Author |
Message |
C4bird
| Posted on Friday, January 18, 2008 - 05:27 pm: |
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I have noticed the last couple times I have shut off the bike (kill switch and key both OFF), it cycles the fuel pump several times. Is this normal? If so what is the reason? Wondering if some of the hard hot starting issues and dead battery may be related to it. Thanks! |
Interex2050
| Posted on Saturday, January 19, 2008 - 02:51 am: |
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Mine does the same exact thing... Except it will sometimes do it out of a sudden long after its been off... |
Spectrum
| Posted on Saturday, January 19, 2008 - 08:55 am: |
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Yep I hear that brief spin-up sound on an occasion to. I thought it was the cooling fans though. |
Jpfive
| Posted on Saturday, January 19, 2008 - 11:27 am: |
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I believe it is the cooling fans cycling. |
C4bird
| Posted on Saturday, January 19, 2008 - 11:31 am: |
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I checked the fans to be sure and it isn't the fans. Did a little experimenting to see if I could solve, didn't come up with anything definative, but had some odd observations. 1. Have not repeated the number of times it has cycled. Had 8 one time, 3 the next time, 4 the last time. 2. It only happens when the key and the kill switch are in the off position. If I put the kill switch to the on/run position with the key still off, it stops (maybe coincidence??). 3. The times between cycles is different, had one around 60 sec, others between a minute and 2 minutes. 4. Like Interex mentioned above, had the fuel pump cycle, on 2 different occasions, about 30 minutes after it had shut off (kill switch in the off position). 5. Per the diagnostic readout, no error codes. Not sure whats going on, but did notice for the first time my voltage has dropped from the usual 12.5/6 to 12.3 (per diagnostic mode). Wondering if the dead battery issue and hard starting is related, sure could be if the injectors are priming every time the pump cycles.. |
Jedipunk
| Posted on Saturday, January 19, 2008 - 11:42 am: |
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I believe the fuel pump cycles to maintain the specified fuel pressure (75psi?) if the bike is on or off. |
Diablo1
| Posted on Saturday, January 19, 2008 - 02:18 pm: |
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I believe the fuel pump cycles to maintain the specified fuel pressure (75psi?) if the bike is on or off. If so, I can't believe anyone would design it that way. There is no need for fuel pressure in an engine that's not running.} |
C4bird
| Posted on Sunday, January 20, 2008 - 03:48 pm: |
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I wouldn't image so either. Anon/Court have any info for us? |
Metalstorm
| Posted on Sunday, January 20, 2008 - 05:52 pm: |
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Maybe with two big honk'n throttle bodies to feed, having the fuel system pressurized at all times whether it's on or off helps aid in quicker, easier starts? Much less chance of getting vapor lock? It beats me but if it is intended to be this way I'm sure it's for a damn good reason. |
Jedipunk
| Posted on Sunday, January 20, 2008 - 06:33 pm: |
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The document on h-dnet states that it may come on up to 20 minutes after bike has been shut off to maintain system pressure. Fuel pressure spec is 58-80psi. Key on fuel pressure needs to be 75psi. |
C4bird
| Posted on Sunday, January 20, 2008 - 09:03 pm: |
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Strange, wonder why this would be? Tried again to get it to cycle with key off and kill switch on, nothing.. Not sure what that means. |
Bobup
| Posted on Sunday, January 20, 2008 - 09:37 pm: |
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I hear the same "cycling" even when turning the key to "park" position |
C4bird
| Posted on Monday, January 21, 2008 - 07:52 pm: |
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I get the same thing too Bob, only difference between cycling and not is the kill switch on/run position. Had to charge the battery yesterday, voltage got down to 12.1 overnight (also very cold that night). |
Azxb9r
| Posted on Saturday, January 26, 2008 - 01:08 am: |
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The document on h-dnet states that it may come on up to 20 minutes after bike has been shut off to maintain system pressure. This makes perfect sense to aid hot soak restarts. It is also something important to know before doing any fuel system service. |
Diablo1
| Posted on Saturday, January 26, 2008 - 08:44 am: |
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This makes perfect sense to aid hot soak restarts. It is also something important to know before doing any fuel system service. How come my other fuel injected bike and cars don't run the fuel pump with the engine off? They have no trouble starting hot or cold. How long do you think it takes the fuel pump to fully pressurize the injectors? I've checked a different fuel injected bike with a pressure gauge....the pressure comes up in less than a second.} |
