| Author | Message | ||
     Gas |
Sounds like my fuel pump has begun to cycle off/on after I shut down. Every 10 seconds it will come on for a second and stop. This continues until the instrument cluster finally goes dark. I was able to stop this behavior once by starting the bike again for a second. After I switched it off, the cycling stopped. This is a new foible that just started with 1400 miles on the bike. Will the flashers come on soon and blink for 2 minutes after I kill the bike? I'm afraid the fans(and now pump) will eventually kill my battery and leave me stranded. Anyone familiar with this? | ||
| Jules |
I believe the owner's manual mentions that the fuel pump will still run for some time after the bike has been shut down... I forget how long fo r but I believe that's "Buell normal" | ||
| Jules |
OK found it: Stopping the Engine: See Engine OFF/RUN Switch: Buell Models. Push the upper part of the engine OFF/RUN switch to shut the engine OFF. See Ignition Key Switch. Turn the ignition/headlamp key switch to the OFF position. NOTE: The fuel pump may occasionally operate for up to 10 minutes after shutting off engine. | ||
| Vinb |
The fuel pump will do that till the bike cools down its nothing to worry about | ||
| Gas |
OK and thanks for the information. I was worried since my bike had never done this, to my knowledge, during it's first 1400 miles. | ||
| Vinb |
I had the same thing and I went to the dealer they had to call Buell to find out why and that's what they told me | ||
| Froggy |
I think it is heat related, neither of my bikes have done it since the fall. It would do it at every stop during the summer though. | ||
| Poppinsexz |
Heat will boil the fuel in the lines making for vapor lock. The pump runs to keep up the fuel pressure which raises the boiling point keeping the fuel a liquid. Makes for a better restart on a hot engine. | ||
| Drawkward |
Hit it on the head poppin. It's to prevent vapor lock. | ||
| 1_mike |
Popp (et-al) - That's what you think....!? NO....other engine management system I've heard or worked on runs after shutoff.. Not street or race setups, not car or bike. Who cares if if there's pressure in the system AFTER shutdown? Certainly not the fuel system... Who cares about any POSSIBLE...vapor lock after shutdown ? Does "everyone" live in 120 degree plus climates where they need a constant pressure in their fuel systems for a "coupla minutes" after shutdown? Now when the ignition key is turned on anywhere from seconds later to months later...THEN the system fills, "repressurizes" and becomes ready to go again. And in any and all cases....system pressure is lost minutes later anyway. Explain that.... Someone should ask the fuel management designers exactly why this happens to put this nonsense to bed. I just love the way wives tales are created... Mike | ||
| Therealassmikeg |
Quote: "Now when the ignition key is turned on anywhere from seconds later to months later...THEN the system fills, "repressurizes" and becomes ready to go again. Hot restart and vaporlock are totally different issues than cold starting with low fuel pressure. Quote: "And in any and all cases....system pressure is lost minutes later anyway. Explain that...." Fuel injection systems are designed to hold fuel pressure for some time after shutdown. On one end you have a closed injecter and the other a check valve (either in a pressure regulator or the fuel pump). If either of these leak quickly after engine shut down you may or will have a hot restart issue. The fuel system should hold pressure 30min to several hours. In some cases during hot soak you will even see fuel pressure rise before losing pressure. Quote: Someone should ask the fuel management designers exactly why this happens to put this nonsense to bed. I think theres a bulliten for the lastest ecu flash that explains how long the fuel pump is programmed to run for after shut engine shut down.. Quote: I just love the way wives tales are created... Me too... Cheers, Mike G | ||
| Ratbuell |
Hm. Wive's tale? So...I guess this is BS? 6. FUEL PRESSURE The fuel system is different on the 1125R.The 1125R uses a fuel pressure sensor compared to the XB, which uses a fuel pressure regulator. The XB needed a constant pressure (49-51 PSI). With the 1125R the fuel pressure will vary. At key on the fuel pressure is 75psi and the range of the fuel pressure is 58-80psi. NOTE:The fuel pump may come on for up to 20 minutes after key off to maintain system pressure. Taken directly from TT354: 2008 Buell 1125R New Model Information December 17, 2007 I guess even Buell doesn't know what they're talking about.... | ||
| Poppinsexz |
1_mike, you might educate yourself on vapor lock and what problems it can cause. Pressure is not the issue. Maintaining the fuel as a liquid is. Pressure is just how this is accomplished since the fuel rail is located in a 'hot' area where it may boil and vaporize after shutdown. This could cause problems next time you wish to start your bike | ||
| Hootowl |
Loud fuel pumps save lives. | ||
| Ratbuell |
To further clarify for the "need pictures for big words" crowd...think of bleeding a brake line. Get air in the line, brakes don't work too well because air will compress in place and not transmit the pressure force to the backside of the brake caliper pistons. If its all fluid in there, the force you apply at the master cylinder is transmitted completely to the caliper. If you get vapor lock in a fuel rail, you have a fuel pump / regulator that "sees" what it thinks is proper pressure. But the air pocket between the regulator and the injector - where the fuel is really needed - soaks up some of the pressure and the injector only sees a portion of proper pressure. Presto. Hard start / no start. Keeping fluid at pressure helps keep it fluid, instead of allowing it to evaporate and creating that air pocket. This is also why cooling systems are pressurized. At atmosphere, they are more likely to boil off. At pressure, they stay liquid. | ||
