2015 yz250f only runs with choke on

Christian_Hannemann
Edited Date/Time 12/9/2015 11:02am
I have a 2015 yz250f that has about 30 hours on it. When the problem orginaly happened I could not kick start it at all only bump start with the choke on. As soon as I get going with the choke on it runs fine but as soon as I shut the choke off it dies.

I checked my valves and my intake side was tight so I shimmed them and now it will kick start but still only runs with the choke on. As soon as I shut it of it dies. I cleaned the throttle body and there was some dirt in there also.

Could the injectors be clogged at all? I did not have a security torques to take the injectors off. So I did not clean them. Open to any suggestions thank you!! (I also understand it's a high idle just calling it a choke cuz it's easier)
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Paw Paw 271
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Paw Paw 271 9/21/2015 5:20pm
9/21/2015 5:20pm Edited Date/Time 9/21/2015 5:23pm
Sounds like it could be a TPS sensor issue. You see the TPS controls the fuel mix at all stages of the rpms, but if not set correctly it will not idle or start easy. This sensor uses very low voltage to tell the ECM how much fuel to send. The lower the voltage the lower the fuel quantity. The higher the voltage the higher the fuel quantity. The service manual will tell you how to check it and what the correct setting for the TPS should be.

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Christian_Hannemann 9/21/2015 6:58pm
9/21/2015 6:58pm
Thanks paw paw! I will definitely try that. I was thinking about draining the gas and cleaning that too because there was an awful lot of dirt in the throttle body.
Paw Paw 271
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Paw Paw 271 9/21/2015 7:08pm
9/21/2015 7:08pm
Why so much dirt in the throttle body? Air filter failure? Poor sealing at the intake?

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slackinoff
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slackinoff 9/22/2015 7:03am
9/22/2015 7:03am
With the choke on, spin the choke knob one way to raise the idle a bit, then take the choke off and see what happens.
The idle speed might be out of wack is all (too low). Turning the choke knob is how you raise it.

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m121c
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m121c 9/22/2015 10:09am
9/22/2015 10:09am
No water issues when washing the bike? I had an issue from the manufacturer that destroyed my top end. The fuel injector O-Ring was crushed when they installed it and it was sucking air/dirt/water/etc. directly into the throttle body.

Weird you had a substantial amount of dirt in the throttle body.

Yamaha definitely has a rep for having a bad TPS, if you read this topic: http://m.vitalmx.com/forums/Race-Shop,42/2015-YZ250F-PROBLEMS,1285291?p…. The last page is probably the most notable, posts from actual Yamaha tech's.

There is a new TPS for these bikes... I was told there was not by Rock River, but the part numbers do not lie.

1SL-85885-00-00 - OLD
1SL-85885-01-00 - NEW

If you go to page 3 sgrimmxdad explains that he had to get the new one for his sons bike.

Hopefully you find your issue quickly, mine took 3 months and was a fight from the start with Yamaha.
Christian_Hannemann 9/22/2015 10:36am
9/22/2015 10:36am
I found a hole in the bottom of my air filter where it seals so I'm assuming that that is where the dirt got into the throttle body. And m121c it did start out with when I would wash it it wouldnt start. Then I would bump start it and it was fine. Then the next time I went to ride it didn't even want to start at all and would only run with the choke on.

I just put a brand new air filter in and bought a couple extras for spares. And I was going to tear the top end apart and see if everything is okay and I wanted to check the injectors also.
Mx231
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Mx231 12/6/2015 9:20pm
12/6/2015 9:20pm
I am also having the issue of my 2014 not running without the choke. Did you try changing the TPS sensor?
pete24
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pete24 12/7/2015 6:16am
12/7/2015 6:16am
this mite sound dum but did you try turing the idle up? everytime i pulled the choke on my 13 yz 450 i musta turned the idle a click or two and i would have to readjust it once a month
Mx231
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Mx231 12/7/2015 1:23pm
12/7/2015 1:23pm
Mr. Robinson wrote:
Your pilot jet is plugged.
Thanks I will look into it.
BobPA
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BobPA 12/8/2015 5:06pm
12/8/2015 5:06pm
Mr. Robinson wrote:
Your pilot jet is plugged.
Mx231 wrote:
Thanks I will look into it.
Good luck....
RyanLester761
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RyanLester761 12/8/2015 5:28pm
12/8/2015 5:28pm
Mr. Robinson wrote:
Your pilot jet is plugged.
Mx231 wrote:
Thanks I will look into it.
BobPA wrote:
Good luck....
I'm not an expert but I don't believe a fuel injected bike has a pilot jet. Haha.
Mx231
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Mx231 12/8/2015 5:31pm
12/8/2015 5:31pm
Mx231 wrote:
Thanks I will look into it.
BobPA wrote:
Good luck....
RyanLester761 wrote:
I'm not an expert but I don't believe a fuel injected bike has a pilot jet. Haha.
Ya I figured that out but read to try amsoil quickshot to help clean everything out
Mr. Robinson 12/9/2015 12:00am
12/9/2015 12:00am
Mx231 wrote:
Thanks I will look into it.
BobPA wrote:
Good luck....
RyanLester761 wrote:
I'm not an expert but I don't believe a fuel injected bike has a pilot jet. Haha.
My bad. I thought it said 2005. Sorry.
sgrimmxdad
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sgrimmxdad 12/9/2015 6:42am
12/9/2015 6:42am
Has anyone turned the choke/idle knob? Can you turn up the idle and keep it running?
davbrucas
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davbrucas 12/9/2015 8:21am
12/9/2015 8:21am
All the choke does is restrict airflow to enrichen the mixture for starting. You can try to clean the injector and draining the tank and using fresh fuel first. If that does not help, get the GYTR tuner and check for trouble codes. This will lead you to your problem. I have read about TPS issues as well as faulty injectors.
Mx231
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Mx231 12/9/2015 8:29am
12/9/2015 8:29am
davbrucas wrote:
All the choke does is restrict airflow to enrichen the mixture for starting. You can try to clean the injector and draining the tank and using...
All the choke does is restrict airflow to enrichen the mixture for starting. You can try to clean the injector and draining the tank and using fresh fuel first. If that does not help, get the GYTR tuner and check for trouble codes. This will lead you to your problem. I have read about TPS issues as well as faulty injectors.
Thanks for the suggestions, I haven't been able to look at it since I'm at college but plan on looking into it over winter break
Christian_Hannemann 12/9/2015 11:02am
12/9/2015 11:02am
Hi sorry haven't posted for a while. What I did was I tested all the tps sensor the air intake temperature everything with my multi meter and it all was in spec. I decided to clean everything I cleaned the injectors the throttle body washed the gas out of the gas tank everything. So I went out and bought a gytr tuner and when I was checking everything out I found out that my tps sensor was set wrong. If you don't have it at the right angle it will make your bike run funky. So I set that to spec and that seemed to clear the problem right up for me. Keep in mind that when you test the tps sensor it can test that it's good but if it is set to the wrong angle it will not work properly. Thanks for all the segestions!
mx724
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mx724 6/16/2016 4:31am
6/16/2016 4:31am
How did you test this when using the multi meter? Im not having the issue but i didnt see a clear order of operation in the manual? Also do they provide the angle to be set at? Juat looking for a bit more info as I may by a spare in anticipation

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