[Hal]

A friend and myself bought new Z1000's about a month ago from different dealers. He just called and said he had an issue with his going into what seems to be a 'limp' mode, loosing power. He drove it back to camp about a mile at very reduced speeds 20-25 mph and when he got there the exhaust was red hot, hot enough to start the ruber exhaust hanger on fire.  Sounds like an extreme lean mixture issue but why? He had been driving at home @ around 3500' elevation, trailered it to Quartzsite where he's around 600'. This happened on the first run at the lower elevation. I'd guess the computor hadn't adjusted to the altitude but I thought that was supposed to be just about instant.
After the one incident he hasn't had any repeat and the car seems to run great.
I told him to bring it back to his dealer but he's got a little sideways with them and needs to get it to another dealer for service.
Any thoughts out there?
Thanks, Hal

[NMKawierider]

Because I don't believe there is any limp mode on these my first thoughts were as yours are-extremely lean mixture...and because there were some tank check valve problems getting stuck shut and open, my mind wanders to that. Shut would cause a vacuum on the tank and drop pump output. That would drop injector pressure and volume which would lean it way out. Then excess unburned hydrocarbons in the exhaust would then burn and make everything all the way to the discharge red hot. Other things can cause this too but hopefully...what every caused this didn't hurt the pistons and valves.

[Hal]

The check valve sounds like it probably caused the problem-good idea. If the valve were stuck shut the tank could have had quite a vacuum on it from the trip from Kingman (3800') to Quartzsite (600') elevation. I think I'll recomend he open the gas cap when he first arrives and see it there is any vacuum. The problem with issues like this are that they seldom are repeatable when brought in for service. We'll see how it works out as the car runs great now. Thanks for the imput,
Hal

[Hutcho]

I had an issue with loss of power and have noticed the exhaust getting very hot too, as you talk about a fuel vacuum and opening the filler cap.. I had a thought, could this issue be caused by over filling the fuel tank (IE filling to the top of the filler pipe). It makes sense that on a hot day or maybe at a different altitude the fuel expands putting pressure on the pump? Just thinking out loud. Interested to get your (more mechanically minded) views.
When I think back, I know I over filled my fuel as I wanted to ensure I had as much fuel in it as possible. And I have also since read that you shouldn’t fill to the top of the filler pipe and maybe this is the reason.