas.
Do not be concerned if your engine sometimes
knocks lightly. However, if it knocks heavily under
most driving conditions while you are using fuel with
the recommended octane rating, see your dealer or
a qualified service technician to prevent any engine
damage.
Fuel quality
If you are experiencing starting, rough idle or
hesitation driveability problems during a cold start,
try a different brand of ªRegularº unleaded gasoline.
87(R+M)/2 METHOD
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162

ªPremiumº unleaded gasoline is not recommended
(particularly in the United States) because it may
cause these problems to become more pronounced.
If the problems persist, see your dealer or a qualified
service technician.
It should not be necessary to add any aftermarket
products to your fuel tank if you continue to use a
high quality fuel.
Cleaner air
Ford approves the use of gasolines to improve air
quality, including reformulated gasolines that contain
oxygenates up to 10% ethanol or 15% MTBE.
Running out of fuel
Avoid running out fuel because this situation may
have an adverse affect on powertrain components.
If you have run out of fuel:
²You may need to crank the engine several times
after refueling before the system starts to pump
the fuel from the tank to the engine.
²Your ªService Engine Soonº indicator may come
on. For more information on the ªService Engine
Soonº indicator, refer to theInstrumentation
chapter.
Fuel Filter
For fuel filter replacement, see your dealer or a
qualified service technician. Refer to the Scheduled
Maintenance Guide for the appropriate intervals for
changing the fuel filter.
Replace the fuel filter with an authorized
Motorcraft part. The customer warranty may
be void for any damage to the fuel system if an
authorized Motorcraft fuel filter is not used.
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163

ESSENTIALS OF GOOD FUEL ECONOMY
Measuring techniques
Your best source of information about actual fuel
economy is you, the driver. You must gather
information as accurately and consistently as
possible. Fuel expense, frequency of fillups or fuel
gauge readings are NOT accurate as a measure of
fuel economy. We do not recommend taking fuel
economy measurements during the first 1 600 km
(1 000 miles) of driving (engine break-in period).
You will get a more accurate measurement after
3 000 km±5 000 km (2 000 miles-3 000 miles).
Filling the tank
The advertised fuel capacity of the fuel tank on your
vehicle is equal to the rated refill capacity of the fuel
tank as listed in theRefill Capacitieschart in this
ªOwner Guide.º The advertised capacity is the
amount of the Indicated Capacity and the Empty
Reserve combined. Indicated Capacity is the
difference in the amount of fuel in a full tank and a
tank when the fuel gauge indicates empty. Empty
Reserve is the small amount of usable fuel remaining
in the fuel tank after the fuel gauge indicates empty.
The amount of Empty Reserve varies and
should not be relied upon to increase driving
range. When refueling your vehicle after the
fuel gauge indicates empty, you might not be
able to refuel the full amount of the advertised
capacity of the fuel tank due to the empty
reserve still present in the tank.
For consistent results when filling the fuel tank:
²Use the same filling rate setting (low Ð medium
Ð high) each time the tank is filled.
²Allow three automatic click-offs when filling.
²Always use fuel with the recommended octane
rating.
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164

²Use a known quality gasoline, preferably a
national brand.
²Use the same side of the same pump and have
the vehicle facing the same direction each time
you fill up.
²Have the vehicle loading and distribution the
same every time.
Your results will be most accurate if your filling
method is consistent.
Calculating fuel economy
1. Fill the fuel tank completely and record the initial
odometer reading (in kilometers or miles).
2. Each time you fill the tank, record the amount of
fuel added (in liters or gallons).
3. After at least three to five tank fill-ups, fill the
fuel tank and record the current odometer reading.
4. Subtract your initial odometer reading from the
current odometer reading.
5. Follow one of the simple calculations in order to
determine fuel economy:
Multiply liters used by 100, then divide by total
kilometers traveled.
Divide total miles traveled by total gallons
used.
Keep a record for at least one month and record the
type of driving (city or highway). This will provide
an accurate estimate of the vehicle's fuel economy
under current driving conditions. Additionally,
keeping records during summer and winter will show
how temperature impacts fuel economy. In general,
lower temperatures give lower fuel economy.
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165

