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Won't stay between 4500-5100

F
Aug 22, 2012
9
1
3
Hey guys,
Love the passion in this 900 forum. This is my first time posting asking for help. I’ve spent extensive time searching this forum to get answers to solve my problem but I’m at a dead end. I apologize in advance for the long post but I want to be as thorough as possible.
Here is what I have: ’06 900. Bought it out of a barn 2 years ago with 0 miles. Now has 750 miles. All updates done. I’m a nut about doing things right so I’ve done the torque arm, push arm, slp vents, series cooling, balanced primary thru Indy Dan @ 500 miles, he also talked me into the team tied secondary for better backshift (which I love), new fuel filter @ 500 also.
On one trip last year, the machine started to run like crap. Barely got back to the trailer. Would run WOT but not much in between. Check engine light was blinking with absolutely no cadence and thus I could not get a read. After some diagnosis, I saw a dead spot in my TPS and the harness to it was shot. Replaced them both. Runs pretty good now, but not perfect - not the way it should. No check engine light at all now.
The machine will not run smooth between 4500-5100. I don't feel like it's lack of spark. I’ll ease into the throttle, she’ll engage, start to accelerate and I’ll try to cruise at 25 MPH (4800 ish) and at that point, she wants to throw me off. It will wander between 4500-5200 with a steady hold on the throttle. Hammer it and she’s gone without a sputter. I’m guessing you all will say that I’m just driving too slow but I love to ride my 7 year old girls around in an attempt to get them into the sport and we’re constantly slamming helmets.
Would you all be so kind as to give me your thoughts? I don’t think it’s the stator - starts well, idles right down, lights bright at idle, handlebars warm - again very low miles. One thing I did notice - do you all notice a positive or negative pressure inside your gas tank often? Mine seems to have positive pressure many times when I open it. That makes me think that a clogged vent is out of the question. TPS is spot on at .93VDC at idle, 4.28VDC WOT without a hiccup in-between. I don't feel like it will strand me but it pisses me off. Please give me your input :)
 
B

benamen

Active member
Feb 21, 2008
191
25
28
Western Canada
I have had negative pressure in the gas tank due to a kinked vent line after I had pulled the gas tank to replace the ECU. Run the machine with the gas cap loose for a bit to see if it makes a difference?
 
F
Aug 22, 2012
9
1
3
Thanks for the quick reply benamen. I will certainly try the loose cap trick. I feel like the engine goes slightly lean at 4500 and then she tries to correct herself by going rich. No concrete evidence here, just feel.
 
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