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View Full Version : Backfiring, stalling, sluggish performance...



mpc220
01-08-2010, 12:34 PM
I have an odd problem with my Kawasaki 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 seems to be 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

honda300EXtreme
01-12-2010, 08:00 PM
bump, i got nothing, but i would like to know what the cause is

did you figure it out yet?

450R NOOB
01-13-2010, 02:44 PM
Try running it without the gas cap when it messes up. Maybe a clogged vent?

Smoker
01-15-2010, 02:43 PM
Dump your tank, pull the tank off, pull the petcock off and look at the screen attached to the petcock. A good place to start if you think it's fuel related. Dirt or water can hang out and cause headaches. If you think it's a cracked line or hole somewhere, buy a can of engine starting fluid and spray it around the suspect lines while it's running, if it revs up, you have a leak somewhere. Problems like that will make you want to toss a match at your quad but once you figure it out, a good learning experience.