10 450 cutting out


58 replies to this topic
  • moto278

Posted September 24, 2010 - 01:06 PM

#21

well i cant find anything loose or torn or broken. my only guess is that the pump is damaged internally somehow?thinking i should just replace it before another bad accident occurs, or worse

  • fraser

Posted September 25, 2010 - 07:28 AM

#22

I've heard recently of quite a few '10's in the UK that have had kill switches replaced. Apparently they've failed from dirt/washing and I understood they never stopped the bike running, just meant it wouldn't shut off. Might be worth checking, or running it without a kill switch and see if will still fail in the same way?

  • moto278

Posted September 28, 2010 - 03:00 PM

#23

Out at the track right now. With a full tank of gas i did 5 laps no problem. Then goin over a jump it bogged again(checked gas still full). Pulled in looked at filter, clean. Im leaning towards fuel pump right now but wana know what someone else would do before i drop 300 bucks on a new one.

  • brentn

Posted September 28, 2010 - 03:36 PM

#24

Did you disconnect the kill switch?

  • moto278

Posted September 28, 2010 - 03:55 PM

#25

I didnt. Can that cause it to bog down nd not kill?

  • brentn

Posted September 28, 2010 - 04:10 PM

#26

It's been mentioned a couple times...

However if you want to just skip that part and buy a new fuel pump and hope that's the issue, go ahead :smirk:

  • moto278

Posted September 28, 2010 - 04:21 PM

#27

Lol ill try disconnecting it next time and see what happens. Bike just scares the s*it out of me while riding with it acting this way. This weekend i am gona strip it down and clean the throttle body and intake tract. Just to be safe

  • tech24

Posted September 29, 2010 - 03:50 AM

#28

Sure sounds like a fuel pump deal, gonna have to guess no matter what with this type of problem unless you want to hook up a fuel pressure guage and attach it to bar pad and watch it when it happens.

  • kx450f63

Posted September 29, 2010 - 04:02 AM

#29

You need to treat these new FI scooters just like a car when diagnosing run-ability problems. Put the fuel pressure gauge on it and test. Do your research, start with the most likely and work your way around.

  • tech24

Posted September 29, 2010 - 07:06 AM

#30

you can test fuel pressure all you want and it wont tell you crap unless you watch it while the problem occurs

Have you checked for trouble codes by any chance, I just read back through the thread and didn't see anything mentioned?

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  • moto278

Posted September 29, 2010 - 08:45 AM

#31

I did pull it up. Nothin showed up. A friend who is big into crotch rockets suggested the mapping. I have a full pc system and run u4.2 and 4.4 and twin air filter with the jay marmount map. He said he had a power commander on an older cbr nd he tuned it but ran similar to my yz so he went back to stock. Another thing. Last night at the track after it bogged down i just went around the short track in the same area. No problemss at all with it and i went in circles for almost an hour

  • tech24

Posted September 29, 2010 - 08:52 AM

#32

I guess mapping is possible but you would have to get really aggressive with the GYTR tuner to casue a drivability problem due to the limited amount of adjustable fuel cells. It would be worth a try to return to stock.

  • brentn

Posted September 29, 2010 - 10:01 AM

#33

No matter how much you dicked around with the tuner, you will not cause the engine to just die out.
His issue is when he lands jumps, so sudden violent movements with the bike. It's mechanical or it's electrical.

He should check the kill switch because he can rule that out easily by just disconnecting it. If that's not it, then he can approach the pump which is more involved.

  • tech24

Posted September 29, 2010 - 10:13 AM

#34

No matter how much you dicked around with the tuner, you will not cause the engine to just die out.
His issue is when he lands jumps, so sudden violent movements with the bike. It's mechanical or it's electrical.

He should check the kill switch because he can rule that out easily by just disconnecting it. If that's not it, then he can approach the pump which is more involved.


I was refering more to the bogging but yeah your right

  • moto278

Posted September 29, 2010 - 01:26 PM

#35

loving the discussion! i have the kill switch disconnected now. gona inspect the throttlebody and intake tract tonight/tomoro. and will be doin some ridin friday to see how it goes. if it bogs again, ill return to stock. and see wat happens from there

  • kx450f63

Posted September 30, 2010 - 04:03 AM

#36

you can test fuel pressure all you want and it wont tell you crap unless you watch it while the problem occurs

Have you checked for trouble codes by any chance, I just read back through the thread and didn't see anything mentioned?


