2010 450 problems

Hey guys I have a 2010 yz 450 and this past weekend it started acting up. I cannot diagnose what the problem is. With this new fuel injection I honestly don't have a clue. It is harder to start now, and at about quarter throttle it is really sputtering. Its fine at full throttle /high revs. but at quarter to half it is sputering and backfiring and just running terrible. After you let off the gas it will stall as well. And than it is hard to start. Any ideas?? Its been awesome all year and now this???

thanks Joel C 548

the manual has a lot of info about checking if you have the power tuner you can check most sensors also there is a fault code that can be displayed my friend had a similar problem on a honda it was the air temp sensor

it could also be bad fuel

yep need tuner and check for dtc's! Probably be simple to figure out then.

Did you check to see if you have any intake leaks?

Ya valves are all in spec. dtc's? Also i can check for codes with the yamaha tuner that came with the bike? I guess i should take a look at the manuel.:banana:

mine had a similar problem twice now. both times ive pulled the airbox off, sprayed off the fuel pump, fuel injector, and wipe out the tb very carefully. just remember, when re-assembling, always double check u reconnected all ur sensors! haha i was dumb a lil while ago and did not, didnt start.

Ya valves are all in spec. dtc's? Also i can check for codes with the yamaha tuner that came with the bike? I guess i should take a look at the manuel.:eek:

You need to add a diagnostic tool to the tuner, which is basically an inline wiring harness, and this will allow you to use the tuner for diagnosing errors.

Part number - 90890-03212

:banana:

You need to add a diagnostic tool to the tuner, which is basically an inline wiring harness, and this will allow you to use the tuner for diagnosing errors.

Part number - 90890-03212

:banana:

But you can read dtc's (diagnostic trouble codes) with the tuner and sensor data, I don't see the need for anything else. Is there more than one tuner?

So heres what i've done. Checked valvles, which are good. I've drained all my gas had the air box off and and throttle body. Everything is nice and clean. Unplugged the ECU. I thought maybe this would reset itself. Still the bike is running like junk. My tuner does not bring up any codes and now it will not turn on when plugged in unless the bike is running. If I unplug the condesor than it turns on fine. Soon as the condensor is plugged back it the tuner turns off. Could the condensor be my problem? I think that would make sense for the hard starting issue but would that matter once its running??

had the same issue for about an hour then it stopped totally. try disconnecting the kill switch at the connector under the tank shrouds and see if it fires. If it runs great go buy one at the dealer they run around $32

Have you checked the exhaust for cracks or leaks? My 250f always started backfiring when the exhaust was cracked.

I'm a little lost on the tuner thing? One came with the bike? Does it not show data or codes? Or does it read code 0? List your data engine off and running is you can.

So heres what i've done. Checked valvles, which are good. I've drained all my gas had the air box off and and throttle body. Everything is nice and clean. Unplugged the ECU. I thought maybe this would reset itself. Still the bike is running like junk. My tuner does not bring up any codes and now it will not turn on when plugged in unless the bike is running. If I unplug the condesor than it turns on fine. Soon as the condensor is plugged back it the tuner turns off. Could the condensor be my problem? I think that would make sense for the hard starting issue but would that matter once its running??

it is possible the condenser has failed normaly these types of thing go low resistance and eventerly short circuit this could be a expensive part so try to borrow one and see if this fixes it

After alot of part swapping I have finally diagnosed it to be the tps. My dealer gave me a new bike to swap parts out because I had to race this last weekend. After putting on a new throttle body all my problems disappeared. We than narrowed it down to the tps. So now 250 dollars later I have a new one on order.

thanks for all the help

the condensor was actually my first guess as well but it checked out fine...

After alot of part swapping I have finally diagnosed it to be the tps. My dealer gave me a new bike to swap parts out because I had to race this last weekend. After putting on a new throttle body all my problems disappeared. We than narrowed it down to the tps. So now 250 dollars later I have a new one on order.

thanks for all the help

the condensor was actually my first guess as well but it checked out fine...

Glad you found the problem! Still wondering about your tuner. It doesn't show data?

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