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Dirty Fuel Filter

By Hans Schmid,
in YZ400F/426F/450F/450FX

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Grand Master

Hans Schmid

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Figure I should post up the importance of using a fuel sock or such. Since day 1 on my 2015 YZ450F I haven't used any strainer or such to keep my fuel clean. I am cautious about what I'm dumping in the tank but after 100s of tanks of fuel stuff is bound to get in.

Recently I switch fuel tanks and with out thinking twice I bolted everything up. Unfortunately there must have been dust built up which led to some problems.

First issue was hard starting. My one kick machine became a 3-4 kick machine. Combined with that came an intermittent bog. Pretty similar feeling as running out of fuel. This all came with the first tank of fuel. Not even half empty and the bike acted like it was outta fuel...

Second ride and fill up led for even bigger issues, a major bog and eventually the bike would not rev past 1/4 throttle. Worried as hell I limped her back to the truck and shut it off.

Back at home I hooked up my tuner and yup, no codes shown but a poor running machine.

Figured I would start with my guy instinct of a plugged fuel filter and work at her. I did nothing outside of cleaning the fuel filter to make sure it was just one thing at a time. There is no point on making multiple changes outside of checking the obvious things such as plugged in connectors. I pulled the tank, dropped the fuel, pulled the pump and got to work.

Pulling the pump apart when it isn't designed to be pulled apart is a major PITA. A few one way tabs and a hose that is heated and pressed on don't make for a easy task. With a little Canadian ingenuity I managed to get it apart. I did have to cut the internal fuel line learning later it is nylon and not the easiest to get your hands on. That all being said, a healthy dose of brake clean, water and compressed air I was able to changed a blackened filter into nice and white.

Letting the filter dry overnight, carefully putting the pump back together, cleaning the fuel tank twice over etc etc. With fresh new fuel I fired her up and she seemed to run excellent on the stand. The real test is in the field though.

Headed out today and it's perfect and in my seat of the pants test the bike feels a bit more responsive and powerful. Starting is back to 1 kick again too.

So, all that being said, start with the obvious first and hopefully my symptoms and fix can guide you through a similar problem you might have in the future. Clean fuel and a fuel sock will definitely help too...

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Grand Master

Hans Schmid

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What did you end up using for the fuel line in the tank? Also what's the diameter? I'd like to have some on hand when I take mine apart. I'm at over 200 hours now and I'm thinking she's due for a cleaning, lol.

Same fuel line they use in power-saws. Allows them to be run at any angle so they are always in fuel...

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damnbiker94

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I use a funnel called Mr Funnel. Has a filtration system and its excellent. Can be bought at various auto parts stores. Only problem that i have with it is that you can't see inside the tank as you fill it so you have to keep checking the level to avoid overflowing the tank. http://www.walmart.com/ip/Hopkins-Mr.-Funnel-F8C-Con-Fuel-Filter-Funnel/24200899

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TN Dirt Rider

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I had kind of a similar experience with the carb on my YZ250. Start of a big 3 day fun ride at Loretta Lynn's last year. Made one loop, no problem. Decided to switch to my stock tank instead of my oversize. Rode a bit and came back to my camper and gas was pouring out of the overflow. Fought with it the rest of the weekend, pulling carb about about 4 times trying to get it cleaned out.

In my case the issue was stupidity. I had 2 tanks, but only one cap. So the tank I wasn't using was sitting in my garage open. Over time it had gotten dust and who knows what else in it. After that I bought a 2nd cap and keep both closed all the time.

Doesn't take all that much dirt to cause big problems. Sure screwed my weekend up.

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Grand Master

Hans Schmid

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An update is much needed!

After a few tanks of fuel and multiple rides the bike ran better then ever, but...Cresting the top of a very steep climb the bike just died. Multiple kicks later and not even a hint of firing. In my head all I could do was think of the worst. Fuel pump? Stator? CDI? Who knew!?

We found a stick and my buddy pulled me down the trail for a bit and after awhile I pushed her to the road. At that point my buddy gave me a ride back to my truck and I drove back to pick up the bike.

Her she lied dead!20160315_133628_zpse95ayqiv.jpg

So, at home I pulled the tank and tested the pump. A small buzzing was present so that was good. Upon disconnecting the fuel line gas just started pissing out. This is not normal as the pump wasn't running. Draining the fuel tank and pulling the pump the problem became obvious. The line that I had used, though fuel safe was not pressure safe and eventually burst.

