PDA

View Full Version : After you shut the bike down...



buell-fan
08-28-2015, 08:32 PM
Do you have the fuel pump cycling on and off intermittently when the bike just got turned off? My fans come on until blowing cool air, but they will go off and then I can hear what sounds like the fuel pump coming on for about three to five seconds then going off again. It does this three times, at least, and every twenty seconds or so for a minute or more.

pytalkamus
08-28-2015, 08:51 PM
Yep, mine does the same thing. I think it's normal, but I guess I don't know that for sure.

buell-fan
08-28-2015, 08:55 PM
What do you suppose is the reason for it?

pytalkamus
08-28-2015, 09:06 PM
On the XB's the fan would run to cool the rear cylinder head. If the oil isn't circulating the temperature would spike immediately after shutting the bike off and cook the oil. I assumed the reason for the fan was the same on my RX.

snacktoast
08-28-2015, 09:53 PM
The fuel pump cycles for a short time after shutdown to help relieve any hot spots as the tank/frame heat soaks. This helps prevent fuel boiling in the frame.

buell-fan
08-28-2015, 10:28 PM
The fuel pump cycles for a short time after shutdown to help relieve any hot spots as the tank/frame heat soaks. This helps prevent fuel boiling in the frame.
This is exactly what I was thinking when it was happening!

Mike
08-29-2015, 12:09 AM
Funny....I've heard SOo many reasons for this phenomenon over the years...
There's NO, read that NO reason for the fuel pump to run after the ignition is shut off..! There's also NO reason for the pump to run when you turn the key to the "lock" position, as mine does occasionally.
doesn't matter where the gas tank is...unless the engine is getting ready to run, the fuel pump should remain off. ZERO reason for it to be running. As noted, it has NOTHING to do with the fuel in the "tank".
For whatever this design reasoning is, it's for something in the system "AFTER" the pump, the fuel lines to the injectors...and NOTHING else. And there's no real reason for it at this point either.

Interesting fact...my 05, XB12 does NOT do this silly ridiculous feat. So...so much for the fuel in the frame comments..!

Jeeze, these wives tales are getting out of hand.
Someone needs to ask Erik and put this silly crap to bed.

The fans running after shutdown, no problem there, as long as it's only on hot days. Yea, mine does pull not so hot air past the radiators sometimes, at 5:30 in the morning, but that's not nearly as annoying as the fuel pump running for no reason.

Mike

buell-fan
08-29-2015, 05:43 AM
Mike, I had no idea this was an ongoing Buell phenomenon. Yes, it would be nice to know the true answer to it either from Erik or one of the engineers who wrote the computer's program.

Gemini
08-29-2015, 06:25 AM
To prevent vapor lock on a hot motor when attempting to restart a few minutes after shut off

zac4mac
08-29-2015, 11:19 AM
Gemini - bingo

At least that's the explanation Buell gave when the 1125 debuted.
The frequency that the pump turns on varies due to leak down differences in the fuel rail/injectors.

When the 1125 first came out, the pump cycled for 20 minutes after shutdown.
One of the early re-maps from Buell dropped it to ten minutes, seems the same for the EBRs too.

Z

snacktoast
08-29-2015, 11:43 AM
Mike,

Apparently you are wiser than the vehicle controls team at EBR that designed the fuel pump to cycle for a short time after hot shutdown.
Perhaps you should teach them a thing or two, since this must be the first control system that they designed and you know better. :thumbsdown:

The pump would not cycle after shutdown if it were not programmed that way.
The radiator fans would not run after shutdown if they were not programmed to do so.