fuel injectors with intensified fuel storage and methods of operating an engine therewith . at least one storage cavity is provided in the intensifier type fuel injector , with a check valve between the intensifier and the needle chamber and storage cavity preventing loss of injection pressure while the intensifier plunger cylinder is refilling with fuel . this provides very efficient injector operation , particularly at low engine loads , by eliminating the wasted energy of compressing , venting and recompressing fuel for injection . various injector designs and methods of operating the same in an engine are disclosed .