CE F00VC99002 Bosch Diesel Pump Repair Kit Fuel Injector Repair Kit

Injector FAQ

FAQ: What is Injector Duty Cycle?

ERIKC Answer: To control the amount of fuel that enters the engine the injectors are turned on and off or pulsed very quickly. The amount of time an injector is turned on to deliver fuel is known as the duty cycle. This is measured as a percent, so 50% duty cycle indicates that the injector is held open and held closed for an equal amount of time. When the engine needs more fuel, the time that the injector stays on (its duty cycle) increases so that more fuel can flow into the engine. If an injector stays on all the time, it is said to be static (wide open, or 100% duty cycle).

FAQ: What does the term static means?

ERIKC Answer: If an ERIKC injector stays on all the time, 100% duty cycle, it is said to be static. Injectors should never go static because control of fuel delivery is lost and this can cause catastrophic engine failure. Static injectors, or 100% IDC is normally an indication that the injector is too small for the engine. Injector duty cycle should usually not exceed 80%. Once 80% IDC is reached a bigger injector should be installed.

In some instances low fuel pressure or a failing fuel pump can cause injectors to become static. On the other hand, there are some injectors that will go static if the fuel pressure is too high.

FAQ: What is an Injector’s Static Flow rate?

ERIKC Answer: Manufacturers rate fuel injectors by the maximum amount of fuel that they can flow in a given amount of time at a given pressure. This measurement is known as Static Flow Rate and is normally taken at 100% duty cycle and a fuel pressure of 43.5 PSI.

Example: At 100% duty cycle a 55 pound (lb) injector at 43.5 PSI of fuel pressure will flow 55 pounds per hour.