GMC 1994 Yukon Owner's Manual page 130

Gages
Fuel Gage
Standard Cluster -Gas Standard Cluster -Diesel
DIESEL FUEL ONLY
Tachometer Cluster -Gas Tachometer Cluster -Diesel
The fuel gage, when the ignition is on, tells you about how much fuel you
have left in your tank. The gage will first indicate empty before you are out
of fuel, and you should get more fuel as soon as possible.
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