This is the part 2 of fuel injector overhaul series, overhauling and testing of fuel injector.

Take out the injector and place it on the vise.

Open the cap nut.

Open the locking nut.

Loosen the adjusting screw.

Now loosen the retaining nut.

Be careful that if the retaining nut is opened without releasing the pressure on adjusting screw, the nozzle may get damaged.

Take out the retaining nut together with the atomizing nozzle.

The atomizing needle valve may come loose.

Be careful not to let it fall down.

Push out the nozzle from the retaining nut.

Take out the double pins, adjusting screw, spring, spring retainer, pushrod and the o-rings.

Thoroughly clean all the parts.

The nozzle and needle valve comes as a pair.

Never interchange them with another one.

Always recommended to use a new nozzle rather than using a corrected bad nozzle by lapping.

The nozzle should be changed with a new one after its service life.

In case reusing the nozzle, do lapping with a thin lapping paste.

Never do lapping of the nozzle needle valve.

Attempt to lap the nozzle needle valve will deteriorate the condition of sealing faces.

At most care should be taken not to damage the sealing faces.

Check the length of the spring with a new one.

If it is less than the new one, discard it.

Insert and pull out the needle valve to check its movement.

Is the movement smooth?

Is the movement not too free?

If it is too free, discard the nozzle.

The oil passage is shown in the red line.

When the fuel pump pumps the fuel oil at high pressure to the injector, it pushes the needle valve of the atomizing nozzle backwards against the spring force and sprays the fuel oil.

Oil goes inside through this hole.

It's the sealing face of the needle valve.

Now we will assemble back the fuel injector.

Install the pushrod, spring and the spring retainer.

Install the adjusting screw.

After that, install the dowel pin, then the nozzle and the nozzle retaining nut.

Tighten the nozzle retaining nut to the torque specified in the manual.

If the retaining nut is tightened with too much torque, the needle valve of the nozzle may stuck.

So tighten it with care.

Checking of the valve opening pressure.

The oil used for testing should be clean diesel oil only.

Keep the valve on the test bench.

Connect the test pump and fuel injector by means of high pressure hose.

Avoid approaching your hand near to the nozzle tip while test is performing.

If hit by jet, it will cause injury.

Quickly move the lever of test pump to bleed air until the pointer of the pressure gauge begins to move and air is ejected.

Slowly move the lever about once a second and read the pressure at which injection start.

Adjustment of injector opening pressure.

Turning in the adjusting screw is increasing the opening pressure and turning out the adjusting screw is decreasing the opening pressure.

Slowly increase the pressure.

Now the opening pressure has reached to 420 bar, which is the pressure specified in the manual.

Install and tighten the locking nut paying attention that the adjusting screw should not move.

Tighten the cap nut.

Again test the opening pressure to confirm that the set pressure has not changed.

Now we will do the checking of injection characteristics.

That include checking of clogging of the nozzle, faulty movement of the needle valve and drips of fuel oil.

Look to confirm that the injection is uniform and fine.

Listen for sound of injection to confirm whether it is sharp.

Check for any sudden fall in pressure after pumping has been stopped.

Doing a injection test on a white paper to see that it is normal and uniform.

Confirm there is no leak on the injector nozzle tip.

Now slowly release the pressure from the high pressure hose.

Take out the injector from the test bed and keep on the stand.

Wrap the injector in such a way to protect the nozzle and fuel inlet area from dust and dirt.