GMC C series 2002 Owner's Manual page 120

When the ignition is on, your fuel gage lets you know
about how much fuel you have left. When the gage first
shows empty, you'll still have a little fuel left, but you
should get more fuel soon.
If your vehicle has dual fuel tanks, the reading on the
gage is the average of the two tanks.
Here are four concerns of some operators. None of these
shows a problem with your fuel gage:
D
The gage moves a little when you turn a corner or
speed up.
D
The gage doesn't go back to empty when you turn
off the ignition.
D
At the gas station, the pump shuts off before the gage
reads full.
D
It takes a little more or less fuel to fill up than the
gage indicated.
If you have a diesel engine, also see your Caterpillar
Operation& Maintenance Manual.
Air Pressure Gage (If Equipped)
If the needle on the gage indicates that the air pressure is
below 60 psi (415 kPa), the LOW AIR warning light
will come on. An alarm will also sound if this happens.
The yellow pointer shows the pressure available for the
front system, while the green pointer shows pressure for
the rear. There should be no more than 4 psi (28 kPa)
difference showing between the systems.
Don't drive until both pointers are showing at least
120 psi (830 kPa), so you'll have enough air if you
need to apply your brakes.
If your vehicle has air
brakes, this gage at the
center of your instrument
panel cluster shows the air
pressure for both your front
and rear brake systems.
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