Loses power at or near WOT

[Forbes1964]

A new problem has occurred with my 2009 250 Xciting Ri. Under full acceleration at wot, or when accelerating as if to pass, the engine accelerates normally, then loses power. If I back off for a while and then accelerate normally, it's fine until at or near WOT again. If I hold the throttle, it will gradually lose power  and slow down until it stalls. But if I back off at any time for a few seconds, it will continue to run.

It did it on Tuesday for a while, then it drove normally on Thursday and Friday to and from work (50 miles each way) It drove normally this morning. But now it's doing it again. It acts like its starving for fuel. I don't see an external fuel filter. Nor does the repair manual or owners manual specify a fuel filter interval. The mechanic says that the filter's on the pump. And I removed the fuel pump and checked it. Both  the in tank  filter and tank are clean.

I already changed the spark plug on Monday because it misfired badly on Monday under all conditions . That problem's fixed.
  The pump SEEMS to be pumping great volume and pressure since it overcame the pressure of my thumb over the pump outlet.

What other things besides a weak pump could cause this issue?
Bad injector? Other causes?
If I can't fix it by Monday, I'm taking it to the dealer on Tuesday.. But I'd rather save that money. HELP!!


Sent from my iPad using Tapatalk

[juancuesta]

Defective CDI?

[mclark999]

Did it sit over winter at all? Could need the main jet cleaned

Sent from my SM-G900V using Tapatalk

[Forbes1964]

Did it sit over winter at all? Could need the main jet cleaned

Sent from my SM-G900V using Tapatalk

No. I bought it in January, and it has never sat for more than 3 days since. It's fuel injected, so I'm wondering if the fuel pressure drops under high load conditions. Or maybe the fuel injector is partially clogged.

[Forbes1964]

Defective CDI?

Perhaps. Would a CDI mess up on a sometimes basis? I added some fuel injector cleaner when I refueled last night. After an initial 3 mile drive , sitting for Three hours then being driven moderately for about 20 miles, I drove it at WOT for about a mile, and it did not act up.

I'll drive it again today and see what happens. Hopefully, the injector cleaner did the job. --- intermittent problems are the most frustrating.

[Mr. Paul]

Seafoam is your friend 

[Forbes1964]

Seafoam is your friend 

True. As an auto mechanic, I've witnessed it work wonders in fuel systems and with rings too. They only had STP AT THE convenience store. The only place open at that time. But I'm going to use so me sea foam tomorrow when I refuel. And I'll use it regularly going From there. But as of now, so far, so good.

[Forbes1964]

Seafoam is your friend 

. how often do you use Sea Foam? Every tank or just periodically?
By the way, I drove it to work and back. And it's still working properly. Hopefully the injector cleaner did the trick. Also put sea foam with the current tank of fue
.

[Mr. Paul]

I know some use Seafoam every tank. I just use it occasionally as preventative maintenance. I run a tank through about once a month.

[mclark999]

I bought a scooter that had sat for a long time and I was worried about crud built up in the carb so I've been using Sea Foam each tank. I just took the carb apart to rejet this weekend and it was very clean inside. Going forward, I will probably just use Sea Foam in the winter when I sometimes go a month or more between rides.

Sent from my SM-G900V using Tapatalk