I have an odd problem with my Brute Force. The symptoms are this:

- Very hard to start
- Stalls when idling
- Backfiring
- Poor acceleration & power
- Top speed ~30mph (should be 60+)
- Engine sounds "slow and loud"

The starting issues and stalling have been happening to some degree since I bought the machine a year ago (bought it new), but when I took it to the dealer last spring they said there was nothing wrong with it, and when they started it up in front of me, it started right up and did not stall.

I was thinking the problems were partly my imagination, and partly just me not knowing how to operate the thing, but the starting and stalling have gotten progressively worse, and in the last month or so all the other issues started (backfiring and sluggishness).

Now here's the strange thing that I just discovered today: When the tank is full the problems pretty much all go away.

When I get down to about 3/4 a tank, I start seeing the problems again, and by the time it reaches half a tank, the machine is running really bad... backfiring a lot, really sluggish, and almost impossible to start.

If I then refill the tank, start it back up, and start driving, all the problems are still there for about a minute or two. But then I get a lot of backfiring for a few seconds, and suddenly the machine takes off and is like new again.

This is a consistent cycle. As long as the tank is full, the machine seems ok. As soon as the gas starts going though, all the problems return.

Any ideas? I've searched these forums and the Internet in general, and I've seen other people who have encountered similar problems. There have been a lot of solutions from different people posted in various places, like "cracked pickup line", "valve switch problem", "dirty injectors", and "bad fuel pump", but nothing I felt was really authoritative.

Anyone know what this could be?

Thanks,
Mike

 

Well, I had an idea until you said the problem goes away with a full tank. Maybe something in the tank blocking the fuel line that floats when the tank is full???? That's a big, big stretch but, I dunno man, that's strange.

What is different between full tank and empty? Pressure on the fuel line. Anybody think of anything else?

 

IS the Vent blocked?

 

mabey there is something inbetween the tank and the carb/throttle body that is blowking fuel flow. so when the tank is full the force of all the fuel in the tank will put enough pressure in the line to get past the blockage....but when that pressure decreses there isn't enough force to push fuel past the block. if its FI then check the fuel pressure. hope you get it figured out.

 

Well, my vote would be for a cracked pickup line. Ever had a hole in a straw? As long as your drink level is above the hole, all is fine. As soon as the level drops below the whole, then it is hard to drink with. It sounds to me like you are getting air in the fuel line when the fuel level drops. That would explain slugishness and sputtering, poor idle, etc... The backfire is a little more interesting in that that is usually unburned fuel in the exhaust and indicative of a rich mixture, but a whole in the fuel pickup would probably cause a lean condition. Do you notice the machine running hot when it starts misbehaving?

 

This sounds very plausible, and is in line with what the analysis I found at this link. I didn't have any idea what a "cracked pickup line" when I read the other guy's post, but the way you describe it makes sense to me.

About running hot: I've suspected the machine has been running hot since I bought it, but since this is my first experience with an ATV, I don't have anything to compare it to.

I'm a little irritated at my dealer right now. Yesterday after I posted here I called and talked to the mechanic there, and he told me "just keep it filled up if that solves the problem". This machine is barely a year old and for $5500 I expect it to run without this kind of headache.

Here's a related question: If the pickup line is indeed cracked, how hard might this have been on the rest of the machine? The starter has definitely had a lot more wear on it than it should have (requiring several minutes to get started every day), but what about the engine in general? I've had to keep the idle cranked up to max just to keep the machine from stalling constantly, and I suspect the engine has been running hot since the day I got it.

One of the things the dealer was really adamant about was not running the machine past half throttle for the first 10 hours. Is it possible that this cracked pickup line would have negated that, or that running at high idle or with all the air in the fuel from a cracked line would have put a lot of wear on the engine during the months I've been driving it?

Also, if it does turn out to be a cracked pickup line, is there anything beyond a routine maintenance check and replacing the line that I should have done? I guess what I'm getting at is... should I be concerned about a significantly shortened engine life, or any other problems down the road as a result of this? Should the engine be taken apart or anything like that? Should I get anything else done while the machine is still under warranty?

Note that I don't really know what I'm talking about mechanically -- just trying to figure out if this machine is worth making more payments on, or if it's toast... I've only had to pay $50/month so far due to a promo, and the dealer has been flippant about even looking at the machine when I've mentioned problems in the past (hard to start, conks out when idling, etc), so it's not like I'd have any reservation about walking away from it if they don't fix it right this time.

Many thanks to all. I don't know how we got along before the Internet.

 

Oh, another question: Is the pickup line something I can check myself without having to take it into the dealer? I don't know a whole lot about engine repair, but I'm reasonably competent if I have instructions. I'm working on getting a service manual from another forum right now, but having trouble with the download. Is this something that could be easily explained in words?

 

Well, I got the ATV to the dealer yesterday and the mechanic is convinced that the engine is "gummed up" from putting gas with ethanol in it. He said the reason it was running so poorly and sounding "slow" was that it was only running on one cylinder (which does seem to explain everything), and that it was the other cylinder getting freed up that would cause it to suddenly start running right again.

At this point I have no reason not to accept his analysis, because after some more experimenting yesterday with different levels of gas in the tank, I realized that if it was the pickup line then it should have started running smooth pretty much *immediately*, but that wasn't the case. It usually took a minute or two.

So now I'm now thinking it was either just coincidence that it would start running right once I topped it off (seems a little unlikely because it happened three times), or it had something to do with getting really fresh gas into the tank and cycling through the engine.

Whatever the case, I'm going to be out $400 to have the fuel system cleaned, and the mechanic said that I should put in ethanol-free gas, or put fuel stabilizer in the tank. But the nearest gas station that sells completely ethanol-free gas is almost 40 minutes away...

Is this normal for Kawasaki ATVs? There is a warning on the machine not to use E85, but the gas I've been putting in it just says "may contain up to 10% ethanol" on the pump.

Are these things really this delicate with regards to the fuel that you give them? Nothing else I own seems to have any problem with standard gas (cars, trucks, mowers, chainsaws, etc), and my neighbor says he just uses standard gas in his Arctic Cat ATV and has never had any problems like this. This is going to be kind of a hassle for me, and even with fuel stabilizer I'm always going to be wondering when the next $400 bill is going to be coming to clean out the fuel system again.

Any thoughts?

 

ya know my 06 did this to me about a year ago and ever since i had it rejetted the problem is solved. It used to get really hot on your leg while riding,and most of the time when i would go to start it, it would start hard and had no power and ran like crap. I would take it out on the hard road and literrally hold the throttle all the way in until it would backfire and come out of it. Not saying that is the problem but sounds exactly like what mine did until i got it rejetted using the dyno jet kit. good luck rammy

 

Is your Brute carborated or fuel injected? My dealer warned me about running even 10% ethanol in my Prairie. He said the problem is the ethanol eats the plastic tank and gums up the fuel system. He also said since I have a carb it would take a few years; if I had injectors I can see it happening faster.

I wonder if anyone makes a coating for the inside of plastic tanks to keep this from happening???