I'm happy this happened so soon and where it did. With our series kick off happening in a week something like this over a 80ft double could be devastating. A quick trip to get some braided fuel line rated at 350psi was installed and the bike fired right up. Testing will start Saturday but I'm confident that the problem was fixed. Something larger like a fuel pump is $500.

Burst line...

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cpetz24

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I was able to get the pump apart without cutting the fuel line.  It can be done, you just have to be extremely careful.  I'm not bragging, just stating it can be done.  When I did mine I worked on the one way clip that was sandwiched in the back and the hardest to get to.  Got that pried up just enough to make it unclip, then worked the other two up until they also just unclipped, then it was just a matter of working it open enough to get the pump and filter out.  I used like 3 small picks and 3 small flat screwdrivers to get it all pried apart.  Having an extra hand would have been nice, but it is still manageable by yourself.  I promise.  

 

As for the fuel line, it needs to be some pretty stout stuff.  If you think it is nylon, I think they make nylon tubing for tractor trailer brakes.  That stuff should hold the pressure  that the pump builds.  (Not sure exactly what the pressure is, but I thought I heard 40 psi or something) May be something to look for.  

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drtrcr400

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I was able to get the pump apart without cutting the fuel line. It can be done, you just have to be extremely careful. I'm not bragging, just stating it can be done. When I did mine I worked on the one way clip that was sandwiched in the back and the hardest to get to. Got that pried up just enough to make it unclip, then worked the other two up until they also just unclipped, then it was just a matter of working it open enough to get the pump and filter out. I used like 3 small picks and 3 small flat screwdrivers to get it all pried apart. Having an extra hand would have been nice, but it is still manageable by yourself. I promise.

As for the fuel line, it needs to be some pretty stout stuff. If you think it is nylon, I think they make nylon tubing for tractor trailer brakes. That stuff should hold the pressure that the pump builds. (Not sure exactly what the pressure is, but I thought I heard 40 psi or something) May be something to look for.

Just did this, can confirm it's possible. Thanks!
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  • 2 months later...
Grand Master

GHILL28

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Dragging this one back up.  I'm going through my fuel injector and fuel filter today.  Bike got hard to start on the last couple of rides, and the valves still read perfect.

 

Injector cleaning wasn't all that bad.  I now have the fuel pump out and I'm trying to figure out the best way to go about this.

 

1)  Hints for removing the black fuel line and preserving it?  What tools/method?

 

2)  What order to release the one-way tabs?  I see two towards the bottom of the assembly that feel WAY harder to remove than the rest of them.  Are those two necessary?

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drtrcr400

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Dragging this one back up. I'm going through my fuel injector and fuel filter today. Bike got hard to start on the last couple of rides, and the valves still read perfect.

Injector cleaning wasn't all that bad. I now have the fuel pump out and I'm trying to figure out the best way to go about this.

1) Hints for removing the black fuel line and preserving it? What tools/method?

2) What order to release the one-way tabs? I see two towards the bottom of the assembly that feel WAY harder to remove than the rest of them. Are those two necessary?

I did mine a few months ago and it was easier than expected. First off I was able to loosen the pump and remove the filter for cleaning without touching the fuel line. If your careful you'll find there's just enough length to it that you can maneuver things out of the way. As far as getting access to it I pried open the inner most of the the clips first then worked the other two that were easier to access.
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Grand Master

GHILL28

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Okay, finally got this damn thing out and cleaned.  I did it also without having to mess with the fuel line.  That part was not a big deal.  Having to negotiate out those lower 3 tabs was pretty sketchy though.  You basically have to stretch the plastic.  After popping them back and forth a few times, I finally got the outer 2 off first, then negotiated up the inside 1.  I have a feeling this won't happen more than once in the lifetime of a fuel pump.

 

My filter was fairly dirty.  I'm glad I took it apart and got it cleaned up.  I doused it in contact cleaner a few times, ran the ultrasonic with some mineral spirits a couple times, once more with contact cleaner, rinse with with water, blast out generously with air.  I'll see how clean it looks tomorrow.

 

I use tank foam also, but what I saw caught in the filter looked more like dirt.  I suspect that's more from the fuel rather than the tank foam.  

 

60h on the bike in 18 months.

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