GMC 2003 C4C042 Owner's Manual page 309

Primary Fuel Filter and Water Separator
(If Equipped)
It has a clear plastic drain bowl at the bottom. Check the
drain bowl occasionally for any water or particles.
To drain the bowl, do the following:
1. Shut off the engine.
2. Partially open the drain valve at the bottom of
the filter.
See "Engine Oil" in the Index for proper disposal
procedures.
If you have a diesel engine,
-
you may have this spin on
filter. It is located on the
driver's side frame rail.
Secondary Fuel Filter and Water
Separator/Heater (If Equipped)
It has a metal drain bowl at the bottom. Occasionally,
check the bowl for any water or particles.
To check or drain the bowl, do the following:
D
Shut off the engine.
D
Push up on the spring loaded drain valve until clear
fuel is flowing from the valve.
The particles or water will drain out first. See "Engine
Oil" in the Index for proper disposal procedures.
R
If you have a Caterpillar
diesel engine, you may also
-
have this spin on filter and
fuel separator/heater. It will
be mounted in the engine
compartment on the driver's
side of the vehicle.
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