If one injector is clogged, the others may soon require servicing and it is a good idea to remove all the injectors for servicing or replacement. The principle is simple. By loosening the fuel supply line to the injector, the fuel flow is decreased, imitating a clogged injector and forcing it to misfire. If the engine doesn't misfire when the injector fuel supply line is loosened, that injector can be the problem. The first step is to gain access to the injectors.
Many engines mount the injectors on the exterior of the engine.
Others mount the injectors under the rocker arm cover. If the latter is the case, the covers must be removed to gain access to the injectors. Use a gasket-sealing compound to help prevent oil leaks when replacing the covers. To determine which injector is misfiring, restrict the fuel flow to the injectors one at a time. Each injector has a fuel supply line and a fuel return line.