Tachometer needle bouncing around while operating.

[S&A Thomson]

We have a new Bennington 2021 L20 tritoon with a Yamaha 115 on it. Sometimes while operating the boat ,the tach needle is moving around not giving a consistent reading. Sometimes it even goes all the way around the gauge and stays there until shut off. Our dealer is really slow to respond to this issue, and from what I have read ,some say a bad ground, others say the adjustment screw on back of tach is not set properly. Anybody have a similar experience?

 

[RickJay]

I have had the same issue with my 13, it never gets stuck, but is wildly inaccurate. You don’t say if you have the engine mfg’s tach,or the Bennington gauges, but I checked the connector on the back of the tach, and it’s secure, that wouldn’t address if any of the contacts are not making consistent good connections though. I’ve learned to live with it after all these years, and just go by sound. We don’t run high up in the RPM range very often so I’m not worried about it.

 

[S&A Thomson]

Thank-you very much for your response. We have the standard Bennington gauges. I have checked the connection plug on the back of the tach, and it is secure. What I have read from other threads, is to check the black dial on the back of the tach, and adjust it to the number of cylinders on your motor. Ours is a 4-cylinder outboard, and I guess you would be set to the 2P/ 4C setting. 4 cylinders and 2 poles I presume. Is this correct? If it was set differently from the factory, it could cause the gauge to be searching for an accurate reading. Any experienced advice would be appreciated please.

 

[S&A Thomson]

Here is a dark pic of the back of our tachometer. What would be the best way to remove it from the bracket and be able to examine the setting for the number of cylinders? Do I loosen the nuts on the bracket and then loosen the long bolts from the back of the tach itself to let it come a way from the dash and the holding bracket? Then I can see the setting and make an adjustment to correct the issue of a fluctuating tach needle. Any advice would be helpful please.

 

[Remediation]

Take the nuts off the long bolts, the u bracket will come off, push the tach up and the tach can be pulled out of the dash. I just replaced mine.

 

[S&A Thomson]

Thank-you very much for that information. That helps me a lot. It is so nice to have the exchange of info. and tips for pontoon owners to solve problems and improve their boating experience.

 

[Jeff_TH]

Thomsons,

Were you able to remedy the tach needle bouncing issue? We have a 2021 22SV, F115B Yamaha, Bennington gauges. A couple times this summer the tach needle was all over the board. Seemed to settle down as summer wore down. Curious if you found the Bennington guage was not set properly.

Jeff

 

[S&A Thomson]

I have not gotten under the helm to remove the tach, and examine the switch on the back. A bad hip this summer and then replacement surgery has kept me away, but I will do it when I am able , and then give a report back here. Thanks for asking.

 

[S&A Thomson]

Finally had a look at the tach, and removed it from the dashboard. Easy to do as suggested by Remediation in the above post. The photo shows that the factory setting was incorrect, as we have a 4 cylinder Yamaha 115hp. I have reset the to the 4C/2P position ,and will test it out this afternoon. Hopefully this corrects the tach needle bouncing all around. Thank-you again for your assistance and helpful advice, as this problem could be experienced by other owners.

 

[Jeff_TH]

Thomsons,

Thanks for the follow up. If our lake ever ices out <g> we'll get our pontoon out of storage, and take a look at the Bennington tach setting. Thanks also for the photo, that certainly makes things clearer.

Jeff

 

[Vikingstaff]

Finally had a look at the tach, and removed it from the dashboard. Easy to do as suggested by Remediation in the above post. The photo shows that the factory setting was incorrect, as we have a 4 cylinder Yamaha 115hp. I have reset the to the 4C/2P position ,and will test it out this afternoon. Hopefully this corrects the tach needle bouncing all around. Thank-you again for your assistance and helpful advice, as this problem could be experienced by other owners.

Not positive here. However, Is there a chance that the dealership would set this during rigging of the new boat since the motor doesn’t come with it form the factory, but rather arrives separately from motor manufacturer and is added on by the dealership during the rigging process?

Anyone know who sets the tach? At factory by Bennington or dealership during rigging?

Regardless, so glad you found the answers you needed and could make the adjustments to it. Thanks for reporting back to inform others of solution and outcome.

 

[S&A Thomson]

Took our boat out yesterday, and the tach operated perfectly. I was surprised how easy the tach was to remove from the dash, and then put back in after the adjustment was made. Once the nuts come off the back, the bracket comes right off , and then push the tach out through the dash. I think it must have been set at the factory incorrectly, because the dealer knew we had a 4 cylinder motor when they mounted it on the boat. In any case, glad to have resolved the problem, and begin to enjoy the boating season. Thanks again for your help.

 

[BigD]

Took our boat out yesterday, and the tach operated perfectly. I was surprised how easy the tach was to remove from the dash, and then put back in after the adjustment was made. Once the nuts come off the back, the bracket comes right off , and then push the tach out through the dash. I think it must have been set at the factory incorrectly, because the dealer knew we had a 4 cylinder motor when they mounted it on the boat. In any case, glad to have resolved the problem, and begin to enjoy the boating season. Thanks again for your help.

Good news.

 

[S&A Thomson]

OK. So, a little update here. When we took the boat out for longer rides, it seemed that our RPM reading was too high for the engine speed we were going. I did more reading and went onto the website for the maker of our tach, and their chart indicated that we should have set the dial to the 6P position. This is rated for Yamaha outboards. Contrary to the 4C position for 4 cylinders. I changed it yesterday and took it out for a short ride, and it operated now , accurately without the needle bouncing all around. Will test further to make sure it is stable. All this to say, we ended up where we started for the black dial position on the back of our tachometer. For others with tach issues, I hope this experience helps to solve your problems. Thanks again for all your advice.