| Author | Message | ||
     Alessio66xb12r |
i'm sure i'm not the only one.... right now i'm pretty satisfied of my engine set-up and maps tuning but i'm still suffering a problem , a BIG problem : under hard braking and right turning (my bike runs only in circuit) sometimes the engine turn off.you stop switch off and then you can turn on again without problems. when the tank is full it never happened. what i want to know is how others racers resolved it ,it is a big problem during a race and i think very common on xbs. thank you Alessio | ||
| Alessio66xb12r |
can it be resolved using ecmspy in the "duty cycle" of fuel pump section ??? any help appreciated bye Alessio | ||
| Trojan |
Is the bike actually 'switching off' electrically or is it fuel starvation? This is very common on earlier model bikes when running under less than full conditions but normally only occurs when accelerating out of slower corners (the fuel has run to the front of the frame under braking and caused a partial starvation to the pump). However, as the fuel pump is located on the rear left side of the frame and you expeience the problem under braking and right hand corners I would suspect that this is indeed your problem. You can get around it by: 1. running the tank full every race and/or 2. stuffing 'Xplosafe' foam into your tank to provide some kind of baffle and stop the fuel surge. If the bike really is switching itself off then I would suspect a faulty bank angle sensor. You can disconnect it without any drama although you may get a warning light. We junked ours on our Uly based 06 racer because it was causing problems. (Message edited by trojan on November 21, 2008) | ||
| Vagelis46 |
Have you checked if you have the latest model of fuel pump ? There was an update for the pump. I have also experienced fuel starvation when braking hard downhill with low fuel. | ||
| Alessio66xb12r |
i must correct myself "when accelerating after slow corners" usually after hard braking and right corners.this is what i mean , of course when braking throttle is closed ...so nothing occurs ....after when i re-open the throttle again it happens. yes i think is fuel starvation and i want to ask where to put the foam in the tank ...i suppose on top of tank living only the left frame leg without it...right ??? anyway how i can disconnect that sensor just to test if it is. i have the earlier pump model and i want to know if is possible switch it with the last one and if it works with the earlier ecm (gb231)....i don't think so. thank you very much bye Alessio | ||
| Buelldyno_guy |
You did not state the year model of the bike, but I am 99.9% sure it's fuel starvation caused by having less than a half tank of fuel and during the hard braking followed by a right hand turn the fuel runs forward and to the right of the pump. That causes the pump to cavitate lowering fuel pressure there by causing a lean misfire or even stalling out for a long as 3 to 5 seconds. Starting in 06 and to the latest pump corrects that by re-plumbing the bypass and intake sock so that bypass fuel is directed to the intake sock not away from it. We have also used fuel tank foam, but found it was not necessary with the later pump configuration. all early 03-03 track bikes should have this mod done. Thanks to Henry Duga from Buell a few years back to help us out with this one. It worked and if you ever see the two pumps side by side you will understand why. Hope this helps Terry JT&S Performance | ||
| Alessio66xb12r |
bike is March 04 model/construction.... yes after hard braking and right hand cornering with less than half tank. sometimes only a lean misfire sometimes when i insist to open the throttle it shout off and i need to stop at the track side turn the key off-on and than the engine turns again on. let me understand "replumbing the bypass and intake sock so that bypass fuel is directed to the intake sock and not away from it"..... thank you .....honestly have no idea how to do , i'll check the manual to understand the differences between old and new pump assembly i hope this help to find the way. thank you very much. | ||
| Alessio66xb12r |
to Buelldyno_guy had a look at the manual intake sock do you mean fuel screen ??? | ||
| Buelldyno_guy |
Yes, what I called the "Sock" is what you called the screen. However there are no Buell parts for sale to update your pump to the new configuration and that's too bad. I have at least three early pumps sitting somewhere in a box in the shop. It would take a several hours to find tubing and the small parts to convert them. A new pump from the dealer fixes the condition. About turning off the switch, that does three things to get the bike running correctly. 1st stopping the bike allows the fuel to return and sump around the pump.2nd when the key is turned on the pump runs for several seconds then shuts off until the bike starts, this ensures a full head of fuel at the injector ie no air. Last is that regardless of how hot the engine is the bike always starts in a warm-up mode increasing the idle mixture to a % of enrichment over normal idle. BTW the drag race tank foam works well and is easy to trim and install. But you have to remover the pump to install it, so why not just replace the pump with the later one and the entire problem goes away for good. Hope this helped. ... Terry JT&S Performance | ||
| Alessio66xb12r |
pump was removed today ...and if I understand it correctly a tube must be fitted in the small hole of the black plastic ( fuel pressure reg. housing) and directed to touch the screen . yes not easy ....i have some small tubing and the small part you said ...maybe some special product to fix that small part to the black plastic...it looks like an half-pain .....but the pump assembly is on the table , sure I will try foam thank you   | ||
| Alessio66xb12r |
to BUELLDYNO_GUY it should be the last version configuration right ???   | ||
| Buelldyno_guy |
Alessio, I am just a little more than impressed, it sure looks like you got the intent of the mod. For us here in the shop, we get the labor, and also make $.50 on reselling the pump at retail. At our shop rate it just take too much time to do the mod ourselves. Too bad Buell doesn't sell a kit that we could buy and install. On the foam you will need to carve it into shape to fit across the back and to the right of the pump. Them one or two pieces carved to fit forward of the pump, I don't think there is a need to fill the tank with foam like the dragsters do. All you need it enough to slow down sloshing when the tanks is low. Again good job. ... Terry JT&S Performance |
