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Discussion Starter #1 (Edited)
Im losing power at a specific RPM? **UPDATE**

Update: Today I finally got into the bike and replaced the fuel pump and made sure none of the lines were pinched. THE PROBLEM STILL EXISTS. I am convinced this is a fuel flow issue but I cannot figure it out. I am holding out as long as possible from taking it to the dealer but this is getting old. Could there be buildup in the lines slowing fuel flow? Anyone with any ideas please share.

ORIGINAL THREAD:

So I did a thread on this a few weeks ago and I thought I fixed it but I guess not.

I will be riding and throttle on, all is normal, then at a specific RPM power will die and the exhaust note will change. It almost sounds like a lawn mower when the choke is on, a little sputtery. It happens in every gear at the same RPM during a single ride. I tried to ride just above the RPM that it starts for example: Power dies at 8500, I will ride at 9000. At a steady throttle it will tug randomly. It feels like power hits for just a second then dies again. It gets weirder... Some rides it wont do anything and pulls through the whole power band just fine, the next ride it will pick on RPM to die at. Sometimes it is 7000, the next ride it will be 11500, Then the next ride it will be fine. It seems almost random. I have ridden several tanks of gas through it like this from different gas companies to see if that helped, no difference. I even ran a couple tanks of "sea foam" cleaner through it, and then in a separate tank tried some octane booster/fuel injector cleaner.

Anyone have any ideas? I am avoiding the dealership at all costs but if I cant figure this out I may have to bend over. I am mechanically inclined and do all my own maintenance but I cannot figure this out. And if I cant figure out the problem I cant fix it. Please tell me its a simple fix and I have been doing something stupid all along.

-No mods have been made to the bike (except cosmetic). No pipe or slip on, no fuel management. Bone stock.
-While at a stand still in neutral or with the clutch pulled in, the bike rev's through all of the RPMs just fine, the exhaust note sounds perfect. The problem is only when I'm rolling.
-Its on 07' with a little over 6500 miles on it
 

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do you have any modifications on your bike? if so what?
 

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Sounds like it's in the range of your secondary injectors kicking in. Maybe the fuel pump can't keep up, or something is damaged within the injectors. Someone should chime in that knows the inner workings better than I do.
 
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Have you done anything with the exhaust valve?

Sounds like it's in the range of your secondary injectors kicking in. Maybe the fuel pump can't keep up, or something is damaged within the injectors. Someone should chime in that knows the inner workings better than I do.
Secondary injectors kick in between 4400RPM and 5000RPM.
 

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Discussion Starter #6
nope she is bone stock, no pipe (or slip on), no fuel management... nothing. Only mods I have made are cosmetic.
 

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That is really odd... i have the exact same problem at 7k. At first i thought it was just because i wasnt used to the 600rr's throttle. But now i def think something is wrong. once in a while ill be cruising in 5th or 6th gear at 7k and it will act like it lost fuel for a second sputters and then right back to normal. Very annoying.
 

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Discussion Starter #11
Fuel pump huh? About how much did that run you? I will try and find some time this weekend to tear it apart and have a look.
 

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I'm having a similar problem. Maybe this will help?
And what would the smaller picture be?

Fuel pump relay obviously works.
Secondary injectors are not the issue as they kick in at 4400-5000 RPM.
Main fuel injectors are not the issue, as even if they were clogged, the secondary injectors would still supply enough fuel to reach redline.
The air filter obviously isn't an issue, since it would not cause RPM's to peak at 9000RPM throughout different gears, as more air would be forced through at higher speeds.
Injector duration/operation wouldn't cause the bike to run fine then stall out at a specific RPM all the time. The odds of that happening are near impossible.

So, that leaves 3 possible causes.
1) A clog or pinch in the fuel line. However, again, for the bike to stall out at a specific RPM with no issues prior to that RPM, not likely.
2) Fuel pressure regulator is bad. Too bad this is a part of the fuel pump unit.
3) Fuel pump is bad.

Timing is advanced by the position of the TPS and CKP, and as there is no O2 sensor on US bikes (aside from CA models) to adjust the ST and LT fuel ratio (a DTC would be set and the MIL would flash if this was a CA bike with an O2 sensor as the LT fuel ratio would have to stay adjusted for too long of a period to correct the ST ratio). With a lower fuel pressure then what the engine needs, enough fuel will not make it's way into the combustion chamber to produce the power needed to continue to accelerate under a load. Incorrect fuel pressure will also stay constant, so that would give the engine a chance of reaching a peak RPM all the time.
Now what happens when the throttle is slightly closed, the ECU retards the ignition timing to accommodate the decrease in air flow. Since the ignition retards, that gives a better chance of complete combustion that produces power with the limited fuel supplied.

There is also the chance that both the TPS and CKP are bad and causing timing to advance too much, but then the knock sensor would detect detonation and would retard the ignition timing while setting a DTC and the MIL turning on.

If I missed anything, I apologise. I don't have a service manual for the 03-06 model to go off of. It really does come in handy at times to be certified by Honda in fuel and emissions system diagnosis/repair.

Edit: It could also be the ICM is damaged, which would mean the ECU needs to be replaced. If the bike will rev up to redline in neutral or with the clutch pulled in, this wont be the issue.
A faulty knock sensor would also cause a problem, but would set a DTC.
Incorrect valve timing (CMP sensor issue) or worn valve springs too could cause a similar issue, but that would just be overall poor performance and not the bike stalling out at 9000RPM. Again, a DTC would be set and the MIL would light.
A faulty speed sensor would cause a problem throughout the entire RPM range.

A stuck open PAIR control valve could be pumping too much exhaust gasses back into the airbox. I'm not sure if this could cause the engine to stall out at a certain RPM, but I highly doubt it.

I think that's everything covered. I hope that is in-depth enough for you and not "sub par". To be honest, what need is there really to explain everything that it could not be when I can just tell the OP what is wrong?
 

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Discussion Starter #14
I'm having a similar problem. Maybe this will help?
I just read your thread. Ya sounds similar. I have a lot of other projects going on right now and I wish I didnt have to deal with this too. So did anyone ever find a place to buy fuel pumps and have an accurate price estimate? I really dont have time right now to fool with the bike so if it doesnt cost too much I might just buy one and replace it regardless.
 

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I just read your thread. Ya sounds similar. I have a lot of other projects going on right now and I wish I didnt have to deal with this too. So did anyone ever find a place to buy fuel pumps and have an accurate price estimate? I really dont have time right now to fool with the bike so if it doesnt cost too much I might just buy one and replace it regardless.
I ebay'd it.. Looks like about $80. But I'll try to find one cheaper and let you know
 

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Fuel pump huh? About how much did that run you? I will try and find some time this weekend to tear it apart and have a look.
thats your fuel pump bro. i had the exact same problem. picked one up from ebay for $35 and it worked like a charm. good luck. :ciao:
 
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