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13 kx250f wont idle, dies out shortly after starting

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Buddies 13 KX250F is giving us fits.  It started a month or two ago when the bike started having symptoms of running lean where the idle would hang, then fall off and the bike was hard to start. The bike needs a little bit of throttle input to get it to light up, and it wont stay running no matter where we set the idle speed screw to.

 

The bike had low compression so we tore down the motor. Valves were smoked so picked up new valves, had the seats re-cut, put a set of rings in the motor and rebuilt.  Got it fired up last night and its the same problem. Wont start unless you give it throttle, wont idle, and even when giving it throttle it dies right out after running for only a few seconds when it does fire up.

 

Both injectors were taken out and rigged up to a can of carb cleaner spray and opened and closed with a battery on the workbench. They are both squirting fine with no odd spray patterns or anything that would suggest a clog.  Fuel pressure is good.  All electrical connections are greased and plugged in.

 

 

I am thinking its TPS related since it wont start without throttle input. Does anyone know the stock values for the sensor? I plan on putting 5V to it later tonight and checking the values, but it would be nice to know what I am looking for. 

 

 

Anyone having problems with a brand new low hour 250 starting and running properly?   Its frustrating to my buddy as he purchased the 13 because he was sick of working on his 07 all the time.

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Have you triple checked your valve clearance and timing, including your cam chain tensioner?  It does not sound like a TPS issue.  Double check your filter and air intake track?  

Edited by fivepointnine

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Have you triple checked your valve clearance and timing, including your cam chain tensioner?  It does not sound like a TPS issue.  Double check your filter and air intake track?  

 

Vavle timing and clearance is perfect, cam chain and tensioner are good.  Filter is clean and freshly oiled, intake tract is clean as a whistle.  No air leaks as it does not rev any higher when spraying starting fluid around the airboots.

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I know on my Husaberg FI 450 you cant touch the throttle at all when starting the bike. If the TPS is reading any throttle input the injectors wont fire.  I had thought this was across the board with all manufacturers since Keihn makes all of the throttle bodies and FI systems AFAIK...   Being fuel injected it should start up in 2-3 kicks every time without touching the throttle.

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 I am new to the Kawi game (always been a KTM guy) but with all you have done and checked I would think TPS or another engine monitoring type sensor. 

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Are you sure this isn't as simple as the tip over sensor? And may I ask at how many hours the valves were "smoked"? Seems a little premature for a '13

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Don't forget to check the simple things like bad fuel, good spark plug, etc.

Beyond that I would check the MAP sensor, as the bike uses it for injector and spark timing. The TPS would have to be way out of wack to cause the bike to completely shut off.

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Don't forget to check the simple things like bad fuel, good spark plug, etc.

Beyond that I would check the MAP sensor, as the bike uses it for injector and spark timing. The TPS would have to be way out of wack to cause the bike to completely shut off.

 

 

Good call..  Found the problem before reading this, but it looks like somehow the vaccum line going to the MAP sensor broke.   Interesting that the bike didnt rev up when starting fluid was sprayed near it, but we replaced the hose and all is good.  Starts first kick without throttle input, idles perfect and runs like brand new again!

 

 

Thanks for the replys !

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Good call..  Found the problem before reading this, but it looks like somehow the vaccum line going to the MAP sensor broke.   Interesting that the bike didnt rev up when starting fluid was sprayed near it, but we replaced the hose and all is good.  Starts first kick without throttle input, idles perfect and runs like brand new again!

 

 

Thanks for the replys !

 

Can someone PLEASE tell me where i can find the vacuum line going to the MAP sensor is?

I'm having the exact same problem on my 2013 and can't seem to find what you are talking about.

 

Thanks Tim

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Looking at the parts diagram it is on the left side of the throttle body, right next to the injector.

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Looking at the parts diagram it is on the left side of the throttle body, right next to the injector.

Thanks man, ill take a look. I'm brand new to the whole fuel injection thing.

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Hi I seem to have same problem replaced inlet valves and now it will only start with a bit of throttle and cuts out as soon as u let off no idle wot so ever , does this sound like the vacuum hose to map sensor?

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