2004 JEEP GRAND CHEROKEE fuel pressure

Defrosters
Check operation by selecting the defrost mode and place
the blower control on high speed. You should feel the air
directed against the windshield.
Safety Checks You Should Make Outside The
Vehicle
Tires
Examine tires for excessive tread wear or uneven wear
patterns. Check for stones, nails, glass, or other objects
lodged in the tread. Inspect for tread cuts or sidewall
cracks. Check wheel nuts for tightness and tires (includ-
ing spare) for proper pressure.
Lights
Have someone observe the operation of all exterior lights
while you work the controls. Check turn signal and high
beam indicator lights on the instrument panel.
Fluid Leaks
Check area under vehicle after overnight parking for fuel,
coolant, oil or other fluid leaks. Also, if gasoline fumes
are detected, the cause should be located and corrected
immediately.
THINGS TO KNOW BEFORE STARTING YOUR VEHICLE 53
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7. Oil Pressure Gage
Indicates the engine oil pressure. This gage does
not measure oil level. Pressure varies with engine
speed, temperature, and oil viscosity. Normal oil pressure
will be midway between the lowest and highest limit
marks.
8. Sentry Key Indicator Light Ð If Equipped
Refer to ªSentry Key Immobilizer Systemº in
Section 2 of this manual for more information.
9. Malfunction Indicator Light
This light is part of an onboard diagnostic system
called OBD II which monitors engine and auto-
matic transmission control systems. This light
will illuminate when the ignition is in the ON position
before engine start. If the bulb does not come on when
turning the ignition key from OFF to ON, have the
condition checked promptly.Certain conditions such has a loose or missing gas cap,
poor fuel quality, etc. may illuminate the light after
engine start. The vehicle should be serviced if the light
stays on through several typical driving cycles. In most
situations, the vehicle will drive normally and will not
require towing.
When the engine is running, the ªMalfunction Indicator
Lightº may flash to alert of serious conditions that could
lead to immediate loss of power or severe catalytic
converter damage. The vehicle should be serviced as
soon as possible if this occurs.
10. Cruise Indicator Light
This indicator lights when the electronic speed
control system is turned ON.
11. Check Gages Warning Light
This light illuminates when the voltmeter, oil
pressure, or temperature gages indicate a reading
130 UNDERSTANDING YOUR INSTRUMENT PANEL

either too high or too low. Examine the gages carefully,
and follow the instructions above for each indicated
problem.
NOTE:When the ignition switch is turned to OFF, the
fuel gage, voltmeter, oil pressure, and temperature gages
will not show any readings. When the engine is not
running, turn the ignition switch to ON to obtain accu-
rate readings.
12. Part Time Indicator Light
This light alerts the driver that the vehicle is in
the PART TIME four±wheel drive mode, and
the front and rear driveshafts are mechanically
locked together forcing the front and rear wheels to rotate
at the same speed.
13. Transmission Over Temperature Warning Light
This light indicates that there is excessive transmis-
sion fluid temperature that might occur with severe
usage such as trailer towing or snow plowing. If this lightcomes on, stop the vehicle and run the engine at idle or
faster, with the transmission in N (Neutral) until the light
goes off.
14. Temperature Gage
Indicates engine coolant temperature. Any read-
ing within the normal range indicates that the
cooling system is operating satisfactorily.
The gage pointer will likely indicate a higher temperature
(above center scale) when driving in hot weather, up
mountain grades, or when towing a trailer. It should not
be allowed to exceed the upper limits of the normal
operating range.
If the pointer rises to the 260É (Hot) mark, pull over and
stop the vehicle. Do not turn the engine off. Idle the
vehicle with the air conditioning turned off, until the
pointer drops back into the normal range.
UNDERSTANDING YOUR INSTRUMENT PANEL 131
4

