03 gtx new owner

[03gtx4tec]

I acquired a 2003 gtx sc, first time owner of a ski. With a litte work got it running. it needs a jet pump and impeller I'm sure. Anyway was running good and one day wouldn't crank. I'm think two things fuel pump or CPS. the guages do not work so I do not know how many hours it has. When should the engine be gone through and what do they do when you have this done? What should I look for to check engine compression etc... Any advice thanks