6Y8 Tach - No Data (06 F250's)

[yamhoss86]

Hi All, my first post here. I'm active on THT, thought I'd post here for more insight.
I have twin 06 F250's. Hooked up to them are two 6Y8 tachs and one Speed/Fuel gauge.
When I first connected them all up, the tachs worked just fine.
Last week the tach stopped transmitting data. The tachs all light up and power up but I don't get any data.
Since then I have checked all connections. as a last resort, I replaced all the colored fuses (on the motors), and for a moment I was able to get data to display after I changed the fuses.
Shortly after I turned off the motors and restarted them and now I still have the same issue (no data).
I checked the fuses and they all seem to be fine.
Any help would be much appreciated. Thank you

[boscoe99]

Are you seeing dashes were rpm numbers used to be? On both tachometers?

[yamhoss86]

Are you seeing dashes were rpm numbers used to be? On both tachometers?

Yes, just dashes

[boscoe99]

Indicates data from the motors are not getting to the tachometers. Now to find out why.

Do you have a hub at the back of the boat to which harnesses from each motor are connected? Then a harness that runs from that hub to a hub at the front of the boat? Then two harnesses that run from that hub to each of the tachometers?

Is the speed/fuel data displaying or not?

[yamhoss86]

Indicates data from the motors are not getting to the tachometers. Now to find out why.

Do you have a hub at the back of the boat to which harnesses from each motor are connected? Then a harness that runs from that hub to a hub at the front of the boat? Then two harnesses that run from that hub to each of the tachometers?

Is the speed/fuel data displaying or not?

I figured that it would be the blue wire. Not sure how to isolate the problem. I have a hub at the transom (2 go to the engines, 1 goes to NEMA and the other is the Bus wire that connects to the hub in my console.
The wire I have coming out from my hub at the console are the three pigtails that connect to the 2 tachs and 1 Speed/Fuel gauge, and one power wire, connected to my ignition. My Speed/Fuel gauge is showing data. When I replaced the 30 amp (green) fuse it worked temporarily. I was reading about this issue everywhere without any clear solution. So frustrating.

[boscoe99]

I know nothing about a green fuse.

Perplexed as to how speed/fuel data is getting to the speed/fuel gauge yet tach data is not. Same bus.

Maybe disconnect one tachometer at a time and see what happens.

Maybe disconnect a tachometer from the helm hub and plug it into the transom hub to see what happens.

Both tachometers failing at the same time is unusual. Particularly if they start working when messing with wiring.

[99yam40]

has to be a bad connection that got better and then bad again after messing with the wiring

[yamhoss86]

Ordered some new pigtails and a bus harness, hopefully this will solve the issue. Will update on Wednesday

[yamhoss86]

Update: Ordered a new Bus Bar, and a new Bus harness.
I changed the harness and bus bars, still having the same issues.
I connected the gauge directly to the motor and didn't get any power at all.
In the process of getting a Yamaha Mech to come to inspect this week.