Tiny Tach quitting at higher rpms.

[55Crestliner]

My tiny tach is cutting out and displaying the hours (shut down mode) when approaching WOT.<br /><br />A few outings ago, it was dropping to around 2000 or so rpm, when I know the boat was doing about 4500 rpm - based on speed.<br /><br />Any ideas as to what's happening here? Reduce throttle and it displays lower rpm's again.<br /><br />I checked the wires, and they all seem to be the same as when I installed it, and it ran great then.<br /><br />1957 Johnson 18 horse.

 

[Stumpknocker]

Re: Tiny Tach quitting at higher rpms.

55Crestliner, I have a Tiny Tach too. Although mine hasn't displayed your symptoms, I would remind you that the Tiny Tach's are not permanent installions. I was advised by Tiny Tach that the battery installed at the factory is finite with a projected life of maybe 4 or 5 years as I remember. Perhaps your battery is failing? Also see if you can tighten the ground wire.... let us know what you find out. I would also call Tiny Tach as talk to a technician... they are small enough that you can get a live person with little trouble. I'm sure they would have better input than I do. Let us know what happens....

 

[Wreck Rider]

Re: Tiny Tach quitting at higher rpms.

Had the opposite problem with mine, it would display what looked like double the engine speed until about 2K rpm then would drop to what looked like a correct reading. These units have an inductive pickup so I presumed it was sensing the spark wire it was attached to and also a ghost signal from another coil nearby. My solution was to reduce the number of wraps of the pickup wire on the spark wire, and to install a small ferrite core to suppress that second ghost signal.<br /><br />Unfortunately, I haven't had the chance to test it yet so this "fix" may not be one!<br /><br />Just a guess your unit may be missing some of the signals once the engine speed goes up, maybe wrapping the sense wire a couple of extra times will strengthen the signal and get you operating correctly again. If not, sounds like a weak battery or some other completely un-fixable error.<br /><br />Please post back.

 

[jvb]

Re: Tiny Tach quitting at higher rpms.

tiny tach told me to start with 3 wraps, any more may mess up the signal.

 

[55Crestliner]

Re: Tiny Tach quitting at higher rpms.

Thanks for the replies!<br />I fixed the problem. I tried puting another wrap on, didn't fix it. Then, I sent the wires through surgical tubing, to make sure they weren't grounding out or something. (also to just protect from chafing of course). I even put wire loom around the whole length of wire, front to back, to again, protect from damage, and to keep from weird groundings or something - aluminum boat, afterall.<br /><br />All this was time well spent, but didn't fix it. I had the wraps touching each other, so I separated the coils by about a 1/4 inch, and it's working great now! Funny thing is I thought I had it that way originally, but somewhere along the way I guess I wound them tighter. <br /><br />Works great. btw, I just bought the tach in December, I was really hoping the battery was not to blame.

 

[Wreck Rider]

Re: Tiny Tach quitting at higher rpms.

good news!