FUEL SYSTEM 3-11
Fuel Injection Nozzle
Injection Pressure Check
•
Install the fuel injection nozzle on a nozzle tester.
•
Quickly move the tester lever up and down so that the
injection nozzle sprays two to three times.
○
This step blows off any carbon deposits on the injection
nozzle port.
•
Move the lever very slowly, gradually raising the pressure.
•
Measure the maximum pressure just as the pointer of the
pressure gauge drops s uddenly.
Fuel Injection Nozzle Injection Pressure
Marking of Injection Nozzle:
Red or Green: 13 239 ∼ 14 220 kPa (135 ∼ 145
kgf/cm², 1 920 ∼ 2062psi)
None:
14 465 ∼ 14 955 kPa (147.5 ∼ 152.5
kgf/cm², 2 098 ∼ 2169psi)
If the measured pressure does not comply with the spec-
ification, replace the injection nozzle.
Leakage Check
(When there is a mark (green or red) on the nozzle.)
•
Slowly depress the tester lever, until the pressure reaches
about 11 768 kPa (120 kgf/cm², 1 706 psi.)
(When there is no mark on the nozzle.)
•
Slowly depress the tester lever, until the pressure reaches
about 12 749 kPa (130 kgf/cm², 1 849 psi.)
Checking for “Buzzing” and Spray Pattern
•
Operate the tester lever at a rate of 30 to 60 strokes per
minute in the case of a new nozzle; 15 to 60 strokes per
minute in the case of a used nozzle.
•
Make sure that “buzzing” occurs during these strokes.
NOTE
○
When this “buzzing” occurs, you can feel a pulsation
transmitted to your hand through the nozzle tester han-
dle while the nozzle injection is taking place.
○
When the pressurized fuel from the injection pump is in-
jected, this injection is accompanied by rapid, recurring
pressure variations during the time from the start to the
finish of the injection. These pulsing pressure variations
are felt as “buzzing”.
○
These pulsations of the fuel are affected mainly by the
movement of the nozzle needle and good or bad condi-
tions of the valve seat section.
○
Generally, a nozzle that “buzzes” is good, because a
spray condition where intermittent pulsations are gen-
erated assures good “cut-off” of the fuel supply.
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