| Author | Message | ||
     Sjbrush |
I constantly use this site for tips and tricks but I'm finally out of ideas on this issue I have with my bike. About two weeks ago the bike would start but die right away. I tested the fuel pressure and it was only reading about 30 psi which I read is about 20 psi low. So I ordered a new pump and regulator and just finished installing it. It started right up and the fuel pressure tested at 50 psi so I think it worked. The issue is now when I turn the key on the pump runs constantly. Previously it would prime for about 2 seconds and then shut off until I started the bike. I can't figure out why its now running all the time and if that is going to be an issue. At first I thought, ok I just wont keep the ignition on unless I'm ready to start the bike, that way the pump wont sit there running. But then I thought why would this change and will it hurt the pump down the road. So here are my questions. Does anyone know how to correct this issue? Is the fuel priming time controlled by the ECM? If I can't correct it will it hurt the pump? Are these pumps variable flow or do they just run at about 50 psi constantly? Any help would be greatly appreciated. Thanks! | ||
| Natexlh1000 |
The fuel priming thing is a pressure thing and not a time thing. You may have a leak inside the tank between the pump and regulator. | ||
| Oldog |
The fuel priming thing is a pressure thing and not a time thing. You may have a leak inside the tank between the pump and regulator. Nate I have to respectfully disagree, the ecm simply turns on the pump for about 3 seconds when the system powers on. 2 possible causes come to mind, 1. short in wiring causing the signal line from the ecm to go to ground 2. internal short in the ecm and that control output is burned on. #1 find the wiring fault, #2 replace the ecm. The pump gets 12v and the ecm truns ground on and off as needed, there is no pressure feed back to the ecm. } | ||
| Natexlh1000 |
So If I turn the ignition on with the gas line off of the filter, whouldn't it just pump the fuel out continuously? This is one of those messy experiments I have yet to try  | ||
| Hootowl |
How does the ECM turn the pump on and off as needed if there is no pressure feedback to the ECM? I was under the impression that the pump runs all the time when the bike is running, and the excess fuel is simply returned to the tank from the regulator. On Buells, this all happens inside the tank, since the fuel line to the injectors is very short. On a car, the regulator is on the fuel rail, and there's a return line to the tank. Pump runs constantly. I, of course, could be wrong. Believe it or not, it has happened before. | ||
| Natexlh1000 |
This is getting me curious enough to make a bit of a mess in my garage. Perhaps tonight, it will try it. | ||
| Oldog |
The fuel pump cycles on and off as the bike runs, I discovered that adjusting the timing. I had ecm spy displaying the sensor state while I was moving the plate after a roll over with a low battery, I heard the pump stop and start as the engine turned over. So If I turn the ignition on with the gas line off of the filter, whouldn't it just pump the fuel out continuously? Yes the pump is powered thru the ign circuit, IF the ecm is calling for fuel, BUT with no pulse train to the ecm the fuel will not pump as it is not called for. The OP stated that the pump came on with the switch and did not turn off, you know normally at start up the pump is turned on for a couple of ticks to build pressure and test the pump then it shuts off. so the likely problems are short, or bad ecm short to ground or to supply, IIRC the ecm supplies the ground and the ign line feeds 12v. there are 4 wires that go the the pump, 2 are the pump motor 2 are the low level light the only other devices are the injector heads them selves. no feed back. My 1125R has fuel pressure feed back to the ecm. There is a sensor in the line. } | ||
| Natexlh1000 |
OH! I was just coming on here to tell you that you were right. I popped the hose and it ran for the same amount of time each time. | ||
| Oldog |
Thanks Nate, I hope you did not have a HUGE mess. | ||
| Natexlh1000 |
Naah. I ran it to a hose to my lawnmower tank. I only got a bit on me when I popped the hose off. | ||
| Tjx1 |
To keep this on point and concise, I bought the 99x1 from the OP during the time the fuel pump was replaced and the prime “buzz” did not go away which I knew about. The question from him to this forum was to ask if others thought that this would be a problem. It seemed like it would not be an issue if the bike was started promptly and the key was not left on. In Sept last year the bike died on me and would not get fuel. Also no prime “buzz” when ignition is on. It has been in storage since. Is there a way that I can check to see if the ecm or the fuel pump has failed? I now have funds to make the fix if I need to purchase an ecm. Thanks for you guidance. |
