What happens when the opening pressure of a diesel fuel injector exceeds the manufacturer's specification?

When the opening pressure of a diesel fuel injector exceeds the manufacturer's specification, the injector may not operate optimally, leading to a decrease in the effective quantity of fuel being injected into the combustion chamber. This can occur because the fuel may atomize improperly under excessively high pressure, causing incomplete combustion and reducing overall engine performance.

Higher opening pressures can result in the injector opening too late or closing too early, which may hinder the amount of fuel delivered during the injection event. This improper injection quantity can also impact engine efficiency and emissions, as less fuel can mean insufficient combustion for optimal power output.

In contrast, the other options suggest an either guaranteed increase in injected fuel quantity or changes in timing or duration that are not directly established outcomes of exceeding the opening pressure specification. Thus, maintaining the injector within the specified pressure range is critical for achieving the desired fuel delivery characteristics and overall engine performance.