Service Manual

Air in Fuel ISB, ISBe and QSB (Common Rail [...]
Page 6-6 Section 6 - Injectors and Fuel Lines - Group 06
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If air continues to bubble through the clear hose for
several minutes, then an air leak is present.
This test checks for air leaks in the fuel supply lines. If all
components are functioning properly, the fuel lines after
the lift pump will always have a positive pressure. Any
poor connections in lines will result in an external leak and
not air in the fuel.
NOTE: This tool does not contain an orifice and will result
in maximum flow from the lift pump. This will cause
maximum fuel inlet vacuum and will make air leaks and
inlet restriction easier to identify.
Install the M10 male Compucheck™ quick-connect fitting,
Part Number 3824842, on the diagnostic port of the inlet
side of the fuel filter head.
Connect the Compucheck™ quick-connect coupling, Part
Number 3376859, to the Compucheck™ quick-connect
fitting.
Attach a hose to the outlet of the tool.
Collect fuel flow from the hose in a bucket or similar
container.
CAUTION
Use caution when disconnecting or removing fuel
lines, replacing filters and priming the fuel system,
that fuel is not spilled or drained into the bilge area.
Do not drop or throw filter elements into the bilge
area. The fuel and fuel filters must be discarded in
accordance with local environmental regulations.
NOTE: On Marine applications the fuel filter head bracket
is located on the front of the cylinder head. Refer to
Procedure Procedure 100-002 for component location.