Hyundai HDF 50-7S, Service Manual

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FUEL SYSTEM
8-8
2.4 Inspecting and adjusting fuel injection
valve opening pressure
CAUTION
Never touch the spray hole during injection
(1)
Mount the nozzle on the nozzle tester.
(2)
Pump the tester handle at a rate of approximately one
cycle per second while observing the pressure at which
injection starts. If the pressure is not in the standard
range, make an adjustment by changing shim.
(3)
To adjust the valve opening pressure, remove the
retaining nut, and change the shim. The thicker the
shim, the more it increases the pressure
(4)
After adjusting the pressure, tighten the retaining nut to
the specified torque.
(5)
Check the injection valve opening pressure once again
to make sure the pressure is within the standard range.
Note: (a) Standard is a value of new parts.
(b) A change in thickness of the shim by 0.1 mm
[0.004 in] results in a change in the fuel injection
pressure by 1.0 MPa {10kgf/cm² } [142 psi].
There are ten different sizes of shims available
1.25 to 1.70 mm [ 0.0492 to 0.0669 in.] to obtain
proper pressure.
Inspecting fuel injection nozzle with nozzle tester
2.5 Inspecting fuel spray pattern of fuel injec-
tion nozzle
(1)
When adjusting the nozzle opening pressure using the
nozzle tester, check for nozzle hole condition, and fuel
spray pattern.
(2)
Checking points of fuel spray are as follows:
· Fuel is injected conically at the specified spray angle.
· Fuel is injected in a spray of fine droplets.
· Fuel is injected without after-dribbling.
(3)
If spray condition is faulty, clean or replace the nozzle
tip.
Inspecting fuel injection nozzle spray condition
Item Nominal Standard
Valve opening
pressure
11.77 MPa
{120 kgf/cm²}
[1707 psi]
11.77 to 12.75 MPa
{120 to 130 kgf/cm²}
[1707 to 1849 psi]
Nozzle tester
Good
Large
spray
angle
After
dribble
Branched
spray
Deflected
spray
Defective spray pattern
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