Still can't get the darn thing to run right...

[shortymac83]

Ok, I have 2 questions. 2003 Buell xb9r, all stock, as far as I can tell.

1. The bike has an intermittent stutter that happens randomly and appears out of nowhere. If it is at speed, the motor gets choppy and loud (almost like it's missing on a cylinder) and lose nearly all power. Floored doesn't accelerate it much, then will smooth out after a few seconds of this. If it happens to do it while decelerating to a stop, if you come to a complete stop, it'll usually continue to idle, but as soon as you go to accelerate, it chuffs and dies. Further, while at constant speed, you can feel power surging, even though it feels like it's running "right" (i.e. no choppiness, etc). It also likes to do that chuffy sneezy backfire thing that apparently sportsters are known to do. It doesn't ever throw a check engine light, nor did it store any codes when I ran the computer during the TPS reset.

Things I've checked:

A. assuming it was an electrical issue, I checked all obvious grounds as well as battery connections. I deleted both the clutch and kickstand safety switches.

B. I reset the TPS

C. Pulled and checked the fuel pump and associated wires.

D. New plugs

It had sat for a while, so I ran both Seafoam and MMO through it (not on the same tank). I'm assuming that since it's an intermittent problem, it isn't a constant issue, like gunky injectors or leaky intake gaskets or something, but I'm thinking that's my next stop. How does one go about checking coil strength?

2. The belt tensioner is stuck onto the mounting bolts. Normally I wouldn't really sweat it, but the muffler is starting to look rather rotten. How do I get this damn thing off the corroded bolts?

 

[Cooter]

Man I would have guessed #C right away. When you pulled the pump, was the sock full of junk? The pump could still be on it's way out. Is it loud?

Or a coil wire arcing/ routed wrong, or coil with a bad ground/mounting bolt.

 

[shortymac83]

No, the sock was pretty clean (actually, from what I could see, there weren't any goobers in the tank or on the pump). It does have the original pump, and it will occasionally howl, like it does at startup, but that isn't when the issue happens.

As for the coil, I'm going to have to check my fsm, but I'm only seeing one box that the plug wires attach to. Is that it, or is there more than one separate coil? It is missing a mounting screw, but the other one is tight and it doesn't move around. Maybe my next move will be to pull one of the bolts from the top of the primary and screw that in to see if it does anything.

 

[user_deleted]

answers:
1-your coil is a single fire unit....one coil...is under your airbox assembly base plate. coil attached to coil bracket by 2 long allen head bolts. if one is missing in all likelihood someone has been in there messing around which leads me to believe the coil is faulty. i would replace it as they're fairly inexpensive and it MUST be attached with both screws.
2-XB fuel pumps should never "howl". if yours does....and it's 13 years old....it is headed towards death-row. replace it.
3- to address your stuck belt tensioner do this: remove front pulley cover(3 torx screws)....remove rear axle pinch bolt....loosen rear axle.....then lightly snug rear axle....stop there....now loosen rear axle PRECISELY 21 turns. stop there. go to belt tensioner pulley and remove the pair of 9/16th hex nuts and flat washer behind each nut. now liberally spray a quality penetrating fluid onto the mounting studs....wait a few minutes....spray again. wait a few minutes now using rubber mallet lightly tap backside of mounting bracket and wiggle. it will start to come off. use this method ONLY. any other method will result in either broken mounting studs or a cracked engine case....or both.

 

[shortymac83]

1. Cool, that's the next thing I'll do.
2. I think I misidentified the sound. When you turn the key and switch to run, the fuel pump audibly primes. On occasion, it'll make that sound while running, but doesn't affect the behavior of the bike.
3. Thanks!

 

[Chicknstripn]

No frayed wires on the fuel pump?
Have you checked your intake seals? Sounds to me like those are the most likely culprit. I've yet to hear of a set lasting 13years without an issue.
Google search "Buell XB intake seal test" and you should find a lot of helpful info.

Also, totally agree with everything lunatic posted. Especially concerning the belt tensioner. My belt tensioner always feels stuck. Every time I've removed it, I do pretty much what lunatic posted in order to remove it and it works like a charm.

Keep us updated on your progress.
Good luck

 

[shortymac83]

Well, discovered one of the problems...

I took it for a ride and got it nice and warm (it was choking and surging intermittently for much of the time), then pulled it back into the garage where it did its stuttery thing (I'll post a video in a few). Once it decided to behave again, I shot starting fluid at the intake. Didn't change much. I then shut it down with both the key and kill switch and it kept running! Guess I discovered one of the issues...

 

[shortymac83]

Ok, here's the vid. What's going on:

When it dies initially, it was after trying to smoothly throttle up. Then it wouldn't start again, when normally it needs barely a half revolution when hot. Once running again, the first 3 revs were with smooth throttle application. It was stumbling and crapping on itself by itself. Then, the rev at the end, it had returned to "normal" operation.

https://www.youtube.com/watch?v=S7N5Sg9j-Nc

While riding, it'll do the same thing, so at speed, the momentum is keeping the engine running, but I encounter the same issue, leading to a choppy sound, really rough ride, and no acceleration. It will smooth out after 10 seconds or so.

ETA: That vid was before the starting fluid test.

 

[roberson302]

Have you checked the fuel pressure? My 03 XB9R was doing something similar and the fuel filter was stopped up not the sock. I checked my fuel pressure and it was down around 10psi the recommended pressure is around 50psi. Changed the fuel filter the pressure went up to 50psi and I haven't had any problems since. Mine Would have problems idling in the morning sometimes and it would do what you were saying randomly start what felt like skipping while going down the road. It would happen at different speeds in different conditions. It would skip for a minute or so and then clean up and run fine. The only difference is my sock was destroyed when i got in there.