Fuel System General Description; Fuel System Identification; Fuel System Diagnosis And Testing; Air Cleaner Description And Operation - Ford VSG-411 Service Manual

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Fuel System
3-01
PART 3 Fuel System
COMPONENT INDEX
GENERAL DESCRIPTION .................
IDENTIFICATION ..........................
DIAGNOSIS AND TESTING ................
General Information .....................
AIR CLEANER ............................
Description and Operation ................
Removal and Installation
.................
FUEL PUMPS ............................
Description .............................
Diagnosis and Testing ....................
REMOVAL AND INSTALLATION ............
Fuel Pump Assembly ....................
FACET CARBURETOR ....................
Disassembly ............................
Cleaning and Inspection
..................
Assembly ...............................
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COMPONENT INDEX Page
SIDEDRAFT 870MODEL CARBURETOR
..... 3-04
Description ............................. 3-04
Operation .............................. 3-06
Disassembly ............................ 3-07
Cleaning ...............................
3-07
Inspection .............................. 3-07
Reassembly ............................ 3-08
Special Tools Required
................... 3-08
VARIABLE VENTURI CARBURETOR
........ 3-10
Description
.............................
3-10
Operation
.............................. 3-I 0
DIAGNOSTIC CHECKS AND
ADJUSTMENTS
.......................... 3-I 7
Idle Fuel Mixture and Idle Speed .......... 3-17
REMOVAL AND INSTALLATION ............ 3-18
V. V. Carburetor ......................... 3-18
GENERAL DESCRIPTION
The fuel system includes a thermostatically controlled air clean-
er with a dry element and a permanently sealed single action fuel
pump operated by a lobe on the camshaft and a single barrel
variable venturi carburetor with a manual choke. It also has a
screen filter located in the fuel inlet.
I
1
IDENTIFICATION
The carburetor is identified on the main body near the fuel inlet.
The basic part number for all carburetors is 95 10. To procure
84BF - KJA
PART NO. PREFIX PART NO. SUFFIX
parts, it is necessary to know the part number prefix and suffix
I
I
(Figure 1).
FIG. 1 Carburetor Identification - Typical
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 exces-
sive, 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.
AIR CLEANER
DESCRIPTION AND OPERATION
The thermostatically controlled air cleaner has two sources of
air supply, the cool air from the front of the engine compartment
and hot air from a heat box mounted on the exhaust manifold. The
air supply through the air cleaner is controlled by a duct valve
mounted on the cleaner spout. The duct valve blends cool air and
hot air to achieve the required air intake temperature.
The duct valve is operated by a vacuum diaphragm unit which
holds it fully open as long as vacuum is maintained above approx-
imately 100 mm (4.0 in. ) of mercury. Under these conditions only
hot air from the exhaust manifold is allowed to enter the air
cleaner.
As the vacuum applied to the diaphragm unit falls below ap-
proximately 100 mm (4.0 in.) of mercury the valve progressively
closes allowing cooler air to enter the air cleaner. This action
continues until the vacuum is reduced to approximately 50 mm
(2.0 in.) of mercury, at which time only cool air from the standard
intake enters the air cleaner. The vacuum feed for the diaphragm
unit is supplied from the intake manifold via a heat sensor.
The heat sensor unit is located inside the air cleaner and senses
the temperature of the air actually entering the carburetor. The unit
consists of two vacuum take off points, a bi-metal strip and a ball
valve. When the air flow past the sensor is cold the ball valve in the