Chevrolet 10 Series 1970 Service Manual page 378

ENGINE FUEL 6M -14
2. D r ill out spot w elds fastening vacuum m otor r e ­
taining strap to snorkel tube.
3. Rem ove vacuum m otor
linkage rod fro m dam per door.
Replacement
1. D r ill 7/64" hole in snorkel tube at center o f vacuum
m otor retaining strap (fig . 11A).
2. Connect vacuum m otor
Fasten retaining strap to a ir clean er with sheet
m etal screw .
3. R eplace a ir clea n er on engine and check operation
o f vacuum m otor and
TEMPERATURE SENSOR REPLACEMENT
Removal
1. Rem ove a ir clea n er
General D es crip tio n ...............................
Service P roced u res..................................
Fuel Pump Inspection and Test . . . .
Vacuum Section Inspection and Test
Rem oval ..........................................
The fuel pumps used on both the s ix - and eigh t-cylin d er
engines are of the diaphragm type.
phragm fuel pumps a re used, a se rv ic e a b le combination
fuel and vacuum pump and a n o n -serviceab le fuel pump
that because o f design, is s e rv ic e d as an assem bly only.
FUEL PUMP INSPECTION A N D TEST
The fuel pump should be checked to make sure the
mounting bolts and inlet and outlet connections are tight.
A lw ays test pump while it is mounted on the engine and be
sure there is gasoline in the tank.
The line fro m the tank to the pump is the suction side
o f the system and the line fro m the pump to the ca rb u re­
to r is the p ressu re side o f the system . A leak on the
p ressu re side, th e re fo re , would be made apparent by
dripping fuel, but a leak on the suction would not be ap­
parent except fo r its e ffe c t o f reducing volum e of fuel on
the p ressu re side.
1. Tighten any loose line connections and look fo r bends
o r kinks in lin es which would reduce fuel flow .
2. Tighten diaphragm flange screw s.
3. Disconnect fuel pipe at carb u retor.
tributor to c o il p rim a ry w ire so that engine can be
cranked without firin g .
end o f pipe and crank engine- a few revolutions. If
little o r no gasoline flow s fro m open end of pipe then
fuel pipe is clogged o r pump is in op erative. B efore
rem ovin g pump disconnect fuel pipe
outlet pipe and blow through them with an a ir hose to
by liftin g and unhooking
linkage to dam per door.
control dam per assem bly.
fro m engine and disconnect
FUEL PUMPS
Page
6M-14
6M-14
6M-14
6M-15
6M-15
GENERAL DESCRIPTION
Two types of dia­
SERVICE PROCEDURES
Disconnect d is ­
P la c e suitable container at
at gas tank
vacuum hoses at sensor.
2. P ry up tabs o f sensor retaining clip (fig . 12A).
NOTE:
O bserve position of sensor, new sensor
must be in stalled in this same position.
3. Rem ove clip and sen sor fro m a ir clean er.
Replacement
1. Install sensor and gasket assem bly in a ir clean er
in position as noted above.
2. P re s s retaining clip on sensor. Support the sensor
on it sides to preven t damage to the control mech-
amisn in the center.
3. Install a ir clean er on engine and connect vacuum
hoses.
INDEX
In s ta lla tio n ........................................................................................ .. 6M-15
Disassembly ...................................................................................... .. 6M-16
Cleaning and In s p e c tio n .................................................................. .. 6M-16
A s s e m b ly ............................................................................................. 6M-16
The pumps are actuated by an eccen tric located on the
engine camshaft. On in -lin e engines, the eccen tric actu­
ates the pump rock er arm . On V -8 engines, a push rod
(located between the camshaft eccen tric and fuel pump)
actuates the rock er arm .
make sure they a re clea r.
test while cranking engine.
CA U TIO N :
W henever the engine is cranked r e ­
m otely at the sta rter, with a special jum per
cable o r other means, the distribu tor p rim a ry
lead must be disconnected fro m the negative post
on the c o il and the ignition switch must be in the
" O N " position. F a ilu re to do this w ill resu lt in
a damaged
sw itch.
4. If fuel flow s from pump in good volum e from pipe at
carbu retor, check fuel d e liv e ry p ressu re to be c e r ­
tain that pump is operating within sp ecified lim its as
follo w s:
a. Attach a fuel pump p ressu re test gauge to discon­
nected end o f pipe.
b. Run engine at approxim ately 450-1,000 rpm (on
gasoline in carbu retor bowl) and note reading on
p ressu re gauge.
c. If pump is operating p ro p erly the p ressu re w ill be
and within specifications and w ill rem ain constant at
speeds between 450-1,000 rpm.
Reconnect pipes and r e ­
grounding circu it in the ignition
If pressu re is
CHEVROLET TRUCK SERVICE MANUAL
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