[jmo]

Tach changes 500-800rpms throughout rpm range without any increase in throttle.

Any thoughts...Justin

[WetWilly]

Hi Justin,

Sounds like a small problem with corrosion, try to gain access to the back side of the tach, there, you should find a small dial for selecting the number of cylinders your motor has. Mark it's current position with a permanent marker then rotate it back and forth several times, the selector contacts are known for becoming corroded and causing all sorts of miss reading. Don't forget to check the wiring connections to the tach as well.

Now if it still looks like the tach is at fault, and your tach is made by Faria, contact them (click here) as they have a lifetime warranty repair service and I believe the fee is around $30 to $50 for the tach, that's cheaper than a new one...

Good luck,
WetWilly

[jmo]

Thanks...I'll check it out next time @the lake.