Electrical Gremlin!
 

Ive got some sort of issue, i think it is a ground but i wanted some advice before i go tearing things up. My RPM gauges are a little loopy, they work fin up till about 4000 rpms, then they dance and bounce all over.

they also dance and bounce when i hit the trim switch or tabs,

then they will shut righ off if i flip on the "panel" switch on the dash that lighs up the gauges.

this is on a 30' 2000 cigarette

where should i start, the grounds on the bateries are in pretty good shape

Sounds like you have a voltage level problem could be either plus or minus. Start with hooking up a voltmeter to the power bus behind the dash panel. Run the motors play with tabs & panel lights see what the supply voltage is. If its low your problem is gonna be from the power bus back. If the voltage is good the your problem is somewhere between the instrument panel and the power bus. If the problem is there try running jumpers both plus and minus between the power bus and meters and see if it goes away.:p

Boomer,
I have the same problem. Here's what I've done so far.
- I ran ground wire directly from battery to tach
- I ran power wire directly from battery to tach
- I ran signal wire from MSD box to tach
- I grounded the distributor to the block with a wire
The wires were done thinking I had a problem in the wire harness. None of this has helped at all!
The MSD box checks out OK. I am going to try a different tach next.
This is very frustrating as I am trying to dial in a new prop!
Dave

nobody?