Datsun 1980 200SX Service Manual page 128

Condition
Poor
gas
mileage
or
CO reading
too
high
Surge
Backf
uing
ENGINE FUEL
Trouble
Diagnoses
and Corrections
Probable
cause
Improper ignition timing
or
ignition system
Improper
air cleaner f1lter
Improper
fuel pressure
Problem in the
following
circuits
Water
temperature sensor
Air
temperature sensor
Throttle valve switch idle
contact
and
full throttle
contact
Vacuum
switch
Air flow
meter potentiometer
Air
regulator and fuel
pump circuit
Injector
cirelli ts
Malfunctioning air
flow
meter
Intake air
leakage at
the
following points
P C v valve
Dipstick
and
oil ftller
cap
seals
Manifold
gaskets
Air
flow
meter
hoses
etc
Improper fuel
pressure
Improper idle CO adjustment
Problem
in
the
followirig
circuits
Throttle valve
switch
idle
contact
and
full throttle
contact
Vacuum switch
Air
flow
meter
potentiometer
Control
unit
ground circuit
Air
temperature
sensor
Water
temperature
sensor
Altitude
sensor
Air
regulator
and fuel
pump circuit
Ignition
coil
trigger input
circuit
Control
unit
power
input
circuit
Injector
circuit
Intake air
leakage
at the
following points
P
C V valve
V C valve
Dipstick and oil ftller
cap
seals
Manifold
gaskets
Air
flow
meter
hoses
etc
Improper fuel pressure
Improper idle CO
adjustment
Check and corrective action
Check ignition timing
Check ignition system for
hot
spark
Check
air
cleaner f1lter and replace if
necessary
Perfonn fuel
pressure test
Check each circuit
Then proceed
to
Component
checks
Check
air
flow
meter
mechanical
movement
Using
a
fmger
check flap movement
for
smooth
operation
Check for intake air leaks
Perfonn fuel
pressure test
Check idle CO if
necessary
adjust
it
Check each
circuit
Then
proceed
to
Component checks
Check for intake air leaks
Perf
nn
fuel
pressure test
Check idle CO if
necessary
adjust it
EF 41