mwmx54

2010 yz450 bogs after 15 minutes

30 posts in this topic

It runs fine for 15 minutes, then every once in a while when I open it up, it cuts out, then after 20 min it gets a little worse, and after 45 it barely runs, it cuts out and dies if I twist the throttle more than 5% but then it fires right back up. Here's the weird part, if I turn it off for 3-4 minutes it starts back up and runs fine again for about 10 minutes. I replaced the piston with Oem parts and spark plug about 10 hours ago, it ran fine for about 8 hours and now this. Valves are good, I took the fuel pump apart to where I could see the filter and it looked clean, but there wasn't really much to see, the injector was spotless, as far as I could see. At first I thought it was the air filter because it happened during a moderately dusty race, but I changed it out and it still did it. The gas is new, but when it started happening it had 3 week old gas in it. Maybe that gummed something up. I ran an ounce of seafoam mixed with a gallon of fuel all the way through it then filled it back up and ran it a little more but nothing is helping. Any advice is appreciated before I go spend 450$ on a new fuel pump and injector for the next race in 7 days.

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Sounds like a classic case of a restricted fuel tank vent. Possibly the one way check valve in the vent line is reversed and biased in the wrong direction. If not that, suspect the fuel pump.

When it starts acting up, stop for a second and loosen the gas cap. If that clears the symptoms, it's the vent.

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Sounds like a classic case of a restricted fuel tank vent. Possibly the one way check valve in the vent line is reversed and biased in the wrong direction. If not that, suspect the fuel pump.

Good call!

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Good advice, I never would have thought about the vent line. But, unfortunately the line was clear. I'm gonna order up a new pump and pray that fixes the problem for the race.

And smooth move Yamaha, for being the one manufacturer to not have a replaceable fuel filter.

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Will that be something that needs to be done while its acting up? I blew through the vent line with the cap off the bike but still starched to the line and and it went through fine, only in the one direction through the cap so it seems to all be working.

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make sure that the fuel line has not broken down and is now collapsing in on itself, same thing happened on my bike.

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make sure that the fuel line has not broken down and is now collapsing in on itself, same thing happened on my bike.

the line looks good. and i poured gas through it when i had it apart. i got a pump on the way, just hoping that fixes the problem it could be clogged, i race hare hounds and use a dry break often.

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Good news, plus pics, I have gotten the pump apart and cleaned the filter. wish there was a way to find a replacement filter. anyways, heres some before and after pics. i cleaned it with soap and just filled with soap and water, then blew through the hole and backwashed the filter as much as i could. it was black before, now its white again. im gonna give it a whirl before the race, if it works im gonna send the pump back. if not, ill have a new pump to try. i did have to cut the hose to get it apart, but it shouldnt be hard to find a replacement.

photo-33_zps9415bb65.jpg

cleanphoto-32_zps64c2ac07.jpg

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i got all the part numbers off of this pos made in china pump so im gonna look around and see if i cant find parts to repair them.

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by the way, if anyone else runs into this problem, i was able to remove the filter, as shown in the pics, I had to replace the hose that connects the pump to the filter with a new one, then i cleaned the filter with soap and water, the rinsed it with gas, then reinstalled, I have since then logged well over 400 miles with no problems at all. so if your pump starts givin you problems, try cleaning the filter before you drop 300$ on a new pump.

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Out of curiosity what type of fuel line did you end up replacing the old one with. It sort of looks like the OEM line pictured is of the hard plastic variety you have to heat up to install. I don't have one of the newer FI bikes but i'm sure this question could help someone els out or myself later on down the line.

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8040.00 out the door here today. I stopped of in lunch and checked. Guy was pissed cause he thought it was buying one not just inquiring.

Im guessing they dont sell the filter separately because they want you to replace the pump too and not just for the obvious profit. That pump has a finite life span. You should replace it before it spins for the last time. You dont want to be on the bike on the face of a 90' jump when that thing stops!

Edited by Joe_Jet

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I had the same problem, everything is cleaned and ready to go back together. I do need to replace the hose, does anyone know what I can use in place of the OEM one   

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All automotive fuel systems are like this now. Very few even have external filters.

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I just pulled my pump apart. I was able to do it without cutting the hose. 

Like-wise my filter was black as night. 

I cleaned it but was not able to get as good of results as the OP with cleaning it however.

Here are the pics of it cleaned. I may give it another go cleaning it.

IMG_20140331_203047_026_zpsbmvgbbpx.jpg

 

IMG_20140331_203042_180_zpsg4gqedzp.jpg

 

 

I'm trying to cure an off idle stutter under part throttle and an occasional motor kill when you snap the throttle closed and are downshifting to a quick stop.

It was killing me in the desert during my last USRA race, I swear I had to restart the bike a dozen times.

It always started super easy but would die easy also.

 

Should I be cleaning the fuel injector also?

 

Has anyone run this pump?

 

http://www.highflowfuel.com/i-14472791-new-30mm-intank-efi-fuel-pump-yamaha-yz450f-2010-2014.html

 

and if so have you had good results?

Edited by Gravesdigger

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I just disassembled and cleaned mine - very black as well and lots of crap came out.

 

Couple things I noticed talking it apart if others end up trying this:

 

1. Don't remove the internal hard plastic fuel line, it can be taken apart with it on, just undo the three tabs on the pump housing (I used a pick for the one in the rear and a small screw driver to pry on the other two - in that order)  Then you'll have to undo the filter housing (only one tab) then just pull the whole thing out while bending it towards the hose/pump.  The hose will bend with the assembly and allow the filter and pump to come out as one - just take it slow.  

2.  The filter mounting 'washer' (think washer with small teeth on inside) required some prying on the teeth with a small pick then once a few were bent up, I used a small chisel to pry it off.  Bend the teeth back when you reinstall to make sure it is locked on.

3.  To clean I used a 100% solution of simple green for pressure washers in a small bowl and let it sit for 10 min.  Massage it, and then blow it out with an air compressor.  Rinse and repeat a couple times.  I then dunked it in gasoline and blew it out a couple times just to make sure all the water was out of there.  

 

Haven't had a chance to take it for a good ride yet but it is running well so far.  Hope it cures my issue (intermittent hesitation at low speed when hot).

 

Good luck and don't be afraid to pry pretty hard on the tabs, a few of them required quite a bit of force to release.

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Good luck and don't be afraid to pry pretty hard on the tabs, a few of them required quite a bit of force to release.

...and dont break them!

 

What I read here is, there's no adhesive holding this unit together.  That is, it "snaps" apart via these tabs, and then snaps back together.  Sealing is done via the gaskets apparent in the photos. No adhesive sealers...

 

Do I have that right?  I'm "checking in" from the WR forum to confirm. Thanks!

 

Also, I read no pressure test being performed after the unit is back together.  My .02 is, for safety reasons (since we *are* talking about pressurized gas), consider performing a pressurized leak test: Seal the output, fire up (yah, right) the pump (hook up to a battery), and look for leaks.

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I'm having the same issue on a 11, filter looked really black. My problem is how the hell did you guys get that filter out. I tried and tried but it's so hard to get to with out breaking anything. I will try the tips I read up top, does anyone have a you tube vid on this?? Visual learner lol.

Edited by Dexter42

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