Chevrolet 30 Series 1967 Service Manual page 338

ENGINE FUEL 6M-14
dripping fuel, but a leak on the suction would not be ap­
parent except for its effect of reducing volume of fuel on
the pressure side.
1. Tighten any loose line connections and look for bends
or kinks in lines which would reduce fuel flow.
2. Tighten diaphragm flange screws.
3. Disconnect fuel pipe at carburetor. Disconnect dis­
tributor to coil primary wire so that engine can be
cranked without firing. Place suitable container at
end of pipe and crank engine a few revolutions. If
little or no gasoline flows from open end of pipe then
fuel pipe is clogged or pump is inoperative. Before
removing pump disconnect fuel pipe at gas tank and
outlet pipe and blow through them with an air hose to
make sure they are clear.
test while cranking engine.
CAUTION: Whenever the engine is cranked re­
motely at the starter, with a special jumper
cable or other means, the primary distributor
lead must be disconnected from the negative post
on the coil and the ignition switch must be in the
"ON" position. Failure to do this will result in a
damaged grounding circuit in the ignition switch.
4. If fuel flows from pump in good volume from pipe at
carburetor, check fuel delivery pressure to be cer­
tain that pump is operating within specified limits as
follows:
a. Attach a fuel pump pressure test gauge to discon­
nected end of pump to carburetor pipe.
b. Run engine at approximately 450-1,000 rpm (on
gasoline in carburetor bowl) and note reading on
pressure gauge.
c. If pump is operating properly the pressure will be
within specifications and will remain constant at
speeds between 450-1,000 rpm. If pressure is
too low, too high, or varies materially at different
speeds, the pump should be replaced.
VACUUM SECTION INSPECTION AND TEST
NOTE: These procedures can be used only on
the combination pump.
Test the vacuum section of the pump by fully opening
the windshield wiper valve and observe wiper blade speed
while alternately idling and accelerating the engine.
Wiper blade speed should be fairly constant regardless of
engine speed or throttle opening.
NOTE: A dry windshield
speed. If windshield wiper does not operate
properly, make the following inspection and test.
1. Make certain that hoses are properly connected at
pump, wiper motor and control at instrument panel
and double check valve, and that connections are air
tight. Replace cracked or deteriorated hose.
2. If windshield wiper does not operate properly after
all points of leakage have been corrected, detach both
pipes at vacuum pump and join them with a piece of
tubing. Slowly operate engine from idle to about
rpm; the wiper should run at full speed operat­
1 0 0 0
ing on engine vacuum only. If it does not, it can be
assumed that the wiper motor or tubing is defective.
The pump vacuum section is inoperative if the wind­
shield wiper operated properly on engine vacuum, but
not on pump vacuum.
Reconnect pipes and re­
will slow wiper
3. A further test of vacuum pump may be made by at­
taching a vacuum gauge to the inlet port (port con­
nected to wiper motor) with outlet pipe disconnected.
CAUTION: Always make this test of vacuum
pump with outlet open.
With engine operating at 750 rpm the gauge should
4.
show 10 to 12 inches of vacuum.
of vacuum indicates an inoperative vacuum pump.
Removal
1. Disconnect fuel inlet and outlet pipes at fuel pump.
On "P " Models, disconnect vacuum lines at pump.
2. Remove fuel pump mounting bolts and remove pump
and gasket.
3. On V engines: if push rod is to be removed, re­
- 8
move fuel pump adapter and gasket then remove push
rod (283 and 327 engines).
If a new fuel pump is to be installed, transfer fittings.
4.
NOTE: After removal of pump from engine and
before disassembly is started, plug all openings
and thoroughly wash exterior of pump with
cleaning solvent to remove all dirt and grease.
Installation
1. On V engines: if removed, install fuel pump push
- 8
rod and fuel pump adapter. Use gasket sealer on
gasket or pipe fitting.
2. Install fuel pump using a new gasket and tighten se­
curely. Use sealer on fuel pump mounting bolt
threads.
NOTE:
On V engines, a pair of mechanical
- 8
fingers may be used to hold fuel pump push rod
up while installing fuel pump (fig. 3P).
3. Connect fuel pipes to pump. On "P " Models connect
vacuum lines to pump.
Start engine and check for leaks.
4.
FUEL AND VACUUM PUMP UNIT
Disassembly
1. Scratch locating marks on fuel cover and pump body
so that inlets and outlets will be properly located
when pump is reassembled.
2. Remove bolt and lockwasher holding down pulsator
cover on fuel side of pump. Remove pulsator cover
and pulsator diaphragm.
3. Remove screws and washers holding fuel cover to
pump body and remove cover.
Place pump rocker arm in soft jawed vise so that
4.
vacuum side is up and remove all vacuum cover
screws except any two that
opposite.
5. P ress down firmly on vacuum cover to hold heavy
vacuum diaphragm spring compressed and remove
remaining two screws. Release vacuum cover slowly
and remove cover assembly, diaphragm spring and
spring retainer.
NOTE:
If desired, two 10-32NF 1 -1 /2 " screws
may be screwed diametrically opposite into cover
to aid in relieving diaphragm spring pressure
when removing cover.
. Lift vacuum diaphragm and remove vacuum valve
6
Less than 10 inches
are diametrically
CHEVROLET TRUCK SERVICE M ANUAL