2014 WR250R hard starting when warm

Hello, all,

I'm new here and couldn't find the answer to this question for this year 250.

My 2014 starts great when cold. But after it warms up, even for a bit, its hard to start. Matter of fact, I have to hold the throttle open 1/8 turn for it to start then slowly decrease it. The RPM stay very low then after about 1 minute it idles as normal, around 1500 rpm.

The only mods are the fmf Q4, AIS delete, Exhaust servo delete, and airbox mod.

The fuel pump, which is discussed on many 2008 models, seems ok. I here is prime every time I turn on the key.

I've installed and removed the FMF programmer and I have the same results.

I've messed with the CO setting. Currently I'm at -1. It doesnt matter where I put it, same results.

I've also messed with the air bypass screw. No results.

I've installed a new plug and new air filter, no results.

Any ideas? Or a link to thread that discusses this.

Thank you all!!!

I did remove the FMF programer. No big results.

I inspected the plug. RICH.

Could it be the air intake pressure sensor?

Dont know for sure, but it makes sence, meassure it.
Theres also a coolant temperature senser that does "something" so meassure that according to the manual aswell.

How many miles on it? If youre able to do the work yourself I'd check valve clearences aswell, just to rule the out.

Thanks for the response. I fixed it yesterday. The bike has 5500 miles.

Yes, I did checked the valves and even messed with the cam chain tensioner to see if I can get the cams and the stator TDC mark to line up. They will never line up perfect. It's off a 1/2 tooth but that is normal.

So after many many hours of checking and testing sensors relating the the fuel injection, i removed the vacuum hose to the throttle body pressure sensor. Shoot, it ran so well. I reconnected that vacuum line and then discovered that the other vacuum line that 'was' connected to the airbox flapper was connected incorrectly to the fuel tank vent. That said, it was creating a vacuum on the tank.

I solved that problem but it was still running a little weird. I then clean, with carb. cleaner, the air bypass screw, AKA idle adjustment. While I was doing that i disconnected the leads off the battery and then connected the negative lead to the positive lead in effort to 'hard reset' the computer.

Alas, it runs so well. I can't believe it. Just like new. Only took me about 15hrs to diagnose. It was worth it. Zero dollars spent and I got a killer deal on the machine.

Best of luck out there!

Thank you for coming back to post the findings.

Well done!

Could you lay your hands on mine?