Abstract: Disclosed is an apparatus for cleaning fuel injectors used for injecting fuel into an internal combustion engine. The apparatus comprises a first means for connecting a source of cleaning fluid to a first end of said apparatus, the cleaning fluid introduced to the apparatus being pressurized; a second means for connecting a second end of the apparatus to a fuel delivery line used for delivering fuel to the injectors, the second means permitting delivery of cleaning fluid into fuel in the fuel line, the first means and second means connected by a cleaning fluid delivery conduit.