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Discussion Starter #1
So I've spent the last three weeks hating life because my 03 636 has been bogging out past 7000 RPM. Seeing that I have some troubleshooting skills i thought i had gone down every avenue and read every thread on the subject.:O

As it turned out, while i had narrowed it down to fuel i never thought of the answer until i came across this thread: http://zx6r.com/zx6r/8339-gas-venting-problem-kream-coating.html

I had always heard the whistling when i first bought the bike but and understood the concept of venting in the tank. What i didn't notice through the winter was that the whistling had stopped and, just as spring arrived and the weather got warm, the bike started running like crap.

Currentlty I have the bike fuel system disassembled down to the injectors for cleaning, so tomorrow i'll have it all back together again plus a cleaned out fuel cap. Hopefully with a positive update.
 

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Did you spray out the fuel filter?

Not the pump, but actually disassembled the pump and got to the fuel filter?

Edit: I ask because this is actually a semi-notorious problem on that year of bike. Mine did the same thing and it turned out that I needed to pull apart the fuel pump, and spray out the fuel filter.
 

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Discussion Starter #3
Read a post on that a day or two ago, but couldn't find anything on disassembling pump. I tried doing it myself but didn't get much farther than removing electrical leads.

Any suggestions?
 

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after you clean the injectors i would run some seafom with some good gas threw the tank to see if that fix the problem.
 

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Discussion Starter #5
OK Fuel system is back in place and aboout to head for a ride with seafoam in the tank.

Will post results.
 

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Discussion Starter #6
Ran it last night, with all parts reassembled. Bike still had acceleration issues despite fuel cap being open. Which rules out a tank vent problem. Back to the drawing board.

Next trail and error will be checking reeds under the caps on the valve cover and trying to pull the fuel pump apart again.
 

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check fuel pressure. Like, go borrow/buy the gauge, and actually hook it up.

Also, how many miles are on the bike and when were the valve clearances last checked?

You say you've narrowed it down to fuel, but how did that process take place? why are you so convinced that the issue is fueling, not air or ignition or timing or compression? Does the symptom present itself in all gears at all throttle positions with various engine loads?
 

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Discussion Starter #8
check fuel pressure. Like, go borrow/buy the gauge, and actually hook it up.

Also, how many miles are on the bike and when were the valve clearances last checked?

You say you've narrowed it down to fuel, but how did that process take place? why are you so convinced that the issue is fueling, not air or ignition or timing or compression? Does the symptom present itself in all gears at all throttle positions with various engine loads?
Zoom, my bike just passed the 25k mark recently.

Trouble shooting methodology.
Air - Systematically removed all filters and restriction from the intake to finally removing the airbox. I then ran the bike without the air box and visually checked to make sure, both the primary and secondary butterflies were functioning correctly. Secondaries completed function check as normal when igniton was on. Primaries opened and closed smoothly with throttle. Also checked resistance across TPS's. All checked out. And while running the engine still bogged out with no air restriction.

Spark - Checked resistance on all coils and performed spark test by grounding out exposed plugs (also replaced spark plugs with brand new NGK iridiums). Made assumption the ECU was timing them correctly because it idled fine, and increased revs smoothly up to approx 7500 RPM's

Fuel - Started by removing fuel pump. Unfortunately i was afraid i'd break it when i couldn't figure out how to take it apart so i did a visual check and ran the required voltage to the leads (used a variable power supply from where i work). Pump turned on as it should. I didn't have the gear to check the output pressure, so i put it back in the tank. I then pulled apart and cleaned out the fuel rail and injectors. I the tested the resistance across each injector, and once again hooked them up to the power supply to make sure the were functiong. Each one clicked as they were supposed to. Once i put the fuel rail back on the throttle body. I thought about checking the valves but my repair experience hasn't taken me that far yet (loosely translated " I don't know how to do that"). So i racked my brain and read some threads and decided to reviisit the fuel pump, it made the most sense that restriction there would allow enough fuel to push the revs to 7500, but no further. Kinda like beefing up a muscle car without increasing the size of the injectors.

BTW i'm new to this whole forum thing (13 posts and counting) wasn't sure i needed to add all this info. But i will from now on.

Thanks for the help.
 

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Discussion Starter #9
Oh yeah, I almost forgot...

I took the fuel pump apart and found that the filter was seriously clogged. I tried to clean it out, but i ended up shifting the sediment and clogged it even more. Max revs went from 7500 to 3000. So I took the pump apart again and removed the filter completely. My bike runs like a champ again!:)

Only problem is that by removing the filter i was leaving my injection system exposed. So i fabricated an in-line filter which seems to be doing OK so far. Bike starts kinda rough now but once it warms up it does great.

The fabricated filter will work for now but i will be buying a new pump ( and new fuel line soon).

For those that need help with breaking down the fuel pump i will start a new thread with pics and instructions.

Thanks for all of your help.
 

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Discussion Starter #10
I know it's been awhile since any updates on the issue but, about 3 weeks after the last post I ordered a new pump, everything 's back to normal. WHich was a very good thing because the same day it arrived. The old one quit. My guess is it had foreign debri in it, seized, and then smoked itself. Been runnig great ever since.
 
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