Chevrolet 10 1971 Series, Chassis Service Manual

Page: 245 / 466

ENGINE FUEL 6M-23
SERVICE PROCEDURES
INSPECTION
The fuel pump (fig. 3P) should be checked to make sure
the mounting bolts and inlet and outlet connections are
tight.
TEST
Always test pump while it is mounted on the engine and
be sure there is gasoline in the tank.
The line from the tank to the pump is the suction side
of the system and the line from the pump to the carbure­
tor is the pressure side of the system. A leak on the
pressure side, therefore, would be made apparent by
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.
2. 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. Reconnect pipes and re­
test while cranking engine.
CAUTION:
Whenever the engine is cranked re­
motely at the starter, with a special jumper
cable or other means the distributor primary
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.
3. 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 dis­
connect end of 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 significantly at dif­
ferent speeds, the pump should be replaced.
REM OVAL
1. Disconnect fuel inlet and outlet pipes at fuel pump.
2. Remove fuel pump mounting bolts and remove pump
and gasket.
3. On V8 engines if push rod is to be removed, remove
pipe plug and push rod (396, 400, 427 and 454 cu. in.
engines), and fuel pump adapter and gasket and push
rod 302, 307, 350 and 400 cu. in. engines).
INSTALLATION
1. On V8 engines, if fuel pump push rod has been re­
moved, install push rod and pipe fitting or fuel pump
adapter using 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 V8 engines, a pair of mechanical
fingers or heavy grease may be used to hold
fuel pump push rod up while installing fuel pump
(fig. 4P).
3. Connect fuel pipes to pump.
4. Start engine and check for leaks.
OUTLET
INLET
Fig. 3P— Fuel Pump (N o n -Se rvic e a b le )
Fig. 4P— Installing V - 8 Engine Fuel Pump
10-30 CHEVROLET TRUCK SERVICE MANUAL