RG1
Platinum Member
I'm not familiar with the 4115, but when you said you changed the fuel filter, are you sure there is only one? It sounds like you changed the filter in the sediment bowl/water separator. I know with my 2520 there is also a spin on filter on the side of the engine just before the injection pump.
There's just the one in the line at the sediment bowl on the 4115.