Tachometer question

[majoma]

When I started the engines this morning on my 2000 340 and with both engines at idle, the tachometer for the port engines read 750 RPM while the starboard one was at 2000 RPM.
The sync indicator was right in the middle. I never had this problem before. I went out for a ride and the tachometer on the starboard engine always was much higher than the port one even with the sync indicator reading equal RPM.
What should I do? Replace it or try to fix it.
Thanks

 

[JVM225]

There is an adjustment place on the back of the tach that a small slotted screwdriver fits in.
It’s so the tach can be used with different engines (4cyl, 6cyl, 8cyl)
Make note of the position yours is in.
Use a screwdriver to turn the adjuster back and forth several times and then return it to it’s original position.
That might take care of it.
Had the same thing on my old boat, and had it again with this one.
Was able to solve it on both boats by using the method I described. Had to do it every year or so on the old boat and expect to have to do the same on this one.
Hmmm.......Oddly enough, it was the starboard tach on my old boat and this one too.
Maybe the starboard tach Gods are screwing with us......?

 

[majoma]

Thank you for your quick reply and suggestion. I will try it as soon as I can.

 

[NotHerDecision]

The tacos on our boats are notoriously bad. I have replaced both of mine.

 

[suss1173]

Towards the end of the summer my tach started doing the same thing as the OP's. I'll have to try turning the screw a few times in the spring.

Hopefully that will sort mine out.

 

[Skuza]

Sometimes a well palmed smack right on the gauges jars it back as well.
Not responsible for cuts or broken tach lens!

 

[TNT8808]

I tried everything, including new tachs and could never quite get them to my liking. I ended up modifying some broken tachs, while keeping the originals for the next owner (so they could verify hours). I opened the back, and inserted Aetna digital tachs. Here's a pic of how it turned out. They were a perfect fit, and once I turned on the sync they stayed within 1 RPM of each other. (pic was taken while idling out to Lake Michigan through the channel)

-Tom

 

[majoma]

They look very nice

 

[JMS23]

I tried everything, including new tachs and could never quite get them to my liking. I ended up modifying some broken tachs, while keeping the originals for the next owner (so they could verify hours). I opened the back, and inserted Aetna digital tachs. Here's a pic of how it turned out. They were a perfect fit, and once I turned on the sync they stayed within 1 RPM of each other. (pic was taken while idling out to Lake Michigan through the channel)

-TomView attachment 51937

did you have to the dip switches? I installed the 8905r and bout read 9999. any suggestions?