1999 FORD MUSTANG fuel cap

Service engine soon
Your vehicle is equipped
with a computer that
monitors the engine's
emission control system.
This system is
commonly known as the On Board Diagnostics System
(OBD II). The OBD II system protects the environment
by ensuring that your vehicle continues to meet
government emission standards. The OBD II system
also assists the service technician in properly servicing
your vehicle.
TheService Engine Soonindicator light illuminates
when the ignition is first turned to the ON position
to check the bulb. If it comes on after the engine is
started, one of the engine's emission control systems
may be malfunctioning. The light may illuminate
without a driveability concern being noted. The
vehicle will usually be drivable and will not require
towing.
What you should do if the Service Engine Soon
light illuminates
Light turns on solid:
This means that the OBD II system has detected a
malfunction.
Temporary malfunctions may cause yourService
Engine Soonlight to illuminate. Examples are:
1. The vehicle has run out of fuel. (The engine may
misfire or run poorly.)
2. Poor fuel quality or water in the fuel.
3. The fuel cap may not have been properly installed
and securely tightened.
These temporary malfunctions can be corrected by
filling the fuel tank with good quality fuel and/or
properly installing and securely tightening the gas
cap. After three driving cycles without these or any
other temporary malfunctions present, theService
Engine Soonlight should turn off. (A driving cycle
SERVICE
ENGINE
SOON
Instrumentation
8

Optional instrument cluster gauges
Fuel gauge
Displays approximately
how much fuel is in the
fuel tank (when the
key is in the ON
position). The fuel gauge may vary slightly when the
vehicle is in motion. The ignition should be in the
OFF position while the vehicle is being refueled.
When the gauge first indicates empty, there is a
small amount of reserve fuel in the tank. When
refueling the vehicle from empty indication, the
amount of fuel that can be added will be less than
the advertised capacity due to the reserve fuel.
Engine coolant temperature gauge
Indicates the
temperature of the
engine coolant. At
normal operating
temperature, the needle remains within the normal
area (the area between the ªHº and ªCº). If it enters
the red section, the engine is overheating. Stop the
vehicle as soon as safely possible, switch off the
engine immediately and let the engine cool. Refer to
Engine coolantin theMaintenance and care
chapter.
P! BRAKE
0
00000 00
FH
H
102040608020 40608010 012 0 14 0
160
180
200
220
240
100
120
140
305070 90
110
13 0
1504
5
6
7
8 3
2
1
H
THEFT
RPMX1000
FUEL DOORSELECT/RESET
LOW
FUELO/D
OFF AIR
BAGSERVICE
ENGINE
SOON
MPH km/h
ABS
.
L
L
F
CH
Instrumentation
12

Never remove the coolant reservoir cap
while the engine is running or hot.
This gauge indicates the temperature of the engine
coolant, not the coolant level. If the coolant is not at
its proper level the gauge indication will not be
accurate.
Speedometer
Indicates the current vehicle speed.
²Base instrument
cluster
²Optional instrument
cluster
Odometer
Registers the total
kilometers (miles) of
the vehicle.
10 203020 406080100
120
140
160
180
405060 70
80
90
100
11 0
120
FUEL DOOR MPH km/h
102040608020 40608010 012 0 14 0
160
180
200
220
240
100
120
140
305070 90
110
13 0
150
FUEL DOOR MPH km/h
0
00000 00
4
5
6
7
8 3
2
1RPMX1000
SELECT/RESET
.
Instrumentation
13

Batteries normally produce explosive gases
which can cause personal injury. Therefore,
do not allow flames, sparks or lighted substances
to come near the battery. When working near the
battery, always shield your face and protect your
eyes. Always provide proper ventilation.
When lifting a plastic-cased battery,
excessive pressure on the end walls could
cause acid to flow through the vent caps, resulting
in personal injury and/or damage to the vehicle or
battery. Lift the battery with a battery carrier or
with your hands on opposite corners.
Keep batteries out of reach of children.
Batteries contain sulfuric acid. Avoid contact
with skin, eyes or clothing. Shield your eyes when
working near the battery to protect against
possible splashing of acid solution. In case of acid
contact with skin or eyes, flush immediately with
water for a minimum of 15 minutes and get
prompt medical attention. If acid is swallowed, call
a physician immediately.
Because your vehicle's engine is electronically
controlled by a computer, some control conditions
are maintained by power from the battery. When the
battery is disconnected or a new battery is installed,
the engine must relearn its idle and fuel trim
strategy for optimum driveability and performance.
To begin this process:
1. Set your parking brake.
2. Put the gearshift in P (Park) (automatic
transmission) or the neutral position (manual
transmission), turn off all accessories and start the
engine.
3. Let the engine idle for at least one minute.
Maintenance and care
151

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.
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.
Automotive fuels can cause serious injury or
death if misused or mishandled.
Observe the following guidelines when handling
automotive fuel:
²Extinguish all
smoking materials
and any open flames
before fueling your
vehicle.
²Always turn off the
vehicle before
fueling.
²Automotive 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.
²Avoid 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.
Maintenance and care
159

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.
Maintenance and care
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
Maintenance and care
162

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.
Maintenance and care
164