How to Test Injectors on 6.6L Duramax

The 6.6L Duramax is a highly reliable diesel engine overall, but its fuel injectors require periodic maintenance and sometimes are prone to failure. If your vehicle relies on this engine, here’s how to test injectors on the 6.6L Duramax.

Balance Testing Provides a Basic Chack

Balance testing is a common way to check fuel injectors, and it can serve as a helpful basic check. The testing is only a basic check, however.

A balance test analyzes fuel injector balance measurements that are taken by the engine control module (ECM). While these measurements are useful, there are three ways that they fall short of providing all the information that a diesel technician or a driver might want:

The ECM only records balance measurements when the engine is idling, leaving data for actual driving conditions unavailable.

The ECM measures the fuel rate from the fuel pump to determine balance, and several other issues can affect this measurement. Cylinder compression, fuel rail pressure and fuel pressure regulator issues can all lead to inaccurate balance data.

Balance data doesn’t reveal return flow, solenoid response time or external leakage issues.

Thus, balance testing has its place in 6.6L Duramax fuel injector diagnostics. The test may point to likely issues or non-issues, but it shouldn’t be considered definitive or conclusive. The test should be taken for what it is: a helpful basic check for fuel injectors.

Diesel Technicians Know How To Test Injectors on 6.6L Duramax Engines Thoroughly

The only way to comprehensively and definitively test 6.6L Duramax fuel injectors is to have a technician at a diesel service center test them.

In order to be comprehensively checked, fuel injectors must be removed from a vehicle and tested at the full range of operating conditions. They must be checked at idle, low and full-load pressures (which can reach 29,000 psi).

A diesel service center will have the equipment and expertise necessary to perform this level of testing. The testing will check injector delivery, response time, return flow, leakage and spray for a truly thorough assessment of how an injector is working in all operating conditions.