(PACIFICBUSA @ Sep. 14 2007,17:40) Hokay....there's three things you may want to check. I won't say to not get another pump...that's a piece that you would not mind having a spare. FWIW, I have a 99, so the fuel system is the same. Actually, the bikes are more or less the same...mechanically, of course. Again, these are things that you may want to check:
First off, check your kickstand. After awhile, the spring may get worn. If you haven't replaced the original spring, it may be time to do so. If you look carefully at your kickstand assy, you'll see a button of sorts that is pressed in when the kickstand is up. Under hard acceleration and at certain RPMS, the vibrations from the engine may actually rattle the kickstand just a bit, which in turn relieves the pressure on the switch. That causes what feels like bogging or stalling. Give it a couple of runs...if it consistently stalls or bogs at that RPM, then double-check your kickstand assy. One easy way to do it is to put it in first, grab the front brake tightly, put your RPMS in the 3-4500 range and slowly release the clutch to the grab point. When the clutch is at the grab point, start to release the front brake. Not to much where you're going to launch, but just enough to keep the engine from stalling out. If you notice some stalling, then it'll be a good idea to look at your kickstand assy and see if your kickstand is slowly being vibrated down. It won't come all the way down, but the shift from it's original placement will be noticeable. Pay close attention to it...if you notice your engine cutting out, then you've found out why you're getting those somewhat disconcerting stalls at the middle of the rev range.
Another thing to check is your fuel delivery sytem. That covers everytihng from your supply and return lines running from your petcock to your fuel pump assy. Get your plugs from your undertray (they'll be at the back and on the brake side) and plug your petcock. Remove the lines and check for cracks or leaks. Be sure to put some pressure through them, as the cracks may not be noticeable when the hoses are not stressed.
Staying with your fuel delivery system, the next item to check is the fuel pump assy. Now the reason why you didn't see the fuel filter is because it is located in the actual fuel pump housing. When you remove your fuel pump housing, you are going to see that the assembly is actually made up of two parts, the upper and the lower. In the lower sits your fuel pump; in the upper sits your filter. Now the filter itself is made up of a crummy paper...it is a possibility that after so many years, the filter may have deteriorated and is therefore not only hindering your fuel delivery, but possibly clogging up your fuel rail....or even worse, it may have gotten to your injectors. Be gentle when you're taking apart your fuel pump housing...and be patient. Doing it right is going to be a practice of both. Don't muscle it...when you start muscling stuff around here, things end up getting broken pretty quickly. And this is a pretty damned bad place to be having stuff break. You're gonna need to disassemble the housing and pull out the pump. It's going to be tough, but take your time with it and DO NOT force it...things get bent out of shape real easy, and that's not a good thing. There's going to be a plastic sleeve around your pump...you're gonna need to pull at that firmly but gently. When you get it out, examine that plastic sleeve...there's a screen on the bottom. Make sure that's clear and free of gunk. Also pay attention to the bottom part of the lower pump housing...there's another screen there that you need to make sure is clear of gunk and stuff. Don't be too hard with it, though...you may end up popping the screen out of place, and may God be with you if you end up doing that. It's gonna be a you-know-what to get that error corrected.
After you get that cleared up (if you need to do so), it's time to tackle the upper part of the housing assembly. After you remove that plastic piece, you'll come across your elusive fuel filter. It won't hurt to get it changed out...in fact, if it hasn't been replaced, it's a good idea to do so. Also be sure to get some new o-rings...you're gonna need to replace those as well, unless you're got the touch of a feather. The o-rings are gonna be stretched and bent out of shape by the time you wrestle that plastic piece out.
Ok...I know this has been long, but stay with me on this, ok?
Then next item to check on will be your fuel rail and the screens on the injector. Again, you're gonna need to be gentle here. This is NOT a part you want to mess up...if you do, things are gonna be running pretty rough afterwards if you do. In fact, it may be easier to just buy some new injector screens and it certainly wouldn't hurt to get yourself some new injectors as well. Unless the engine has been worked on, it's a good time to replace these.
Now if all these things are in good shape, then you need to check the relating items in your fuel delivery system. Check for any dead plugs (yes, some of them can be duds right out of the box) and you may also want to check your spark plug rubber thingys. Those are the things you need to remove to get to the spark plug. I can't remember what they were called, so I guess "thingy" will have to do for now.
If those check out ot be ok, then it's time to check your vaccum hoses...make sure that they aren't cracked. Also be sure to check your air sensor hose...you'll find that on the air box facing the engine, right in the middle part. You'll know it's the right one by looking at the airbox and locating the hoses that are nestled in between the two bulges in the airbox, facing the engine. Make sure that those hoses are not cracked or out of place.
So...if you have time, check on all those things over the weekend. If that didn't work, then it's on to a lengthier process of elimination. I'm hoping that the remedy is simple...and not costly. I'll check in a little later, so if things didn't work out, be sure to PM me and we'll take it from there.
In the meantime, get to work...and let me know if what I said was helpful or if it was just full of sh*t.
