issue with Bike, losing power wierd...

I took my wrr out this afternoon for a nice long ride. 75 degree day.

After riding for about an hr without issue, i pulled over for a quick pit stop, left the bike running.

when I got back on it, and hit the throttle i noticed an odd sputter/shudder with a noticeable power loss. The more throttle I gave it, the worse it got, and the longer I kept going the worse it got. (I'm thinking fuel) After 10 miles of running at 60-55-50, then 45mph, I pulled over and turned the bike off, let it sit for 15 minutes. while it rested, I turned the bike on, and could hear the fuel pump whirring. After letting the bike rest, I got back on it, it started right up, and ran normally for another 20 minutes or so before the symptoms returned.

I recently installed a new IMF 3 gallon tank on Sunday and have put on 60-70 miles on Sunday and Monday before today's ride.

the bike has ran absolutely flawless since I purchased it two years ago.

Am I looking at a fuel pump going out, or could it be something else?

Help!

2008 wr250r
34k miles
FMF
Q4
powerbomb
airbox opened up
AIS removed
all mods done by previous owner.

Fuel tank vent not venting properly?

ToddDubya wrote:

Fuel tank vent not venting properly?

I checked that and I get good flow through the fuel cap.

Sounds like a fuel issue:

Intermittent venting or dirt.

TKO wrote:

Sounds like a fuel issue:

    Intermittent venting or dirt.

I have the pump out and it looks clean. I'm going to change out the pump with a CNT. It's time anyway.

I'll let you all know if that makes a difference.

A few riders presently in South America on WR's. One of them experienced a similar issue on a bike with the late model 'reliable' pump. Sounded similar to your issue. Ultimately he figured it was a spotty connection;
http://advrider.com/index.php?threads/motomavericks-ride-wr250rs-rtw-motos-beer-adventure.1096260/page-19#post-29088578

What does the fuel filter look like?

This isn't a common issue on WRR's but my fi atv is know for plugging up the in tank fuel filter due to a poorly located tank vent, it acts just like what your describing when the filter is dirty/plugged.

If the fuel filter is brown or dirty looking replace it.

pump replaced, bike seems to be running great. I'll do a long ride tomorrow.

Couple of things..

Getting the pump out of the pump housing is a royal pain in the ass. after futzing with it, I went out and bought a set of precision picks and it took no time. Having the right tools makes a difference.

The CNT fuel pump ($30) from Amazon fit great, and came with two spare filters.

two thumbs up.

ride report tomorrow..

no issues on a 150+ mile ride. problem is fixed.