GMC 2003 C4C042, Owner'S Manual

Page: 265 / 386

6-11
Q:
How does air get into the fuel lines?
A:
One of the following may have happened:
D The vehicle ran out of fuel, or
D The fuel filter was removed for servicing or
replacement, or
D The fuel lines were removed or disconnected for
servicing, or
D The fuel filter water drain valve was opened while
the engine was running.
If one or more of the above occur, it is very likely that
air has entered your fuel system and that you will need
to prime the fuel system before operating the vehicle.
Air in the fuel lines will not harm the engine or
the vehicle.
However, the engine may not be able to start until the
fuel system is primed and the air is removed.
Q:
How do I prime the vehicle?
A:
Your vehicle is equipped with a priming pump
which is part of the engine mounted fuel filter.
The vent valve and the fuel filter primer pump
are located on top of the fuel filter housing. The
priming pump is hand operated and is designed to
bring fuel to the engine to eliminate any air that
may be in the fuel lines.
To prime the engine, do the following:
1. Make sure there is fuel in the tank.
2. Make sure the fuel filter had been installed and
properly tightened.
3. Make sure the fuel lines are properly connected and
the fuel filter is cool enough to touch.
4. Remove any dirt from the fuel filter head and vent
valve by wiping with a cloth.