O2 guage
 

I installed an INNOVATE O2 gauge two weeks ago. I went out boating last Sunday and the gauge never went off of 8 AFR.
I am getting a light sooting on the back of the boat. If I am getting sooting is that lower than an 8 AFR?
The sensor is good because tonight I connected my laptop to the control and it reads 20.9 O2 without the engine running.

If you are running a true 8afr that is pig fat? The guage should move quite a bit from idle usually in the 13 or 14 range to 11.5 to 12 range at wot some like it richer or leaner.

The gauge NEVER moves off of 8 after initiation when You turn the key. ( the gauge goes full scale and then to 8 on initial turn of the key.)
I am going to take the laptop with me next time out. That way I can see what the O2 reading is.

It should be 22.4 with the engine not running.

The o2 sensors I`m familiar with do not read richer than 9.0AFR.
Your plugs would be pretty black. If it does not more off 8 something is wrong with the gauge/o2

innovate will be 20.9 in free air

also never calibrate in the exhaust pipe but in open air.

sounds like you are either pig rich or gauge/sensor is acting up. Have you pulled a plug, because at 8.0 it should look real nasty.

Is the fuel mileage really crappy?

At 8:1 AFR, you should damn near be able to watch the gas gauge move...

Im thinking your sensor is dead.

I concur with most above. The sensor is not calibrated or is bad. MUST do free air calibration. I actually don't believe your engine would physically operate with an AFR of 8:1. I've seen the high tens on initial tuning and the fumes were eye watering plus the engine idled like a nasty top fuel motor. The IAC surged like crazy trying to keep up.