How can a mechanic determine if an injector is working correctly?

A mechanic can determine if an injector is working correctly by performing a balance test or flow test. This process involves measuring the amount of fuel delivered by each injector over a certain period of time while the engine is running. By comparing the fuel flow rates of each injector, the mechanic can identify any discrepancies that may indicate a malfunctioning injector.

If one injector is delivering significantly more or less fuel than the others, it could signal issues such as clogging, leaking, or internal failure. This method provides a quantitative measure of injector performance, which is more reliable than subjective assessments like visual inspection or indirect indicators such as fuel levels or exhaust gas composition.

While visual inspections can reveal obvious physical issues, they do not provide a complete picture of an injector's operational capacity. Similarly, checking the fuel level alone does not assess the performance of the injectors directly, nor does measuring exhaust gases give specific insights into each injector's functionality. The balance or flow test offers a definitive diagnostic approach to evaluate injector operation.