Fuel Pump; Description; Diagnosis And Testing; Pressure Tests - Ford VSG-411 Service Manual

03-5
Fuel Svstem
03-5
FUEL PUMP
Description
A single action mechanical fuel pump is standard on this
engine. It is located on the right side of the engine and is
driven by a lobe on the camshaft.
The pump is permanently sealed and is serviced by
replacing the entire unit.
Diagnosis and Testing
To determine that the fuel pump is in satisfactory operating
condition, tests for both fuel pump pressure and fuel pump
capacity (volume) should be performed.
The tests are performed with the fuel pump installed on the
engine and the engine at normal operating temperature at
idle speed.
Before the tests, make sure the replaceable fuel filter
has been changed within the recommended
maintenance mileage interval. When in doubt, install a
new filter.
Pressure Tests
Refer to the fuel pump specification and note the fuel pump
pressure and capacity (volume) design tolerances.
1. Remove the air cleaner assembly. Disconnect the fuel
inlet line or the fuel filter at the carburetor. Use care
to prevent combustion due to fuel spillage.
2.
Connect pressure gauge, restrictor and flexible hose
between the fuel filter and carburetor.
NOTE: Inside diameter of smallest passage in test
flow circuit must not be smaller than 5.59 mm (0.220
in).
3.
Position the flexible fuel outlet hose and the restrictor
so the fuel can be discharged into the graduated
container.
4. Before taking a pressure reading operate the engine
at the specified idle rpm and vent the system into the
container by opening the hose restrictor momentarily.
5. Close the hose restrictor, allow the pressure to
stabilize, and note the reading.
If the pump pressure is not within specifications with
temperatures normalized at idle speed and in neutral and
the fuel lines and filter are in satisfactory condition, the
pump is worn or damaged and should be replaced.
If the pump pressure is within specifications, perform the
tests for fuel capacity (volume).
Capacity (Volume) Test
With the fuel pump pressure within specifications, test the
capacity (volume) as follows:
1.
Operate the engine at the specified idle rpm.
2. Open the hose restrictor and expel the fuel into the
container, while observing the time required to expel
0.5 liters (one pint). Close the restrictor. 0.5 liters (one
pint) or more of fuel should be expelled within the
specified time limit (25 sec.).
If the pump volume is below specifications, repeat the test
using an auxiliary fuel supply and a new fuel filter. If the
pump volume meets specifications while using the auxiliary
fuel supply, check for a restriction in the fuel supply from
the tank and for the tank not venting properly.