[jlshack]

Took my SX 18 out on the river on the 10th and all went well with one new odd problem. The engine (3.0L) tachometer was reading about 1000 RPMs high thru out the scale. At idle, instead of reading around 600 to 800 RPMs the tach was reading around 1800 to 2000 RPMs, the engine was idling normally. And at all speed ranges, the tach consistently read about 1000 RPMs higher than it should. Any ideas what could cause this? Thanks.

[mikeyt]

Access the back of the tachometer and you should find a small dial that says 4 - 6 - 8 etc. Spin the pointer a few times and then set it at 4cyl. Sometimes they just go a little funny & lose their brains then need to be reset. IF that doesn't work i believe your Mariah uses Faria gauges which come with a lifetime warranty from the manufacturer.

[jlshack]

Great, I'll give that a try.

[thresher7]

I'm new to this ... excuse me if it's redundant. We've a 1997 Z-276 with a 454. The tach, regardless of engine speed goes bazerk to the point of pegging itself in both directions... Is it safe to assume the same issue, if i remove the access panel, there'lll be a switch i can switch back and forth to see if that's the issue?

[mikeyt]

Yep. It doesn't solve all tach problems but its worth a try.

[thresher7]

Mike, later today I'll take the access panel off and give it a try... thank you... worse comes to worse this winter I'll take the tach out and send it off... thank you

[mikeyt]

Originally Posted by thresher7

Mike, later today I'll take the access panel off and give it a try... thank you... worse comes to worse this winter I'll take the tach out and send it off... thank you

Make sure you check the connections also. There might be a poor one or a wire thats being pinched or near broken somewhere causing the bouncing around.