1999 GMC C-SERIES fuel pump

yellowblue
2-68 Fuel Gage
Gasoline Engine Diesel Engine
Your fuel gage will be on the right side of your
instrument cluster if your vehicle doesn't have the
optional tachometer. If you have a tachometer, your
fuel gage is on the lower left portion of your
instrument cluster.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:

The gage moves a little when you turn a corner or
speed up.

The gage doesn't go back to empty when you turn
off the ignition.

At the gas station, the pump shuts off before the gage
reads full.

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.
ProCarManuals.com

yellowblue
6-5
To provide cleaner air, all gasolines in the United States
are now required to contain additives that will help
prevent deposits from forming in your engine and fuel
system, allowing your emission control system to
function properly. Therefore, you should not have to add
anything to the fuel. In addition, gasolines containing
oxygenates, such as ethers and ethanol, and
reformulated gasolines may be available in your area to
contribute to clean air. General Motors recommends that
you use these gasolines, particularly if they comply with
the specifications described earlier.
NOTICE:
Your vehicle was not designed for fuel that
contains methanol. Don't use it. It can corrode
metal parts in your fuel system and also damage
plastic and rubber parts. That damage wouldn't
be covered under your warranty.
Diesel Fuel Requirements and
Fuel System
Diesel Engine Fuel
See your Caterpillar
Operator & Maintenance Manual
for information concerning fuel usage.
Water in Fuel
Sometimes, water can be pumped into your fuel tank
along with your diesel fuel. This can happen if a service
station doesn't regularly inspect and clean its fuel tanks,
or if it gets contaminated fuel from its suppliers.
If this happens, water must be drained. Your dealer can
show you how to do this.
CAUTION:
Diesel fuel containing water is still flammable.
You could be burned. If you ever try to drain
water from your fuel, keep sparks, flames and
smoking materials away from the mixture.
ProCarManuals.com

yellowblue
6-8
NOTICE:
If you need a new cap, be sure to get the right
type. Your dealer can get one for you. If you get
the wrong type, it may not fit or have proper
venting, and your fuel tank and emissions system
might be damaged.
If you have dual tanks, fill the driver's side first. The
fuel gage will give better readings this way. Your gage
will show the average level of both tanks combined.
Filling a Portable Fuel Container
CAUTION:
Never fill a portable fuel container while it is in
your vehicle. Static electricity discharge from the
container can ignite the gasoline vapor. You can
be badly burned and your vehicle damaged if this
occurs. To help avoid injury to you and others:

Dispense gasoline only into
approved containers.

Do not fill a container while it is inside a
vehicle, in a vehicle's trunk, pickup bed or
on any surface other than the ground.

Bring the fill nozzle in contact with the
inside of the fill opening before operating
the nozzle. Contact should be maintained
until the filling is complete.

Don't smoke while pumping gasoline.
ProCarManuals.com

yellowblue
6-70
Name Circuits Protected
HYD BRK Brake Pump Motor Relay
HYD BRK Brake Alarm ModuleName Circuits Protected
B/U IGN3 Fuel Filter Relay, Blower Motor
Relays, ABS Power Relay,
Back
-Up Lamps, Auxiliary Wiring
Relay, IGN 3 Relay, Power
Window Relay, Vehicle Interface
Module, Transmission
Temperature Gage
STOP Stoplamps
WASH/WIPE Windshield Wipers/Washer,
Accessory Relay
DOME/PNL Dome Lamp, Radio Receiver,
Instrument Panel Lights,
A/C Controller,
Headlamp/Seatbelt Module
BLOWER Blower Motor
A/C A/C Clutch Compressor,
A/C Controller
TRN/HAZ Turn Signals, Hazard Flashers
ProCarManuals.com

yellowblue
6-71
Name Circuits Protected
CHAS Exhaust Brake, Air Suspension
Dump Valve, Air Dryer, HYD
ABS ECHU
PARK LP Auxiliary Wiring, Air Conditioner
Controls, Parking Lamps, Turn
Signals, Taillamps, Stoplamps,
Marker Lamps, Trailer Running
Lamps, Lighted Mirrors, Radio
Receiver, Mirror Clearance Lamps
HORN Horn/Diagnostic Connector
PRK BRK Parking Brake Module
FUEL Heated Fuel Filter (Diesel
Engines) or Fuel Pump
(Gasoline Engines)
AXLE Heated Mirrors, Radiator Shutters,
Tw o
-Speed Axle Motor,
Tw o
-Speed Axle Switch
MRKR LP Roof Marker Lamps,
Trailer Marker Lamps,
Marker Lamp RelayName Circuits Protected
CIG/AUX Cigarette Lighter,
Auxiliary Power Jacks
AUX Auxiliary Wiring Relay
IGN RLY/VIN Vehicle Interface Module
(Diesel Engines) or Generator,
Coil, Injectors (Gasoline Engines)
WDO Power Windows
CRNK Starter Relay
IGN SW Instrument Panel Cluster Telltales
AUX Auxiliary Wiring
RDO Radio, Auxiliary Wiring
DR LK Power Door Locks
ProCarManuals.com

yellowblue
6-73
Name Circuits/Circuit Breakers
Protected
STP/HAZ
TURNStop Lamp, Turn Signal/Hazard
Lights, Fuel, Ignition Relay
(Gasoline Engines)
IGN SW3 Air Conditioner, Ignition Switch,
Axle, ChassisName Circuits/Circuit Breakers
Protected
INT/EXT
LIGHTSParking Lamps,
Dome/Panel Lights
HEAD LAMP Headlamps,
Daytime Running Lamps
AUX WRG Auxiliary, Park Brake
IGN SW1 Ignition Switch, Wash/Wipe,
Crank, Radio
HYD PUMP Hydraulic Brake,
Brake Pump Motor
HYD ABS EHCU
PWR
WDO/LCKSWindow, Door Locks
PARK BRK Parking Brake Motor
BLOWER
HORNBlower, Horn, Cigarette
Lighter/Auxiliary
FUEL/ENGINE Empty
ProCarManuals.com