Testing fuel pressure 1
a Testing tools for fuel pressure
k Stop the machine on a level ground and
lower the work equipment to the ground.
a Test only the fuel pressure in the low-pressure
circuit from the priming pump through the fuel
main filter to the supply pump and the return
circuit from the supply pump/common rail/
injector to fuel tank.
k Since the pressure in the high-pressure cir-
cuit from the supply pump through the
common rail to the injector is very high, it
cannot be tested.
1. Testing pressure in fuel low-pressure cir-
cuit
1) Open the engine hood and remove fuel
pressure pickup plug (1) from the fuel
main filter.
2) Install adapter F2 and nipple [1] of the
hydraulic tester F1 and connect them to
gauge of boost gauge kit F3.
3) Run the engine at high idle and test the
pressure in the fuel low-pressure circuit.
a If the pressure in the fuel low-pres-
sure circuit is in the following range, it
is normal.
Reference: Negative pressure is indi-
cated.
4) After finishing test, remove the testing
tools and return the removed parts.
3 Fuel pressure pickup plug:
7.8  9.8 Nm {0.8  1.0 kgm}
Symbol Part No. Part name
F
1
799-101-5002 Hydraulic tester
790-261-1204 Digital hydraulic tester
2
795-471-1450 Adapter (8 x 1.25 mm)
07005-00812 O-ring
3 799-201-2202 Boost gauge kit
Engine speed Fuel pressure
At high idle
-49  0 kPa
{-0.5  0 kg/cm
2
}
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