GMC 2007 Yukon XL Owner's Manual page 139

2. If the engine does not start within 10 seconds,
push the accelerator pedal all the way to the
floor, while you hold the ignition key in
START. When the engine starts, let go of the
key and let up on the accelerator pedal.
Wait about 15 seconds between each try.
When starting your engine in very cold weather
(below 0°F or 18°C), do this:
1. With your foot off the accelerator pedal, turn
the ignition key to START and hold it there up
to 15 seconds. When the engine starts, let
go of the key.
2. If your engine still will not start, or starts but
then stops, it could be flooded with too much
gasoline. Try pushing your accelerator
pedal all the way to the floor and holding it
there as you hold the key in START for about
three seconds.
When the engine starts, let go of the key and
accelerator. If the vehicle starts briefly but then
stops again, do the same thing, but this time
keep the pedal down for five or six seconds.
This clears the extra gasoline from the engine.
Notice: Your engine is designed to work with
the electronics in your vehicle. If you add
electrical parts or accessories, you could
change the way the engine operates. Before
adding electrical equipment, check with
your dealer. If you do not, your engine might
not perform properly. Any resulting damage
would not be covered by your vehicle's
warranty.
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