Tach not working correctly

[Northlander]

My rpms are reading higher than I believe they really are. It was reading fine 2 days ago and now its reading on 10 when Im just idling. Should be at 0 like the other day. At WOT it has me at 7000 when the other day I was at about 5800.

What can I do to fix this issue?

[marine_man]

Did you do anything underneath the dash that might have bumped some switches?

marine_man

[Northlander]

No. About all I did was screw a new rod holder on the front of the counsel.

[marine_man]

I'd take a look at the wiring that runs to the tach and make sure something didn't get nicked/pinched under the console.

marine_man

[Northlander]

Checked out wiring from motor to tach and it all looks good. I suppose my 6 year old tach just up and died. Called the parts store and they say they cant get that tach anymore. What? Its only a 6 year old Lund Explorer. They say they can get one that will work for $50-$80. Are you kidding me ?

Marine Man or anyone else you know where I can get a tach for a 04 Lund Explorer ss cheaper than that?

Val you got anything laying around like that?

[marine_man]

What Brand Tach do you have now? It might help to post a picture to try and match one to it...

marine_man

[LMITOUT]

What brand motor do you run? Is it a Yamaha?

Reason I ask is the other day I was cruising across the lake after leaving the landing and looked down at the tach and saw it pointing near 7000. After letting off the throttle a tad the needle would kinda float around between 5-6K and didn't have the sharp movement it had before. Got to my spot, shut it down, fired it back up and everything was fine. At idle I didn't see anything abnormal though.

[Northlander]

What Brand Tach do you have now? It might help to post a picture to try and match one to it...

marine_man

No clue what type. Came with my Lund Explorer. It has a white face and blue back. Funny thing is I went out today and it seemed to work just fine. Could it be getting old and ready to go? Anything motor side that could be causing this?

Ya I also run a 115 4 stroke Yamaha.

[LMITOUT]

Interesting. I run a 90. Weird that it would happen roughly the same time to both of us.

[Valv]

I think it has to do with moon phases. Being Japanese motors they are not exempt from taking off by themselves, but being outboards they only show it in the tachometer.....

I believe your Lund has Teleflex gauges, I don't think they are Faria.

The back of it has a small screw with different settings, try to turn it back and forth a couple or more times, be sure to end where it was before. These are watertight instruments but not waterproof, it could be maybe some moisture did corrode slightly the adjusting part.

[Northlander]

Thanks Valv I will try that.

[vermilionfox]

Sounds like it's time for a new boat and motor!

[Northlander]

I wish but I paid it off this summer and then got a new truck. The boss would not like that idea at all.

[FM_Mike]

I will also jump in here. I have a 2003 mercury 50 hp efi. My tach will also erradicly jump at times. I too have no idea why. One day it will work fine and the next it will jump about 1000 rpm higher than it usually is. Then later on during the day it will go back to normal. On a weeks trip, it will happen a least once. Don't know if tachs wear out or if there may be a wire problem or what. Hopefully (or Not) someone else had this issue and found a cure. Just want to make sure that when the tach does jump that it wont cause a problem with motor being over Rev limit. When mine does this I have always backed my throttle down to make sure it does not go over 6000 RPM. Motor sounds the same as always just the tach that jumps around.

I will continue to follow and hope someone has an idea.

Mike

[Northlander]

Thats exactly what I do. Better safe than sorry. Mine is working just fine now. Maybe I was too close to a mercury filled sturgion or something.

[LMITOUT]

Northlander -

Did you ever resolve this issue? Mine seems to be jumping around every trip out now, but not all the time. One time I'll fire up the engine and motor across the lake and everything is fine, while the next time it is started the tach will be floating all over.

[wastewaterguru]

Plan B is to check the tach output from the voltage regulator. I have seen a lot of merc's where the wires from the stator to the regulator start to "cook" turning the yellow stator wires from yellow to brown. That's usually about the same time the tach starts reading funny!

[traveler]

I have the same issue with mine (150 yammy)...it started acting up last season, and it's doing it again this year, but only occasionally. I pretty much know now where it's running by how it sounds (thanks to lots of prop testing 2 years ago) so it really doesn't concern me too much.

[LMITOUT]

Plan B is to check the tach output from the voltage regulator. I have seen a lot of merc's where the wires from the stator to the regulator start to "cook" turning the yellow stator wires from yellow to brown. That's usually about the same time the tach starts reading funny!

Thank goodness it's not a Mercury!

I've heard that the regulator could be a culprit, but my voltage is rock solid and that was the first thing to check when the tach goes goofy.

I also read to try the tip that Valv posted, which is to work the setting screw back and forth a few times in case there is a little corrosion on the contacts.

Have a feeling it is most likely time for a new tach.

[Grainbelt]

I had the same thing with my Sportfish/190 Mercury I/O. Never had the problem before we got the 9" of rain in a week. Spent 4 days on Mille lacs over the last weekend with problems in the beginning of the trip but not at the end. I think things may have dried out.

[porterhouse]

Every spring I have this problem on my 115 Yammy 4 stroke. I spray WD-40 on the nuts that are on the tachometer (after I loosen them) then I tighten the nuts. Problem goes away.

Good luck!

Brian

[LMITOUT]

Thanks Brian. I'll take a look at that when I dig into it.

[clKiekhafer]

You could try dielectric grease on the tach terminals instead of WD40.

[LMITOUT]

Yeah, if I find that it is a corrosion issue with the terminals I'll probably do something like that to prevent it from happening again.

[LMITOUT]

I took my dash off to look at my tach and found that it doesn't have terminals, but rather a plug connector. I pulled it on and off a few times but it has a rubber o-ring around the plug and is sealed up pretty well so I don't think that fix applies to my case. I did rotate the settings dial back and forth a few times so we'll see if that is the culprit the next time I go out.