| A_s_r |
I'm not much one for wive's tales, so here is some interesting information on vapor lock and boiling points... http://en.wikipedia.org/wiki/Boiling_point http://en.wikipedia.org/wiki/Vapor_lock http://www.engineeringtoolbox.com/fuels-boiling-po int-d_936.html So, if the boiling point of gasoline at 760 mmHg (0 psig) is 100 degrees F (worst case scenario according to the engineering toolbox website), then the boiling point would be approximately 593 degrees F at 3760 mmHg (58 psig, the low end of the fuel system pressure that Joe presented above). | ||
| A_s_r |
Forgot my screen shot of the boiling point calculation...  | ||
| Azxb9r |
The fuel system is kept pressurized to aid in hot-soak restarts. We have a little trouble with that type of thing here during the warmer months  | ||
| Eece_ret |
Hmmm I thought I read somewhere this was to aid in the fuel boil over situation that was occuring on some of the R/CR's... But then again, I brained my damage years ago  | ||
| Chevycummins |
Don't forget this fuel system is a return-less fuel system. There is no fuel pressure regulator in the fuel rail that will bypass fuel back to the tank when the fuel system primes up. If it boils the gas out of the fuel injectors and lines, all of the air trapped in the system will have to be pushed out through the injectors. That would cause an excessively long crank time before starting. | ||
| Captain_america |
Yup sure would. We have battled these situations for so long with after market EFI on muscle cars... the best thing to do is have a very small bleed off back to the tank so the air can escape from the line. ooooor run WFO until the air is gone lol | ||
| Syonyk |
Why would you build a modern fuel injection system returnless? The only reason I can come up with is to be able to easily vary the fuel pressure with just the fuel pump. Couldn't you do this with a small return orifice as well (and still be able to rapidly push any vapor back into the tank)? | ||
| Chevycummins |
Newer modern cars are going to this system also. Without the mechanical fuel pressure regulator the fuel pressure can be controlled via the ecm with fuel pump speed like the 1125. E85 vehicles are usually set up this way. This is one of the reasons the car can run on different fuels. Also can help meet emissions through programming of fuel pressure. Need more fuel, adjust the pump speed along with the pulse width of the injector, its all in the programming. Also cuts down on the amount of parts, no pressure regulator, no return line, less weight and simpler. Drawbacks that I've run into, contaminants can't get out of the fuel rail if they get past the filter. If water gets in the system some of the micro screens on the injectors are so fine the water won't pass through them so it will block out the fuel and misfire. | ||
| Syonyk |
That makes sense. Couldn't you have some of the same benefits (less parts) by having a small return orifice? You could still vary the fuel pressure (you would need a bit more flow to do so), but you'd also have the benefits of a return system - and any vapor in the lines would be able to flow through the orifice very quickly, eliminating vapor lock problems. | ||
| Eece_ret |
Returnless Fuel plumbing!!! Damn thats crazy  Never heard of that one, that's pretty cool! Learn something new every day. | ||
| Captain_america |
Right. Return-less is most beneficial to guys that don't want to run a return line in their car.... also if you have boost or there is vacuum on the injector you can easily vary the pressure at the injector to compensate. if you have injectors that are too small you can run a different Press/Vac ratio. for example you can bring fuel pressure up at 2.5:1# of boost where as a mechanical regulator you cannot. vapor lock happens regardless of how you have the fuel system setup unless you are running a full return type system. That is what the bleed off is for... the system may boil the fuel, but the air can always escape. the fuel boils in the line on a return-less setup because at idle and low speed (traffic) the fuel is moving through the line at 0mph its soooo slow and has the most time to heat up. | ||
| Chevycummins |
Anybody know what the boiling point of the fuel would be in the fuel rail of our bike at 60psi fuel pressure? That is why the ecm still drives the pump 10 min after the bike is shut off. I would guess at 60psi the boiling point would be much higher than most would think. | ||
| A_s_r |
Yeppers, about a dozen posts up http://www.badweatherbikers.com/cgibin/discus/show .cgi?tpc=290431&post=1738514#POST1738514 | ||
| Chevycummins |
There it is! Thanks just had to go up one more click! | ||
| Chevycummins |
Gas, My bike started the priming after shut off at about the same mileage. When I checked fuel pressure I found that some times it would hold pressure when shut off and sometimes it wouldn't. It would do it hot, cold, warm or whenever. Sometimes it would hold just fine and never prime after shut off. The check valve in the pump is leaky sometimes and the fuel flows back into the tank. My pump finally quit all together at 6,000 miles, I believe that the failure had nothing to do with the priming though. | ||
| Gas |
Thanks chevy for the good info. One more idiosyncracy. I had a BSA once that had as many as my new Buell. I was hoping for a bit more trouble-free platform. Oh well. The CR still has to breakdown a bunch more times to be as big a piece of cr-p as my Sony video camera.All things are relative. |
