Yanmar 6CXM-GTE2 Service Manual download pdf (Page 110)

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3.11.20 Troubleshooting of fuel oil system

(1) Before removing fuel injection pump

It is necessary to find out the cause of the trouble before

replacing the defective parts.

The cause of the trouble may not necessarily be in the

pump itself, but may be in the engine or the fuel oil sys-

tem.

If the pump is removed prematurely, the cause of the

trouble may never be known.

Before removing the pump from the engine, at least go

through the basic check points given here.

Basic check points

࡮ Check for breaks or oil leaks through out the fuel system,

from the fuel tank to the nozzle.

࡮ Check the injection timings for all cylinders.

Are they correctly adjusted?

Are they too early or too late?

࡮ Check the nozzle spray.

࡮ Check the fuel delivery. Is it in good condition?

Loosen the fuel pipe connection at the injection pump

inlet, and test the operation of the fuel feed pump.

(2) Major faults and troubleshooting

Fault Cause Remedy

1. Engine won't

start.

Fuel is not delivered

from injection

pump.

(1) No fuel in the fuel tank.

(2) Fuel tank cock is closed.

(3) Fuel pipe system is clogged.

(4) Fuel filter element is clogged.

(5) Air is sucked into the fuel due to defective connections in the pip-

ing from the fuel tank to fuel feed pump.

(6) Defective valve contact of feed pump

(7) Piston spring of feed pump is broken.

(8) Inter spindle or tappet of feed pump is stuck.

Supply

Open

Clean

Replace element

Repair

Repair or replace

Replace

Repair or replace

Nozzle does not

work.

(1) Nozzle valve does not open or close normally.

(2) Nozzle seat is defective.

(3) Case nut is loose.

(4) Injection start pressure of nozzle is too low.

(5) Nozzle spring is broken.

(6) Fuel filter is clogged.

(7) Excessive oil leaks from nozzle sliding area.

Repair or replace

Inspect and tighten

Adjust

Replace

Replace element

Replace nozzle assembly

Injection timing is

defective.

(1) Injection timing is retarded due to failure of the coupling.

(2) Camshaft is excessively worn.

(3) Roller guide is excessively worn.

(4) Plunger is excessively worn.

Adjust

Replace camshaft

Adjust or replace

Replace plunger assembly

2. Engine starts, but immediately

stops.

(1) Fuel pipe is clogged.

(2) Fuel filter is clogged.

(3) Improper air tightness of the fuel pipe connection or pipe is broken

and air is being sucked in.

(4) Insufficient fuel delivery from feed pump

Clean

Disassemble and clean, or

replace element

Replace packing, replace

pipe

Repair or replace

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Yanmar 6CXM-GTE2 Service Manual Page 110

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