If you're looking at [INSTANT] MPG instead of [AVG], it's going to change second to second, change the display to [AVG]. Keep in mind that the [AVG] is tied to the trip and will zero when you zero the trip and change as you put more miles on the bike on that [TRIP] until you zero it. There are 2 [TRIP] and [A] and that will have different avg. mpg if they were zeroed at different distances. Temp will fluctuate some while riding with engine power, air conditions, electric fan turning on and off. The fill gauge is an actual reading from a sender in the tank, while the [RANGE] is computer guestimate and affected by every thing you could imagine and may be still learning. Do you live somewhere they switch to a winter mix for gasoline? Are they being more twitchy, or are you just noticing that they move around now? Check all of the connectors are tight including your battery terminal, weird voltages from a loose battery connector will drive you nuts before you realize. Given the fuel gauge, the only semi-stable value with a direct sensor reading seems to be giving sane output according to you and the dealer gave it an OK, I'd ride the bike and pay attention to the road unless you're having an actual malfunction. The shop manual is $100 well spent, 2 large volumes, and goes into great detail how to test everything including the ECU and ABS systems if you don't believe in the dealership.

 

I wonder if your screen has a loose connection somewhere, given that many data points are giving spurious readings. Eg. temp is unrelated to fuel economy which is based on speed so, what's the common thing with these two readings?

Can you see the wiring loom that goes into the display? Have you fitted any accessories (driving lights, for example) that when being installed you might've disturbed some wiring?

Or maybe something wasn't securely connected or attached during assembly and vibration has caused something to come adrift?

Start with an easy one - the front ABS sensor where the bike's speed is measured and then look at the harder stuff next.

Good luck with it.

 

I wonder if your screen has a loose connection somewhere, given that many data points are giving spurious readings.

Yep, this just screams "loose instrument panel connector".

 

Talked to the dealer today. Not a loose connection. Tech talked to Suzuki and they said they would authorize replacement of the fuel sending unit. Told him that would not address the issue with the engine temp bouncing around. Guess he was not told by the service manager about that part of the problem. Said he was going to investigate further…