Fuel Injection System - Diesel: Operation: Injectors
The injection spray nozzles spray fuel into a combustion prechamber as each compression stroke occurs. Nozzles can be disassembled, cleaned, and adjusted to correct improper spray patterns.
The injector receives a high pressure pulse of fuel, which forces the needle valve to open, allowing fuel to pass into the prechamber. Injector opening pressure can be adjusted with shims on top of the needle valve return spring. See Fig 1 .