I have read the other threads on range problems but mine seems to be a different ball of wax.

I'm riding a 07 KLX250S, 500kms on the clock, mods are an FMF exhaust, carb jetted to match, airbox opened and a 13 tooth front sprocket.

Now my problem is I went out with a buddy on my first long ride and the bike died at 100km(60 miles) on the trip-meter. I got another 20km(12 miles) out of the tank on reserve. Odd. Fortunately I was able to borrow fuel to get going again.

I did notice, before I switched it to reserve, that the fuel filter installed under the fuel switch was bone dry. Switching to reserve got the fuel filter filled back up. And once it stalled out after running on reserve I noticed what seemed to be a lot of fuel still in the tank. I always imagined that when running on reserve, the bike would die when the tank was practically bone dry.

Even odder... While pulling into the gas station, running on reserve, it died. On the ride to the gas station, it started stuttering in "on" so I reached down and switched the fuel to reserve while riding. So the tank should have been pretty empty. But it only took on 3.5 liters(1.4 US gal) at the pump. The capacity is 7.7L (2.04 gal). So that means there was about 4.2L splashing around in there when it died on reserve.

Also a quick calculation shows that I was getting about 65mpg on the fuel actually burnned.

A buddy suggested that the fuel filter may be restricting flow enough that when the tank gets low the pull from the carb isn't strong enough to overcome it. No fuel pump so I assume it's gravity right?

So... I can try taking out the fuel filter and hope for the best but I'd rather not run out of fuel in the middle of nowhere again. Especially if there was something else that is more likely the problem. Something wrong inside the tank? Carb problem?

Any ideas?

 

Look for any kinking at the fuel lines. It won't take much to foul things up. If a fuel filter was installed inline, and the fuel line was not trimmed to a new length, it's very very possible the line is kinked. The fuel lines are not very well made in my opinion. They are oddly shaped, too long, and are brittle too. Yes, it's a gravity feed system. Also be sure the tank vent lines are not kinked or squished flat between something.

 

Thanks for the idea. Just went and took another look and the lines are routed smooth. No kinks or flat spots. I did notice though that the filter is below the fuel inlet on the side of the carb. So the fuel would have to have to be sucked up to the carb about an inch or two. Could that be all that the problem is?

I should also note that the fuel filter is crystal clear and clean. If it's restricting fuel it's not because it's dirty that's for sure.

BTW... the filter is on there because I foresee a lot of bush refueling in less than sanitary conditions. I'd rather change a filter than pull a carb.

 

what i would do.

replace fuel filter and try and get the fuel line to only ever descends. in other word remove any dips in the line.

also check that the fuel is flowing on "on" and "reserve" by removing the fuel hose after the fuel filter.

 

Check to be sure that your petcock is operating properly and that you are getting a full stream from both the open and res settings.

 

Hey Freeze welcome to the forums. Here's my solution.

 

That issue of the fuel line or filter dipping slightly below the carb inlet has never been an issue for me on any of my bikes...KLR's, XR's, and my KLX. Either the running of a fuel filter and/or running aftermarket tanks has caused me to run some lower fuel line feeds to my carb inlets, and I've had no problems. Now, "slightly below" can be a big difference to different people, and one should use common sense here. The fuel level in the tank and its orientation to the tank petcock and the carb inlet is the critical element. These bikes don't drink enough fuel at any rate to challenge this issue. I'm no physics professor, but you can count on the gravity flow of the fuel to easily overcome a slightly lower hose or filter placement to the carb inlet. Just don't go silly with it. I don't think this is your problem. The suggestions of a kinked/smashed inlet or vent line are good things to check. However, you usually don't have to get low on fuel for these issues to surface. I'm wondering about your standpipe condition in the tank...dirty, bent, etc.

 

Thanks for the ideas.

I filled the tank the other night and disconnected the fuel line at the carb. I then ran a long line into a bucket on the floor. The fuel ran from the tank through the filter just fine. And drained the tank basically dry when on reserve.

But one thing I didn't take into account at the time was I was basically creating a three foot drop siphon. So that test only proved that the lines are capable of draining the tank.

Either way I took the filter off, I could blow through it almost as if it weren't there by the way, and put a line straight from the carb to the fuel valve. I did find out in this process that there is a tiny filter screen in the fuel line right before the carb. Not sure how effective it is but I left it in there.

Deej... thanks for the MSR bottle idea. That was what actually got me out of the bush... sort of. I made a two bottle mount and was testing how one bottle survived the ride. One bottle got me half way out... oops.

The MSR bottle is a great idea and I'm taking two on every long trip... but I need to figure out the real problem that is causing my bike to starve with 4L of fuel still in the tank.

Fingers crossed that it was just the filter and/or the fuel line dipping low. I'm going to do a test run soon... close to a gas station

 

Just an idea but are the tank breathers clear?

I had a fuel issue last weekend with my Nomad tank.
The breather hose was kinked and so even though there was plenty of fuel in the tank, air could not get in so fuel stopped flowing out.

 

I hit reserve usually right at 88 miles, never tried to see how much farther the bike will go after that. How close to the top of the tank are you filling it? What are your RPM's at say 60mph. I'm running close to 7 grand at 60 with the 13-45 gears.