In case you didn't realize, I was agreeing with you, but since you snapped, here goes... If an injector poppet is designed to be lifted off it's seat with 8 PSI at idle and you only have 6 PSI would you consider that a problem even though the bike idles fine? You now have 25% less fuel PSI than designed and certainly this could indicate a problem.

Back to your problem at hand moto278. Diagnosing this type of problem is certainly a pay attention to detail process. I think the kill switch is highly unlikely but it is easy to find out. The mapping is also highly unlikely but also easy to find out. (did it ever run properly with the mods?) With the info given so far it sounds to me like it is something that is vibration and or heat related, which I know doesn't rule out very much. If it were me I would start where you are by finding out by all means necessary who else had this type of problem, how they diagnosed it, and what the fix was in their case. If nobody gives you any good info. then start with the visual inspection of everything including a hand held diagnostic tool then go from there. If nothing shows up my next stop would be the electrical supply system ohm test (cold compared to hot) and the fuel pump test.

  • tech24

Posted September 30, 2010 - 04:17 AM

#37

In case you didn't realize, I was agreeing with you, but since you snapped, here goes... If an injector poppet is designed to be lifted off it's seat with 8 PSI at idle and you only have 6 PSI would you consider that a problem even though the bike idles fine? You now have 25% less fuel PSI than designed and certainly this could indicate a problem.

Back to your problem at hand moto278. Diagnosing this type of problem is certainly a pay attention to detail process. I think the kill switch is highly unlikely but it is easy to find out. The mapping is also highly unlikely but also easy to find out. (did it ever run properly with the mods?) With the info given so far it sounds to me like it is something that is vibration and or heat related, which I know doesn't rule out very much. If it were me I would start where you are by finding out by all means necessary who else had this type of problem, how they diagnosed it, and what the fix was in their case. If nobody gives you any good info. then start with the visual inspection of everything including a hand held diagnostic tool then go from there. If nothing shows up my next stop would be the electrical supply system ohm test (cold compared to hot) and the fuel pump test.


I didn't mean it to come across that way :smirk: Just saying its probably a waste of time but worth doing none the less and could show something.

  • tech24

Posted September 30, 2010 - 05:19 AM

#38

and not to be an ass but on an electronic fuel injector the fuel pressure holds the valve and pintle closed but I think you were just using a general description to make a point and I agree a fuel pressure reading should be taken and if an inline adapter is available then it can be ridden with guage hooked up.

  • kx450f63

Posted October 01, 2010 - 03:24 AM

#39

Now that we got that out of the way and I understand you have at least basic knowledge of what you are talking about, your correct in thinking I was making a general statement as this is not the place we need to get into engineering details.

As of rite now I don't even know what the fuel psi should be on a 2k10 kx450f. I just bought my first 2k11 kx450f two days ago and have not gotten a service manual yet. At first glance the fuel line connectors look like the old school bosch connectors which tells me it should be low psi.

As I am typing this I am reminded of a recent problem involving fuel caps. I have had personal experience with the inside of the cap failing to the point it will cause a vacuum in the tank just like the check valves in the vent hose do when they fail. I never did take the time to figure out why or how. I am sure it was the cap because I removed the check valve from the vent hose and still had the same problem. Replaced the cap and the problem disappeared. I bought one of those cool looking vent hose free No-Toil fuel caps for my 08 and loved it for about a year, then it did the same thing. They replaced it for me and all was well again. I checked last night to see if it would fit on my 2k11 and it does. I rode for about 10 minuets and the thing stalled a couple times in turns and I was thinking, ya rite this fi stuff is no better than my carb. Then I released the fuel cap and sure enough the infamous rush of air sound when I released it. Either the cap doesn't fit properly or the check valve failed on it just like the last one. I am going to call the manufacture today to inquire. So just a reminder, check the fuel cap.

  • tech24

Posted October 01, 2010 - 04:59 AM

#40

It would be nice if it was a simple as a cap that would be easily overlooked. Be a cheap fix and something to check. I don't know what fuel pressure is on 2010 yz I have the manual but haven't looked.





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