Kobelco sk125sr-2Kob/sk135-2 injector problem in Bangladesh

I am from Bangladesh.Here have many kobelco excavators.But kobelco sk125sr-2/sk135-2,sk130-8/sk140-8 which have Mitsubishi D04FR engine. In our country only this engine have injector failure problem.Many of the owner replace the injectors and also install the genuine injector 7 or more times but it doesn't work.Is that any particular problem with Mitsubishi D04FR engine.There are many excavators of Mitsubishi D04FR engine those are in scrap.Can any one give some advice why this injector failure happing.Your advice will help many excavators owner in Bangladesh