Datsun 620 Series 1977 Service Manual page 132

Engine
Fuel
toms and
causes
of carburetor troubles
and
remedies for
them
are
listed to
facilitate
quick repairs
There
are
various
causes
of
engine
malfunctions
It sometimes
happens
that
a
carburetor which has
no
fault
TROUBLE
DIAGNOSES AND
CORRECTIONS
In the
following
table the
syml
Condition
Probable
cause
Overflow Dirt accumulated
on
needle valve
Fuel pump pressure
too
high
Needle valve
improperly
seated
Excessive fuel
consumption
Fuel
overflow
Slow jet
too
large
on
each
main
jet
Main
air
bleed
clogged
Choke valve does
not open fully
Outlet valve
seat
of accelerator
pump
improper
Linked
opening
of
secondary
throttle valve
opens too early
Power
shortage
Main jets clogged
Every throttle valve does
not
open
fully
Idling adjustment
incorrect
FIICI
tr clogged
Vacuum jet
clogged
Air c1eane
clogged
Diaphragm damaged
Power valve operating improperly
Altitude
compensator setting
incorrect Cali
fornia models
Improper idling
Slow
jet clogged
Every
throttle valve does
not
close
Secondary
throttle valve operating
im
properly
Throttle valve shafts
worn
Packing
between manifold
carburetor
fauJiy
Manifold carburetor
tightening
improper
Fuel overflow
B C D D
adjustment incorrect
Vacuum control solenoid
damaged
Stuck
anti
stall
dash
pot
EF
36
appears
to
have
some
problems
when
actually
the electric system is
at
fault
Therefore
whenever the
engine
is mal
functioning
the electrical
system
should be checked rust before adjust
ing
carburetor
Corrective
action
Clean needle valve
Repair
pump
Re place
See
condition overflow
Replace
Clean
Adjust
Lap
Adjust
Clean
Adjust
AdjusL
pa ir
Clean
Clean
Replace
Adjust
Correct H L lever
position
Clean
Adjust
Overhaul
and clean
Replace
Replace
packing
Correct tightening
See
l
ondition
ov
rl1ow
Adjust
Replace
Replace