Azxb9r
| Posted on Sunday, January 27, 2008 - 01:00 pm: |
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It's a matter of keeping the fuel from boiling in the fuel rail after the engine is shut off. Depending on fuel line routing, and where heat is vented from the engine, some designs will have more trouble with this than others. Auto manufacturers have tried different tricks to combat this. Cooling fans that blow on the fuel rail(Ford and Nissan), fuel pressure regulators that raise the fuel pressure when engine temp. rises above a certain point(Toyota), and raising system pressure altogether. When you shut down a liquid cooled engine,the temp. rises. After sitting for 10-15 minutes, a drop in residual fuel pressure could result in the fuel boiling and causing a hard start. Although fuel pressure rises quickly(as you mentioned),if the fuel rail is full of boiling fuel it will still have a problem. As I mentioned earlier, some designs may have more potential to experience this than others. If keeping the fuel pressure up for a few minutes eliminates a potential problem, it is a simple fix IMHO. |
Zac4mac
| Posted on Sunday, January 27, 2008 - 01:06 pm: |
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Didn't know that, but it makes perfect sense. Thanks for the insight. Z |
Zac4mac
| Posted on Monday, January 28, 2008 - 12:31 pm: |
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Heard mine cycle after shutoff for the first time yesterday. Stopped at a turnout going up into the mountains for a smoke and some pics. Heard the fuel pump whine about 5-7 minutes after I shut the bike down; lasted less than a second. Zack |
Buzzie
| Posted on Thursday, February 21, 2008 - 02:25 pm: |
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guys the fuel is not controled by a pressure regulator it is controled by the ecm and a pressure sensor tells the ecm to kick the pump on or off. therefore the ecm will continue to keep the pump running to maintain fuel pressure and avoid vapor lock. |
Ccryder
| Posted on Thursday, February 21, 2008 - 02:49 pm: |
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Brian: You are correct, mostly. The pressure regulator controls the pressure in the fuel system so the fuel pump does not have to cycle on and off rapidly. The fuel pump could over pressure the system w/o the regulator. Most FPR's also have a vacuum line to adjust the fuel pressure by the engine load. This is all based on tribal knowledge since I have not seen how the 1125r is actually configured. Neil S. |
Spatten1
| Posted on Thursday, February 21, 2008 - 03:00 pm: |
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Yeah, I believe that the pump should always attempt to over-pressurize the system and the regulator will bleed off the excess, resulting in the desired pressure. |
Buzzie
| Posted on Friday, February 22, 2008 - 10:41 pm: |
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excuse me ....guys...your not listening. the 1125 doesnt have a fuel pressure regulator. it has a pressure sensor. and so the ecm maintains the pump to continue a pressure variance of 52 to 80 psi...again...no regulator. |
Ccryder
| Posted on Friday, February 22, 2008 - 11:39 pm: |
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Hey Brian: We were just basing our guess' on previous experience. Thank you for helping with some real information. No FPR is an interesting system. Just sensing the pressure would require the pump to cycle on and off a lot, depending on load. This is especially true since the system is pretty small, volume wise. (BTW did I ever mention that in a previous life I designed fuel rails and the associated systems but, that was in another life and dealt with 4,6 and, 8 cylinder engines.) What other "pearls of wisdom" can you share? Thx Neil S. |
Spatten1
| Posted on Friday, February 22, 2008 - 11:43 pm: |
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Is that a design used by other manufacturers, or is it different in every sense? |
Ccryder
| Posted on Friday, February 22, 2008 - 11:55 pm: |
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I have seen this design before. One of the truly innovative was a positive displacement pump system driven by a stepper motor. The complexity is not really required. Depending on which school of thought you come from running a motor at a constant rpm is better than starting and stopping. They may have an "accumaltor" in the system to buffer the hi and low pressures. Just my $0.02 on a Friday night. Later Neil S. |
Chevycummins
| Posted on Tuesday, April 22, 2008 - 09:20 pm: |
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The fuel pump is pulse width modulated on the ground side. The ecm actually turns the ground on and off very quickly to adjust the speed of the pump and that is how it regulates the fuel pressure to the injectors. |