Z800 was running good. Decided to wash it after a long weekend of riding. Took it off the trailer all was good. Quick spin around the yard no problem. After the wash it will idle fine but falls on it face when trying to accelerate. Dash high beam light is on constant with switch off. LED accent lights are flickering when running,switch is still off. All lights work normal with switch's. What got wet?? Left it out in the sun for two days hoping it would dry up, no chance. Any thoughts??

SWAG!

Is yours a fly-by-wire accelerator system? If so, I would guess TPS got wet. I have a vague memory of a recall on those.

Perhaps the light switches in you dash took in some water as well.

It's an 18. It's got a cable,not fly by wire.

The T-MAP sensor is responsible for telling the ECU when the throttle is opening up. You might want to check the connection on that, though I doubt it would get wet from a wash.  The other thing to check is the high tension leads to see if they are affected by the moisture or otherwise loose.

This could turn out to be quite a hunt and peck operation to find the root cause.
It might be worth a trip to the dealer and have them hook up your machine to a PDU if the problem persists.

Still hunting. I'll post when we find something. All thoughts are welcome. 🤷‍♂️🤷‍♂️

have the same machine, had the same issue  ,   found that plug on fuel pump weather pack was pushed out and letting water in after washing machine,  you could obvious see the seal was pushed out,  hope that may help.