Evinrude electrical problem

[JAV370A]

I have a 2001 150 hp ficth and my problem is with the gauges . when idiling and mid range tach is fine but when get into higher rpms tach goes way over to 7000 and when i hit the trim button the tach drops way down . I have gone over and replaced all grounding to the console and guages . and never worked . Also when idiling my gas gauge does not keep a steady signal it bounces around but has a beat to it .almost like a pulse about every 2 secs , any input would be appreciated .Motor runs great without a miss .
Brian

[ChampioNman]

Wing nuts on the battery??? If so change out to Nylon insert hex nuts and lock washers, sounds like a bad ground.

[RUSTY63]

Welcome to the BBC.

The tach sounds like it needs to be replaced and the fuel sender may be the problem with the fuel guage.