Chevrolet Silverado 2007 Owner's Manual page 142

Starting Procedure
1. With your foot off the accelerator pedal, turn
the ignition key to START. When the engine
starts, let go of the key. The idle speed will go
down as your engine gets warm. Do not race
the engine immediately after starting it.
Operate the engine and transmission gently
to allow the oil to warm up and lubricate all
moving parts.
Your vehicle has a Computer-Controlled
Cranking System. This feature assists in
starting the engine and protects components.
If the ignition key is turned to the START
position, and then released when the engine
begins cranking, the engine will continue
cranking for a few seconds or until the vehicle
starts. If the engine does not start and the key
is held in START for many seconds, cranking
will be stopped after 15 seconds to prevent
cranking motor damage. To prevent gear
damage, this system also prevents cranking if
the engine is already running. Engine cranking
can be stopped by turning the ignition switch
to the ACCESSORY or LOCK position.
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Notice: Cranking the engine for long periods
of time, by returning the key to the START
position immediately after cranking has ended,
can overheat and damage the cranking
motor, and drain the battery. Wait at least
15 seconds between each try, to let the
cranking motor cool down.
2. If the engine does not start after 5-10 seconds,
especially in very cold weather (below 0°F
or −18°C), it could be flooded with too much
gasoline. Try pushing the accelerator pedal all
the way to the floor and holding it there as you
hold the key in START for up to a maximum of
15 seconds. Wait at least 15 seconds between
each try, to allow the cranking motor to cool
down. When the engine starts, let go of the
key and accelerator. If the vehicle starts briefly
but then stops again, do the same thing. This
clears the extra gasoline from the engine. Do
not race the engine immediately after starting
it. Operate the engine and transmission gently
until the oil warms up and lubricates all moving
parts.