If an injection nozzle is not properly delivering fuel into the pre-combustion chamber of a cylinder, driveability could be greatly effected, or a diagnostic trouble code (DTC) could be set. If other diagnosis indicates, or if the injection nozzles are suspected of not properly delivering fuel, they should be tested. Typically, a nozzle failure can be detected by using the injector balance test.

Nozzle testing is comprised of the following checks:

An injector balance test is performed with the scan tool. This test will properly identify a stuck closed or noisy injector nozzle. Typically, a nozzle failure will fall into this criteria.

1. Install a scan tool.
2. Start and idle the engine.
3. Perform the injector balance test on each cylinder.

If a suspect nozzle has been located, the nozzle can be swapped with the adjacent cylinder and balance test can be repeated as a check to positively identify a malfunctioning nozzle.

4. Locate and replace the malfunctioning nozzle and glow plug.

Caution: Do not place your hands or arms near the tip of the nozzle when testing the nozzles. The high pressure atomized fuel spray from a nozzle has sufficient penetrating power to puncture flesh and destroy tissue. This may result in blood poisoning. Always enclose the nozzle tip in a receptacle, preferably transparent, in order to contain the spray.

Important: Injector Nozzle Opening Pressure and Leakage tests should only be performed on vehicles with high mileage, engines that have been over heated or on vehicles that pull heavy loads. False or inaccurate readings can occur if the following tests are not performed to the above criteria.

Important: Each test should be considered independent of the others (for example, when checking opening pressure, do not check for leakage). If all of the following tests are satisfied, the nozzle assembly can be reused. If any one of the tests is not satisfied, the complete nozzle assembly must be replaced. When performing the injection nozzle tests, refer to the instructions provided with the J 29075-B Nozzle Tester.

1. Open the shut-off valve at the pressure gage one-quarter turn.
2. Depress the tester lever slowly. Note at what pressure the needle of the pressure gage stopped. The maximum observed pressure is the opening pressure. Some nozzles may pop while other nozzles may drip down (this is not leakage).
3. The opening pressure should not fall below the lower limit of 105 bar (1,500 psi) for naturally aspirated engines and 117 bar (1,700 psi) for turbo-charged engines for used nozzles.
4. Replace nozzles which fall below the lower limit.

Caution: Do not place your hands or arms near the tip of the nozzle when testing the nozzles. The high pressure atomized fuel spray from a nozzle has sufficient penetrating power to puncture flesh and destroy tissue. This may result in blood poisoning. Always enclose the nozzle tip in a receptacle, preferably transparent, in order to contain the spray.

Important:  Injector Nozzle Opening Pressure and Leakage tests should only be performed on nozzles with high mileage, engines that have been over heated, or on vehicles that pull heavy loads. False or inaccurate readings can occur if the following test are not performed to the above criteria.

1. Open the shut-off valve at the pressure gage (1 turn).
2. Blow dry the nozzle tip.
3. Depress the lever of the manual test stand slowly until the gage reads a pressure of 95 bar (1400 psi). Observe the nozzle tip. A drop may form on the end of the nozzle but should not drop off within a period of 10 seconds.
4. Replace the nozzle assembly if a drop falls during the 10 seconds.