Panama Dave
Member
I had the same problem with one of my SP275s. There is a tube between the aftercooler and the injector pump (looks like a fuel line but it is for air). It is for sensing turbo boost, and it tells the injector pump to ramp up the fuel. Mine was totally clogged and the engine would not exceed 1800 RPM. I took it off and forced acetone through it with a syringe to clear it. Problem solved. Yours could be partially clogged.