TM 9-4910-677-14 & P
VACUUM BOOSTER PUMP
With the ignition switch in the
Disconnect both sides of the pump
and connect the vacuum gauge on the
position, the throttle closed
wiper side. The reading should be
tightly, use the starting motor to
steady between 7 and 12 inches. A
turn the motor and note the indicator
ruptured diaphragm may cause high
reading. It should read between 8
and 14 inches. Failure to do so in-
oil consumption, poor engine idle or
fouling of spark plugs on one side of
dicates an open intake due to the
b u t t e r f l y not closing properly, a
leaky intake manifold gasket or
burnt heat risers.
Accelerate the motor quickly
several times in rapid succession.
With a clear muffler the indicator
Open throttle, close the choke,
needle has a quick return to nor-
and step on the starter. The gauge
mal each time while with a clogged
should read, at least, 2 inches, or
muffler, the indicator needle will
as high as 6 inches depending on the
have a tendency to be sluggish and,
type of choke. If you cannot get the
in severe cases, will not raise be-
desired reading, the choke valve is
yond 8 inches and will show excess-
not closing properly which usually
causes hard starting.
If these readings are not obtained,
To make a fuel pump pressure
pump repairs are necessary.
test, remove the gas line from the
FUEL FLOW TEST
pump to the carburetor at the fuel
pump. Remove the 1/8" pipe fitting
To determine if gas line or gas
from the pump. Insert the 1/8" pipe
tank is clogged, connect T fitting
fitting supplied with the analyzer and
between fuel pump and line to gas
fasten the hose from the pressure
tank. Attach hose from gauge to re-
gauge to it. Make sure the fittings
maining nipple of tee. Operate the
are all air tight. Operate the motor
motor at 10 to 15 miles per hour. If
at 10 to 15 miles per hour.
gas line and tank cap are clear, the
reading on the gauge should be not
gauge reading will fluctuate between
less than 2, and not more than 3-1/2
0 and 1 inch of vacuum, and steady
pounds; and not less than 1/2 pound
reading above one inch of vacuum
on wide open throttle. If these read-
indicating partially or wholly ob-
ings are not obtained, pump repairs
structed gas line or tank cap.
are necessary. On late model Olds-
MUFFLER BACK PRESSURE TEST
mobile - 6 cylinder - specifications
call for 4-1/2 pounds maximum.
To make a muffler back pressure
the 8 cylinder, 3-1/4 pounds maximum.
test, it is necessary to drill and tap
for 1/8" pipe fitting in the exhaust
To make a fuel pump vacuum test,
flange as possible. Insert the 1/8"
remove the gas line from the pump
pipe fitting and attach the hose lead-
and, using the proper adapter sup-
ing to the pressure gauge. Start the
motor. If a pressure of 3 pounds or
plied, attach the hose of the vacuum
gauge. Operate the motor to 10 to
replaced. Motor speed to be approx-
15 miles per hour. The reading on
the gauge should be 8 or more inches.
imately 50 miles per hour.
ALTITUDE COMPENSATOR FOR VACUUM GAUGE
Reading - Normal Motor
S e a Level