bouncing tachometer?-gctid825068

[bcarli1111]

We just came back from a three week trip and part way through the port tach started bouncing all over the place. There seemed no rhythm or reason as to why.The only thing I noticed was that it didn't start bouncing when I started the motor but after the engine was running for a while..also some time it would suddenly stop jumping around and read fine. I wonder if there is a sensor someplace that may need replacing? any ideas?

thanks

[builderdude]

Loose wire connection, probably behind the gauge itself.

[bal734]

Check for corrosion on the wire at the sender.

[floatyerboat]

I've got 4 tachs jumping all over the place. If you can, swap wires and put your starboard wires on your port tach. If the wires wont reach use some jumper wires and see what happens to your port tach. I've been in touch with Faria Instruments and one of their engineers said maybe my tachs are just old and warn out.

[Nauti_Mike]

Sometime by cycling the cylinder selector on the back between 4/6/8 a few time corrects this.

[Mr._Darcy]

I don't know what boat, or engines you have,,, (filling out your profile page would solve that problem) however if you have one of those multi pin electrical connectors going to your engines, try the wiggle and tug method to see if there are bad connections. Corrosion can be a cause of that too. This is in addition to the other suggestions already given.

Greg

[Rick_Kenyon]

Mine was doing that for a while. Sprayed the wire connections and the rear of the tach with electronic parts cleaner. Also sprayed the plug connection on the coil. Eventually the tach quit completely. New Faria tach on eBay was $95. If it's out of warranty, Faria wants $100 to repair it. Cheaper just to buy new.

[Centerline2]

"Nauti Mike" post=825094 wrote:
Sometime by cycling the cylinder selector on the back between 4/6/8 a few time corrects this.

correct...

I just fixed my upper tach doing this.

[bcarli1111]

where is the cylinder selector located? Is it on the back of the tach itself?....checked wire connections and they all seemed good

[Nauti_Mike]

"bcarli1111" post=826281 wrote:
where is the cylinder selector located? Is it on the back of the tach itself?....checked wire connections and they all seemed good

Yes on the backside of the tach.

[bcarli]

found the cylinder selector on the back of the tach. It doesn't seem to be adjustable from the back. Do I have to remove the tach to switch through the different cylinder settings? There is an indent in the tach next to the cylinder selector that looks like a colored wheel? I haven't forced it...so what is the correct way to change the cylinder setting?
thanks

[Nauti_Mike]

Post a picture. Typically you use a small flat blade screwdriver to turn the selector.

[mlewis100]

My starboard tach bounces on upper and lower helms consistantly but generally once it is warmed up, not usually when cold or during the warm-up. I think it might be a damaged wire in an awkward location but I have to track it down to confirm it...

[guntar]

Mine were jumping as well. No rhyme or reason to it. I pulled the face dash board to gain access to the back side and removed the plug from each and cleaned with wire bush the contacts and the plug sockets with qtip and alcohol and put it back together and they work great. Steady and true. Bal734 told me to do this and he was dead on...