The only gauges that work on my boat are the trim, the oil pressure and sometimes the tach. I was thinking about using diamond plate for the dash and just getting some new gauges and wires. Any help on figuring out how to make the other gauges work. 2 gas gauges, and a speedo.

What model of boat/motor/year? Gas gauges are traditionally unreliable as the boat is never level but the speedometer can be fixed or replaced if necessary. Best thing to do is get a service manual for your boat..Seloc is the best you can get them off Ebay for little of nothing...the manual will walk you through troubleshooting all your gauges..I just had to do this myslef on my Merc.

"Sometimes the tach"? Bad tach can be symptomatic of failing rectifier...how's your battery charging voltage?

Gas gauges:
Normally three wires, purple (usually) for power from the accessory terminal of the keyswitch, one from the sender, and one to a panel light switch (or ground).

You should have approx 12 volts at the purple wire (at least more than ten) - if not, troubleshoot the purple wire and keyswitch.

Inspect the connections on the gauge for corrosion, split or missing insulation, connections should be good & tight.

With the key on, ground the terminal leading to the light switch and disconnect the sender wire - the gauge should peg Empty; it should peg Full with the sender terminal grounded. (Yours might be the other way round...Full then Empty, doesn't matter long as it's opposite). If it doesn't, replace the gauge. If it does, you either have a bad sender or a wiring fault upstream of the gauge. Or maybe a broke or stuck float.

Sorry, can't help with the speedometer.

Good luck...

I have a manual, i think its a seloc. The boat is a 89' 17 foot kingfisher, and the motor is a 91' Mariner 150. I'm just out of town all week and never get to work on my boat as I'd rather go fishing with a few bad gauages than wory about fix them on the weekend. Thanks for the advise on the gauages, I give it a shot this weekend.

I've got the Seloc manual for your boat if you don't have it...I have a 1990 Mariner 150....I work on mine extensively so if you ever need help with anything let me know.

Alright, I have one. I've done alittle work on it but its had its time in the shop. I just got a tracker trailer for it and have to figure how to make it all line up. so might just have to hold up on the gauages for a week or so. Kind of dred working on the boat, rather go fishing.

You probably have connection problems on power or ground, except for speedo, just takes water pressure (stopped up line). Look for bad connections at fuse buss probably under console. Check with test light. Good Luck