YZ250 Problems ANY HELP???

denyz250f
Hello there everyone,

I have a yz250f 2016 fuel injection 4 stroke motocross bike, the bike is driving me insane as i have an issue with it.

The problem is, one minute the bike will start up and rev no problem at all will run great for as long as you keep it running, you then turn the bike off and it won't take a rev, will just bog out and back fire, after a lot off attempts of turning it of and starting it back up again you might get it to run sweet again, I have replaced the injector, had a full top end rebuild done and also sent the stator off for testing, Bike is still the same, i am reading a lot off people saying about TPS and wiring harnesses,

Could anyone point me in the right direction as it is an intermittent Fault,

How do i Check the TPS Sensor?

Any help would be much appreciated.

Many Thanks
Dennis
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Wade221
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Wade221 2/15/2020 2:40pm
2/15/2020 2:40pm
Dirtydeeds wrote:
What color power band you runnin?
Two purples! Grip it, and rip it ✊🏻
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2F4A
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2F4A 2/16/2020 8:17am
2/16/2020 8:17am
Check the connector on the injector. Clean it and check if there is no damage at the wiring. Had simmilair problems on my KTM which was a simple connector issue
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Wolfey
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Wolfey 2/16/2020 8:25am
2/16/2020 8:25am
I had the exact same bike with the exact same issues. I replaced the air pressure sensor and never had the problem again. Also try disconnecting the kill switch. They have been known to cause similar issues from water getting inside.
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Talisker
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Talisker 2/16/2020 8:25am
2/16/2020 8:25am
Make sure the fuel line is not twisted or pinched while re-installing the gas tank. Sounds simple, but it’s real easy to do. If not you may have a clogged fuel injector. Had this problem on a 13 YZ450. Would not rev past a certain rpm. You can send it in to have someone clean it or try a Motion Pro injector cleaner.
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denyz250f 2/17/2020 11:38am
2/17/2020 11:38am
Wolfey wrote:
I had the exact same bike with the exact same issues. I replaced the air pressure sensor and never had the problem again. Also try disconnecting...
I had the exact same bike with the exact same issues. I replaced the air pressure sensor and never had the problem again. Also try disconnecting the kill switch. They have been known to cause similar issues from water getting inside.
Thanks for the reply, i will try this as i have checked just about everything else. cheers.
denyz250f 2/17/2020 11:39am
2/17/2020 11:39am
foreman52 wrote:
Valves?
its had a full top end rebuild, no expense spared and still the same issue's, i would be as well to burn my money, save the hassle ha ha.
denyz250f 2/17/2020 11:41am
2/17/2020 11:41am
Talisker wrote:
Make sure the fuel line is not twisted or pinched while re-installing the gas tank. Sounds simple, but it’s real easy to do. If not you...
Make sure the fuel line is not twisted or pinched while re-installing the gas tank. Sounds simple, but it’s real easy to do. If not you may have a clogged fuel injector. Had this problem on a 13 YZ450. Would not rev past a certain rpm. You can send it in to have someone clean it or try a Motion Pro injector cleaner.
I check all this and its still the same, i also replace the injector as that was my first thought with the bike.
denyz250f 2/17/2020 11:42am
2/17/2020 11:42am
2F4A wrote:
Check the connector on the injector. Clean it and check if there is no damage at the wiring. Had simmilair problems on my KTM which was...
Check the connector on the injector. Clean it and check if there is no damage at the wiring. Had simmilair problems on my KTM which was a simple connector issue
Hi i will check this, and let you know how i get one, reading alot of reviews with people saying to check the TPS and the air pressure sensor.
Wade221
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Wade221 2/17/2020 11:48am
2/17/2020 11:48am
denyz250f wrote:
I check all this and its still the same, i also replace the injector as that was my first thought with the bike.
Had a buddy with similar issues with his YZ. Culprit was moisture in electrical connections. Blowout with air, and pack with dialectic grease before reconnecting and see if that remedies 🤷🏻‍♂️
denyz250f 2/17/2020 12:34pm
2/17/2020 12:34pm
denyz250f wrote:
I check all this and its still the same, i also replace the injector as that was my first thought with the bike.
Wade221 wrote:
Had a buddy with similar issues with his YZ. Culprit was moisture in electrical connections. Blowout with air, and pack with dialectic grease before reconnecting and...
Had a buddy with similar issues with his YZ. Culprit was moisture in electrical connections. Blowout with air, and pack with dialectic grease before reconnecting and see if that remedies 🤷🏻‍♂️
i will try this and let you know how i get on, thanks for the reply.
Caseclosed713 2/17/2020 1:25pm
2/17/2020 1:25pm Edited Date/Time 2/17/2020 1:33pm
Intermittent electrical issues suck. I had something sort of similar happen with a KTM I owned. Sometimes after washing it, it would randomly act up and misfire. I blew out every connector and put dielectric grease in it before putting back together.

Working in a bike shop for years I have seen bad grounds, bad spark plug caps with too much resistance or arcing to the head, and wires shorting to ground also cause those kinds of issues.
sgrimmxdad
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sgrimmxdad 2/17/2020 2:54pm
2/17/2020 2:54pm
The dealership is your best bet for checking the TPS. It does sound a lot like an electrical problem. The 14&15 had the bad TPS, 16 has the updated part. Still doesn't mean it didn't get knocked around during your rebuild and the position moved. You can try loosening the bolts on the TPS and moving it ever so slightly back and forth to see if that helps.
CR250Rider
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CR250Rider 2/17/2020 2:59pm
2/17/2020 2:59pm Edited Date/Time 2/17/2020 2:59pm
1 click up on the needle, you're too rich
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