GMC Duramax Diesel 2015 Owner's Manual page 59

9-32 Driving and Operating
5. Locate the fuel filter vent valve
on top of the fuel filter housing.
Turn the valve screw
counterclockwise several full
turns to open.
6. Locate the fuel filter priming
pump on top of the fuel filter
housing. Push down and let it
return up several times.
7. Continue priming the pump until
a small amount of fuel comes
from the vent valve. This
indicates the filter is full of fuel
and the system should be
primed.
8. Close the vent valve. Clean any
fuel off the fuel filter. Try to start
the engine. If the engine stalls,
operate the priming pump
several times in between starting
attempts. Allow the engine to
idle for a few minutes after it
starts. Check the filter for leaks.
To Prime Van Models
There is an electric priming pump
that will bring fuel to the engine and
eliminate air in the fuel lines. To
prime the engine:
1. Correct any condition that
caused the loss of prime.
2. Turn the ignition to ON/RUN for
30 seconds. Do not start the
engine. The fuel pump will start
priming.
3. Turn the ignition off, then back to
start, and crank the engine for
15 seconds.
4. If the engine does not start,
repeat Steps 2 and 3 until the
engine starts.
If the engine does not start after
repeating Steps 2 and 3 three
times, turn the ignition key off for
60 seconds.