I have a Suzuki Quadrunner (99 I think). It starts fine and runs well until about half throttle or higher, and from there it bogs down and just chugs. I've had the carb out and cleaned it several times and my service guy did it also. No avail.

I've tried new plugs, and ethanol free gas. Nada.

The odd thing is, if I leave it alone over the winter, or for a long period of time, it will run fine the first time. Then it goes back to bogging down at half throttle.

Any ideas?

PS: I try to do my own work if I can, but I am far from a skilled mechanic.

 

I don't know if this helps, but if I rev the engine in neutral, it will bog down past half throttle like usual, but will also backfire.

 

when was the last time you cleaned the air filter?

 

It's been awhile. The filter does not look bad but I'll try anything.

 

Have you tried running it with the headlights on?

The reason I ask is because the voltage regulators can go bad on these atv's. When they do, they usually over volt the system, and it goes into a "limp mode" where it sounds just like a rev limiter has kicked in. When you turn the lights on, it is usually enough drain on the system to bring the voltage back to normal and allow it to run correctly. If the regulator is bad enough though, I have heard this wont fix it either.

I have been having some voltage regulator issues with mine and it could seem like a carburetor issue, but is not. If the headlights dont fix the problem, pull the front plastic off and unplug the voltage regulator. It is right under the handle bars and right behind the vents in the front plastic. Unplugging it will cure the problem if the regulator is bad, but the charging system wont charge so you will want to replace it.

It may be running fine after you let it sit for a long time because the battery is draining as it sits, so it runs normally until it gets charged back up and the system is over volted/amped again.

Try your lights first and if its no better, then try unplugging the regulator. You may just find your problem...

 

I'll give it a try. Thanks

 

hi, did that work? i got the same problem today. will idle? but when your rev it over 1/3 it will start 'chugging' like its just about to cut out as or you could say not idling fast enough? i need this sorted as i was out on the farm today and it died in the field and started doing this?, need to find out as ive left it out there!? with a tarpaulin on it ????

 

That did work! I ran it around the fields a few times with the lights on, and it ran well. I turned the lights off and after about 100 yards, started to chug. Lights back on, and it began working fine again.

I'll pull the regulator and see if I can find a replacement.

Thanks very much.

 

Good deal, I'm glad to hear that was your problem. I am having the same problem with mine. I bought it with a blown engine and then rebuilt it. It ran fine for a while but then started doing the cutting out thing. I found the regulator was the issue but I am having trouble fixing it. Any time I unplug the regulator it runs fine. I have bought two used regulators from eBay that were supposed to be good. The first one worked great for the first 30 minutes or so then started doing the same thing the other did. The second regulator I bought never did make a difference. So I'm wondering now if I have a bad connection somewhere in the wiring or what. I'm thinking it's possible all 3 regulators are good but that I have a bad connection.

One thing I have found with mine as well is that I can run it 20 minutes or so with the lights on and when I turn them off then it runs normally. It never runs right on the first start of the day though. You may want to check all your wiring connections before buying a regulator. I can keep you updated on what I find with mine but it is definitely either a regulator or connector issue.