Diagnosis And Testing; General Information - Ford VSG-411 Service Manual

03-4
Fuel System
03-4
DIAGNOSIS AND TESTING
General Information
Water and dirt that accumulate in the fuel tank can cause a
restricted fuel line or filter and malfunction of the fuel pump
or carburetor. Condensation, which is the greatest source
of water entering the fuel tank, is formed by moisture in the
air when it strikes the cold interior walls of the fuel tank.
If the accumulation of dirt and water in the filter is excessive,
the fuel tank should be removed and flushed, and the line
from the fuel pump to the tank should be blown out.
Air leakage in the fuel inlet line can cause low fuel pump
pressure and volume.
A restricted fuel tank vent can cause low fuel pump
pressure and volume and can result in collapsed inlet
hoses or a collapsed fuel tank.
High or low pressure are the two most likely fuel pump
troubles that will affect engine performance. Low pressure
will cause a lean mixture and fuel starvation at high speeds
and excessive pressure will cause high fuel consumption
and carburetor flooding.
Dirt accumulation in the fuel and air passages, improper
idle adjustments, and improper fuel level are the major
sources of carburetor troubles.