BLEEDING
INJECTION
SYSTEM
COMPONENTS
• The actual procedure for
bleeding a fuel system
varies from engine
manufacturer to engine
manufacturer, the basics
are pretty much the
same.
• If your engine has a
mechanical-lift fuel pumpthis is the low-pressure
pump that's attached to
the engine-it will often be
equipped with a small
lever that lets you pump
fuel without turning on
the engine.
Open/Loosen the Fuelline Unions
• To purge air from the lowpressure side of the fuel
system, open fuel-line unions
and bleed ports downstream
of the pump, one at a time,
beginning with those closest
to the pump, and continue
pumping until fuel, and not
air, runs out.
• Then you must bleed the
high-pressure fuel system,
which is done by loosening
the union nuts between the
top of the fuel injectors
and the fuel line; it just
takes a turn or two.
• Once loosened, use the
starter to crank the engine
for 10 seconds. If fuel fails to
make an appearance at the
unions, wait 60 seconds (to
allow the starter to cool),
then crank again for 10
seconds. The process could
require several repetitions
until fuel dribbles out.
• When it does, tighten the
unions and crank the
engine with the throttle
advanced 25 percent. It
should catch, although it
may run rough at first.
Advance or retard the
throttle until the engine
begins to run smoothly.
Open/Loosen the Fuel
Filter Bleeder Screw
• The fuel system's secondary or
on-engine fuel filter is located
between the lift pump and the
high-pressure injection pump,
and it's here that air often
becomes trapped. Most
secondary fuel filters are
equipped with a bleed screw.
Opening this and working the liftpump lever until a clear stream
of fuel flows out means that
you've successfully bled the
system up to that point.
Loosen the Injection
Pump Bleeder Screw
• As the injection pump
bleeder screw is loosen
up. Pump the manual
pump until air comes
out.
Note Caution:
• If you must crank the engine for
more than about 20 seconds, close
the cooling-water intake seacock.
Each time the engine is cranked, it
pumps water into the exhaust
system, and until the engine starts,
the water will accumulate there.
Eventually, it can reach the exhaust
manifold, exhaust valves, and
ultimately the cylinders, causing
extensive damage. Remember,
however, to open the seacock once
the engine begins to run.