Bouncing Tach problems

[Waterdog ls]

Have a 1999 Moomba outback LS with a tachometer that is bouncing. I get up to 38 miles an hour and the tachometer starts to bounce around 4200-4300 RPMs. The Bouncing as a range from 4200 to 4700 RPMs. My boat used to do 42 43 mph in no longer does that I feel because of the bouncing tachometer is causing the rev limiter to engage. When tachometer starts to bounce I still have almost 2 inches of throttle left but get no response.
Any ideas would be greatly appreciated thanks in advance

[mmandley]

You need a new Tach.
Not much you can do to stop the bouncing.

As long as the engine isn't surging the tach should stay steady.


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[Waterdog ls]

Pulled tach out didn't fix speed problem.
Carb run great up to 38 then dogs
Anyone help?

[zabooda]

My tach has been doing that for years. I tap the glass until I get the rpm I expect. For real. It is a tach and hour meter and that is it. I suspect your throttle linkage.

[zuziak]

Check for a new Tach.

[TrueKaotik]

Your tach doesn't stop the motor from reving up it just reads it.so this won't be your issue. It sounds like a fuel air spark issue possibly, has it thrown any codes? Have you replaced the distributor cap, fuel filter and air filter recently?

[Waterdog ls]

Just put a Acme 475 prop on my boat and got back to 44 mph.
Also found out after taking the prop I had on my boat back to the shop that worked on the prop that they never worked on that prop.
Meaning the place that did my carb work switched my prop. causing the tack and speed issue.
The place that does props stamps the props with a work number. I always said that they switch my prop but could never prove it till now.
Really if you hit something with a boat you are working on own up to it and fix the problem.
They have lost my Business forever not to mention my friends Business.