Hudson 1948 - 1952, Service Manual

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diaphragm (I) up against the diaphragm spring (J), expel-
ling air through the outlet valve (K) and port (L) into the
manifold.
With the cam lever on the low side of the eccentric, spring
pressure forces the diaphragm down, drawing air from the
windshield wiper through the inlet port (M) and valve (N).
When the manifold vacuum increases, the diaphragm is
drawn up against the spring and ceases to operate. The
diaphragm operates only when manifold vacuum is insuffi-
cient for wiper operation.
FUEL PUMP TEST:
1. Remove and clean the fuel pump sediment bowl and
screen.
2. Replace the screen if damaged.
NOTE: If the combination fuel and vacuum pump is used,
remove and clean the air filter screen located under the
cover at the top of the pump.
3. Make sure all connections and cover screws are tight after
replacement.
4. Disconnect the fuel line at the carburetor and connect the
fuel pump gauge.
5. Start the engine and run at 1800 RPM. Pressure should
be 3 to 4 pounds with AC combination fuel and vacuum
pump and 3-1/2 to 4-1/2 pounds with Carter M-729SZ.
Stop engine and watch pressure gauge. Pressure should
not fall perceptibly.
6. If pressure falls, leaking pump valves are indicated.
7. If pressure is below specifications, attach vacuum gauge
to inlet port of pump and operate engine. Gauge should
show 6" of mercury or higher for satisfactory operation.
8. If fuel pump pressure is low, but vacuum reading
satisfactory, difficulty is in the gasoline tank or lines
to the pump.
9. If pump pressure and vacuum are both low, pump should
be repaired or replaced.
VACUUM BOOSTER TEST:
To check the action of the vacuum portion of the combi-
nation fuel and vacuum pump, connect a vacuum gauge to
the inlet port and disconnect outlet. Gauge should show
8-1/2" of mercury at 120 RPM and 12" at 1800 RPM. If
vacuum is not within these limits, repair or replace pump.
REMOVAL (8 Cylinder):
1. Remove right front wheel.
2. Remove rear portion of fender dust shield.
3. Disconnect fuel lines from pump.
4. On combination pump, disconnect vacuum lines.
5. Remove cap screws, pump, and gasket pack.
REMOVAL (6 Cylinder):
1. Disconnect fuel lines from pump.
2. On combination pump disconnect vacuum Lines.
3. Remove cap screws, pump, and gasket pack.
Installation:
Install in reverse of removal. Make sure flange gasket (A),
Figure 105, mounting stud insulator bushings (C) and wash-
ers (E) arc placed as indicated in exploded view.
FUEL PUMP OVERHAUL
NOTE: New diaphragms should be dipped in kerosene to
soften them before assembly.
FUEL PUMP DISASSEMBLY (CARTER):
1. Mark pump body and valve housing with a file to insure
correct reassembly.
2. Remove cam lever return spring (F), Figure 105.
4 - 32 FUEL SYSTEM & EXHAUST