Air In The Fuel System - Dodge D250 1990 Service Manual

Fuel System Malfunction - Diagnosis
Page 14-4
Fuel System
DODGE Turbo Diesei
Air In the Fuel System
A replacement of supply lines, fuel filters, injection pump, high
pressure lines and injectors will let air enter the fuel system.
Follow the specified procedure to bleed the air from the
system.
Since the lift pump and injection pump provide a positive
pressure through the fuel filter and supply line to the injection
pump, loose connections or defective seals will show as a fuel
leak.
The most usual place for air to enter the fuel system is between
the inlet of the lift pump and the suction tube in the tank. The
fuel tank has the outlet fitting at the top with a suction tube that
extends down in the tank. Cracks or pin holes in the tube to the
fitting can let air enter the fuel system.
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Air in the system will make the engine: hard to start, run rough,
misfire, produce low power, and can cause excessive smoke
and a fuel knock.