I have about 15 hrs on my new BF 750, and I've noticed quite a bit of fuel squirting out of the vent tubes that are mounted on the steering stem...

Literally, squirting out on to the front of the airbox. I don't really have any special circumstances when it happens...

Any ideas? I will try to do more testing/investigating tomorrow...

I don't really want to take it to the dealer unless it is a serious problem...

Here are the facts:

- '08 BF 750 4x4i
- elevation between 9000 and 10,000 feet
- mostly mountain trails

any info greatly appreciated

 

usually happens when its really full and the gas expands, it comes out the vent tubes...

 

if you think there is a problem then you better take it because it is still under warranty

 

I'll give it a couple days, to see if that is the case. I'll let the fuel level get down a bit... It was happening w/ only 3/4 tank, though...

THis is the only example of when I actually saw it happen:

I was coming down my driveway (1 mile in length, 600 foot drop in elevation), and I turned left, off camber to the right, and as soon as I got back on the gas, it squirted out from the steering stem vent tubes and onto the airbox cover. That was the only time I actually saw it happen, but I could smell fuel at times during my ride in the woods...

 

Ok, Here's the deal...

I took my BF 750 to the dealer today , and explained everything...

I left it with them for about 15 min before they got back to me...

The tech got on the line to kawasaki, and they immediately knew what the problem was...

Basically, the fuel tank vent goes into the rightside framerail, and then there is a vent hose connected at the front near the steering stem which vents right under the instrument cluster. If you fill the fuel tank even a hair above the bottom of the filler neck or even a hair above when the gauge says full, fuel will go into the framerail. Then, the only way for it to come out is when it is sloshing around and squirts out the vent tube under the cluster...

Here's the fix:

1.) Be very careful not to "overfill" the tank... Basically, when the gauge says full, stop...

2.) They drilled a very small hole at the very rear of the rightside framerail... Therefore "if" any fuel gets into the frame, it will immediately drain out the back (which is alot safer than right above the front cylinder exhaust...)

I'm glad that it was something simple - I was in and out of the dealer in less than an hour...

Hope this saves others some time and frustration...

~Troy

 

Comment on few things.
1). Filling the Gas
I always fill up to the gas cap on my 750 and never experience the problem you are describing. The fuel tank /vent design is same or very similar whether it is carbed or EFI 750 or BF or P650.
2). Drilling a hole on the frame to divert the leaking fuel is not the right way. It's just a bad band-aid. You are just not seeing the problem but it is still there.
2). Fuel Vent One-Way Check Valve
This valve is supposed to prevent the fuel going up to the handle bar stem area when under fuel tank inside pressure is under 5 psi. It opens up at about 5 psi to avoid excessive expansion/bursting of the plastic fuel tank. It is one way direction under 5 psi so that air is coming into the fuel tank whenever fuel is pumped out. If the valve is not doing its job, the fuel will escape out even at under 5 psi OR if it is installed backward, you would see fuel coming out especially when overfilled. You should check the check valve.

 

Well, this happened to me. I need to get it fixed, but I agree that drilling a hole in the frame doesn't sound like the correct answer. What should I do. My dealer just started selling Kawie, so I dont think they will know how to fix it.

Suggestions?

Thanks
JAM

 

Check to make sure that the check valve is installed in the correct direction. An arrow mark on the check-valve body should point toward the fuel tank. If OK, check to make sure it is functional - opnes up at around 5-psi when pressures is applied from the fuel tank side.

 

I don't have the problem on my 08 and fill it up to just above the spout line, I do pull the white liner out inside each time I fill it and then put it back in afterwards....but do not have fuel coming out my vent line...

 

There are 3 main factors contributing to this condition:
1). Pressure building up inside the tand due to gas expansion by increase in temperature - by the equation P=nRT/V. Sicne the n, R and V are constant in this case, the only variable is the T.
2). Fuel level - how close is it to the vent nipple on top of the gas tank.
3). One-way vent check valve function.