Home Forums Hunting & Shooting Hunter's Campfire UTV Problem

I've got a mechanical issue with my 2009 Yamaha Rhino (450) that I can't figure out. When I run at high speed, in hot weather, for several miles it will SOMETIMES idle rough when stopped. The problem will only last a few minutes. No starting, or running problems, just the rough idle when it's hot. I've done everything I know to do and consulted all of my buddies, but we're at loss. The situation is not a real problem, but is really perplexing.

Any ideas?

Trash in your fuel tank, maybe?

it's that ethanol crap!!

Fresh fuel? Maybe try some premium.

Not familiar with that model, but is the fan motor kicking on? My old Kodiak 400 would do the same before replacing the cooling fan. It was getting hot enough to cause some pre-detonation. Only issue I ever had with it.

Is it fuel injected ? I've seen some bikes that want to "reset" the fuel curve after a hard run.

No such problems on my 2011 450 Griz.

Good luck.

It'll be your "roll over protection valve".
Clean it or replace....or remove and replace with an inline fuel filter.

Most likely anyway......

Quit being cheap and buy a new 2016.......
They run great.

Put off that body cam purchase for a year and treat yourself.





or clean your air filter.

Fuel injected?

so when you're cruising along a t high power/speed, you've got plenty of cooling airflow. You stop, machine is still hot, but no cooling air flow.....vapor lock?

Go catch a crook.

sir, do you let it sit 2-3 weeks between uses? or do you run it all the time? if you let it sit a while between runs, try a product called Star Tech for a fuel additive. designed for ethanol problems. works great in chain saws and my gator.

-tom

Fuel injected engines frequently need their throttle bodies cleaned. I'd look at that, first.

As was said, the problem may be with the fuel intake, but it is almost certainly electronic at its root.

or
"Under the seat, above the gas tank, is a metal plate. This plate protects the electrical connectors and tank fittings. The tank vent line is routed over top of the electrical connectors, beneath the metal plate.

When somebody sits in the seat, the metal plate is flexed down, which presses on the vent line, and eventually chokes it off.

It's a simple matter of re-routing the vent line so it can't get squished."

The above 2 items are known issues with the yamahas.........

Mine did it and I fixed it by cleaning out the roll-over-protection valve..........

Flipped mine with my wife on the back going down a steep trail last year.

Speed was less than average walking speed and my nose was against the gas cap in the blink of an eye. First thing I did was sniff for gas. Nope.

I'm actually thankful for enginerrs at moments like that.

Glad my wife was with me as I was pinned under the bike. and she helped me out fom under.

Being bear bait up on the mountain ain't a groovy feeling.

Thanks all. It is not fuel injected. I run premium, non-ethanol fuel. It do suspect a vacuum-lock, but it only happens when very hot, so it's difficult to check sources, because you "make" the problem happen unless you get the engine hot. It is definitely heat related and doesn't matter if there is a passenger, or not, so I suspect something is expanding somewhere to to cause it. I will look into the roll-over-protection valve. I've never even heard of that.

Also, it doesn't have anything to do with the venting of the gas tank, or fuel lines. Boiling gas in the carb?

Going through carb. problems with my Honda Rancher 4x4 now. From ethanol, of course. I used an additive too..

Rhino I have idles a bit rough too, but it's a 700 EFI.

My 07 660 has idled rough from day one,anytime/all of the time when at idle. Cold, hot it just doesn't seem to matter.

Instead of going directly from high speeds/rpms into an idle mode, decrease the speed and run at a lower rpm for a bit before letting it idle. May or may not make a difference, but it's easy enough to give it a try.

It doesn't work. I keep hoping whatever it is will get worse (dumb, I suppose) so I can figure out what it is. The fact that it only does it when it's really hot, makes it tough to "check as you go".