02 WR250 losing power

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6/14/2018 5:26 AM

so i helping my brother troubleshoot his WR250F which keeps losing power. The cold will start up, and run strong for about a minute. Then it will start to bog and baackfire till it slowly loses all power and cuts out. We let it sit for a few minutes and get the same results.

The issue occured after washing it, we have since checked all the electrical connections, replaced the spark plug, and put fresh gas in it.

any suggestions on what to try next. My next thought was to pull the carb off and good through it

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I don't crash, I just run out of talent

6/14/2018 6:01 AM
Edited Date/Time: 6/14/2018 6:01 AM

Fuel cap check valve. Pull off the fuel cap hose and try starting it.

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6/14/2018 6:06 AM
Edited Date/Time: 6/14/2018 6:06 AM

X2 on tank valve, but...
Also check carb vent lines as critters love to live in them. When they are clogged up it stops the fuel flow.

Paw Paw

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6/14/2018 6:07 AM

Id take some electrical contact cleaner and spray it in all the plugs then put dielectric grease on it. I had similar issues on my 450 and it was dirt in the ecu plug. Wouldnt have found it if i didnt do the cleaning/greasing.

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6/14/2018 6:46 AM

Thanks for the advice. When i get home from work, I will take look and clear out all the vent lines, and even try to run it without the cap.

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I don't crash, I just run out of talent

6/14/2018 8:47 AM

NJKawi913 wrote:

Thanks for the advice. When i get home from work, I will take look and clear out all the vent lines, and even try to run it ...more

Just loosen the cap a little is the quick check

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6/14/2018 5:33 PM

So no dice on the tank valve or vent lines. It was running strong for maybe 5 minutes this time before spitting and backfiring. We tested the coil ohms and think that’s may be the source of the problem

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I don't crash, I just run out of talent

6/14/2018 6:24 PM

If the ohm readings on the primary are too low it will allow the coil to break down when it is warmed up and cause lose of spark.
Don't for get to also do an ohms test of the secondary side as a bad plug wire or plug cap can show too high a reading and also cause this issue.
Good luck.

Paw Paw

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