Driving style Ð good driving and fuel economy
habits
Give consideration to the lists that follow and you
may be able to change a number of variables and
improve your fuel economy.
Habits
²Smooth, moderate operation can yield up to 10%
savings in fuel.
²Steady speeds without stopping will usually give
the best fuel economy.
²Idling for long periods of time (greater than one
minute) may waste fuel.
²Anticipate stopping; slowing down may eliminate
the need to stop.
²Sudden or hard accelerations may reduce fuel
economy.
²Slow down gradually.
²Driving at reasonable speeds (traveling at 88 km/h
[55 mph] uses 15% less fuel than traveling at
105 km/h [65 mph]).
²Revving the engine before turning it off may
reduce fuel economy.
²Using the air conditioner or defroster may reduce
fuel economy.
²Using speed control (if equipped) may improve
fuel economy. Speed control can help maintain a
constant speed and reduce speed changes. You
may want to turn off the speed control in hilly
terrain as unnecessary shifting between third and
fourth gears may occur and could result in
reduced fuel economy.
²Warming up a vehicle on cold mornings is not
required and may reduce fuel economy.
²Resting your foot on the brake pedal while driving
may reduce fuel economy.
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166

²Combine errands and minimize stop-and-go
driving.
Maintenance
²Keep tires properly inflated and use only
recommended size.
²Operating a vehicle with the wheels out of
alignment will reduce fuel economy.
²Use recommended engine oil. Refer toLubricant
Specifications.
²Perform all regularly scheduled maintenance
items. Follow the recommended maintenance
schedule and owner maintenance checks found in
your vehicle Scheduled Maintenance Guide.
Conditions
²Heavily loading a vehicle or towing a trailer may
reduce fuel economy at any speed.
²Carrying unnecessary weight may reduce fuel
economy (approximately 2 km/h [1 mpg] is lost
for every 180 kg [400 lb] of weight carried).
²Adding certain accessories to your vehicle (for
example bug deflectors, rollover/light bars,
running boards, ski/luggage racks) may reduce
fuel economy.
²Using fuel blended with alcohol may lower fuel
economy.
²Fuel economy may decrease with lower
temperatures during the first 12±16 km (8±10
miles) of driving.
²Driving on flat terrain offers improved fuel
economy as compared to driving on hilly terrain.
²Transmissions give their best fuel economy when
operated in the top cruise gear and with steady
pressure on the gas pedal.
²Close windows for high speed driving.
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167

EPA window sticker
Every new vehicle should have the EPA window
sticker. Contact your dealer if the window sticker is
not supplied with your vehicle. The EPA window
sticker should be your guide for the fuel economy
comparisons with other vehicles.
It is important to note the box in the lower left
corner of the window sticker. These numbers
represent the Range of Km/L (MPG) expected on
the vehicle under optimum conditions. Your fuel
economy may vary depending upon the method of
operation and conditions.
EMISSION CONTROL SYSTEM
Your vehicle is equipped with various emission
control components and a catalytic converter which
will enable your vehicle to comply with applicable
exhaust emission standards. To make sure that the
catalytic converter and other emission control
components continue to work properly:
²Use only unleaded fuel.
²Avoid running out of fuel.
²Do not turn off the ignition while your vehicle is
moving, especially at high speeds.
²Have the items listed in your Scheduled
Maintenance Guide performed according to the
specified schedule.
The scheduled maintenance items listed in the
Scheduled Maintenance Guide are essential to the
life and performance of your vehicle and to its
emissions system.
If other than Ford, Motorcraft or Ford-authorized
parts are used for maintenance replacements or for
service of components affecting emission control,
such non-Ford parts should be equivalent to genuine
Ford Motor Company parts in performance and
durability.
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168