POWER TRAIN

TM 10-3930-623-12

6-61. INSTALLATION.

6-65.1. FUEL PUMP TEST.

1. Static pressure test.

1. Carefully place radiator in position, and install

a. Disconnect fuel pump-to-carburetor line at

mounting screws and washers.

carburetor.

2. Reconnect

engine-to-radiator

hoses,

b. Install adapter and T-fitting in opening and

transmission to-radiator hoses, close engine and radiator

attach a pressure gage rubber tubing to the line.

drain cocks, and replace coolant.

c. Run engine at 500 revolutions per minute

6-62. POWER TRAIN.

or until fuel remaining in carburetor is used.

6-63. Removal and installation of the power train, which

d. The reading on the gage is the static

includes the power axle, transmission and the engine, is

pressure of the fuel pump and should be 3 /2 to 5

ordinarily not within the capacity of equipment available

pounds per square inch. Since inaccurate readings may

to the using facility. Should a component of the power

result if a longer hose is used, the length of hose on the

train have to be removed, refer the truck to a suitably

pressure gage should not exceed 6 inches.

equipped overhaul facility.

e. Replace pump if static pressure test

6-64. FUEL

FILTER,

FUEL

PUMP

AND

shows an under pressure or an overpressure reading.

CARBURETOR.

2. Capacity test. The capacity test is designed to

6-45. REMOVAL. Before starting removal of any fuel

measure amount of fuel that the pump will deliver in

system units, shut off the fuel supply by dosing the valve

excess of fuel needed to operate engine at idling speed.

at the point that the fuel line is connected to the top of

the fuel tank,

a. Disconnect fuel pump-to-carburetor line at

carburetor and attach T-fitting in carburetor inlet

opening.

1. Disconnect the fuel line at the filter inlet, then

unscrew the filter (see figure 1-2) from the fitting

b. Attach fuel line to T-fitting.

connecting it to the fuel pump.

2. Remove and save all reusable fittings as work

c. Start engine and count time necessary to

proceeds. Disconnect the pump-to-carburetor fuel line,

fill 1-pint measure with fuel from remaining opening in T-

remove the two nuts and washers which attach the

fitting. Adequate fuel delivery is available when 1 quart

pump to the engine crankcase and take off the pump.

flows in 1 minute or less at 500 revolutions per minute.

Discard the pump mounting gasket. Drain remaining

gas from pump in a safe place.

3. Bench test.

3. Remove spring clips at carburetor end of throttle

and governor linkage, and disconnect linkage at

a. Clamp fuel pump in vise. If vise jaws have

serration's, use brass shims to protect gasket surface of

carburetor.

Loosen hose clamp at carburetor and

pump flange.

remove air intake hose. Loosen, but do not remove

choke cable housing screw, and choke wire screw at

b. Connect mercury manometer or suitable

choke valve lever arm. Set choke cable aside.

vacuum gage to intake side of pump.

4. Remove the two nuts and washers holding the

c. Actuate cam lever a full stroke at 60

carburetor to the intake manifold, remove carburetor and

strokes per minute. The pump should pull at least 10

drain fuel from the carburetor. Manifold-to-carburetor

inches of mercury. If it does not, replace pump.

gasket may be saved for reuse if it is in good condition.

6-8.1