NTire Spinning........................214
NTread Wear Indicators..................215
NReplacement Tires.....................215
NAlignment And Balance.................217
mTire Pressure Monitor System Ð If Equipped . . . 217
NTire Pressure Monitor System Tire/Wheel
Rotation And Sensor Replacement Ð If
Equipped...........................218
NGeneral Information...................219
mTire Chains...........................220
mTire Rotation Recommendations............220
mFuel Requirements......................221
NReformulated Gasoline.................222
NGasoline/Oxygenate Blends..............222NMMT In Gasoline.....................223
NSulfur In Gasoline.....................223
NMaterials Added To Fuel................224
mFuel Tank Filler Cap (Gas Cap).............224
mTrailer Towing.........................226
NTrailer And Tongue Weight..............228
NCooling System TipsÐTrailer Towing.......229
NMinimum Vehicle Requirements For Trailer
Towing............................230
mRecreational Towing (Behind Motorhome, Etc.) . . 231
NShifting Into Neutral (N)................232
NShifting Out Of Neutral (N)..............233
mSnow Plow...........................234
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5

2. EconomyÐ
Improper inflation pressures can cause uneven wear
patterns to develop across the tire tread. These abnormal
wear patterns will reduce tread life resulting in a need for
earlier tire replacement. Under inflation also increases
tire rolling resistance and results in higher fuel consump-
tion.
3. Ride Comfort and Vehicle StabilityÐ
Proper tire inflation contributes to a comfortable ride.
Over inflation produces a jarring and uncomfortable ride.
Both under inflation and over inflation affect the stability
of the vehicle and can produce a feeling of sluggish
response or over responsiveness in the steering.
Unequal tire pressures can cause erratic and unpredict-
able steering response.
Unequal tire pressure from side to side may cause the
vehicle to drift left or right.Tire Inflation Pressures
The proper cold tire inflation pressure for passenger cars
is listed on either the face of the driver's door or the
driver's side ªBº pillar. For vehicles other than passenger
cars, the cold tire inflation pressures are listed on either
the ªBº pillar or the Certification Label.
212 STARTING AND OPERATING

Tread Wear Indicators
These indicators are narrow strips 1/16 inch (1.6 mm)
thick and are found in the tread pattern grooves.
When the tread pattern is worn down to these treadwear
indicators, the tires should be replaced.
Overloading your vehicle, long trips in very hot weather,
and driving on bad roads may result in greater wear.
Replacement Tires
The tires on your new vehicle provide a balance of many
characteristics. They should be inspected regularly for
wear and correct inflation pressure. The manufacture
strongly recommends that you use tires equivalent to the
originals in quality and performance when replacement
is needed (see section on tread wear indicators). Failure
to use equivalent replacement tires may adversely affect
the safety, handling, ride and fuel economy of your
vehicle. We recommend that you contact your original
equipment tire dealer on any questions you may have on
tire specifications or capability.
STARTING AND OPERATING 215
5

NOTE:The Tire Pressure Monitor system must be
retrained following a tire rotation. See your authorized
dealer for service.
The suggested rotation method is the ªforward-crossº
shown in the following diagram.FUEL REQUIREMENTS
Your engine is designed to meet all emis-
sions regulations and provide excellent
fuel economy and performance when us-
ing high quality unleaded gasoline having
an octane rating of 87. The use of premium
gasoline is not recommended. The use of
premium gasoline will provide no benefit over high
quality regular gasoline, and in some circumstances may
result in poorer performance.
NOTE: 4.7L HO Engines (If Equipped): High quality
premium unleaded gasoline with an octane rating of 91
is recommended but not required.
Light spark knock at low engine speeds is not harmful to
your engine. However, continued heavy spark knock at
high speeds can cause damage and immediate service is
required. Engine damage resulting from operation with a
heavy spark knock may not be covered by the new
vehicle warranty.
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CAUTION!
Damage to the fuel system or emission control
system could result from using an improper fuel
tank filler cap (gas cap). A poorly fitting cap could let
impurities into the fuel system.
WARNING!
²Remove the fuel cap slowly to prevent fuel spray
from the filler neck which may cause injury.
²The volatility of some gasoline may cause a
buildup of pressure in the fuel tank which may
increase while you drive. This pressure can result
in a spray of gasoline and/or vapors when the cap
is removed from a hot vehicle. Removing the cap
slowly allows the pressure to vent and prevents
fuel spray.
²Never add fuel when the engine is running.
²Never have any smoking materials lit in or near
the vehicle when the fuel cap is removed or the
tank filled.
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