| Author | Message | ||
     Pwillikers |
At the end of a long ride I parked it, the fans did their final cool down then shut off, and I heard whirring from the fuel tank. I think it was the fuel pump whirring for two seconds then off for ten seconds, then back on, then off... you get the idea. It cycled maybe five times then silence. Normal? Was this the fuel pump? If so, why would it pressurize fuel after shut down? If not the fuel pump then what? | ||
| Ratbuell |
Normal. Fuel pump. The fuel pressure regulator fires the pump to scavenge excess pressure after the bike is shut off. Heat soak can raise rail pressure, so the pump circulates a couple times to equalize things. | ||
| Marcodesade |
PW, I had the same thing happen a few times, but with my bike it seems like the few times when it's done it, it doesn't stop by itself at all --- I've sat there for several MINUTES listening for it. What does seem to stop it is to cycle the key on, then off again. | ||
| Kevin_stevens |
It'll stop eventually. I was down working on the turn signals the other night, and after turning the key on to check the lights, it went on for about twenty minutes before it stopped. Not sure how that reconciles with a pressure equalization, though. KeS | ||
| Strongbad |
It is designed to actually maintain pressure in the fuel lines after key-off to keep vapor lock from happening. The algorithm depends on engine temp, fuel pressure, and time. The longest that it will attempt to maintain pressure is 10 minutes. | ||
| Kevin_stevens |
Ok, I'll believe ten minutes. Seemed like longer, but then I was twiddling with light bulbs. KeS | ||
| Buzzie |
It's a pressure sensor. It cam stay on for up too 20 mins ...more or less depending on conditions. And on some bikes this is not normal. It depends on how often it is coming on. Some reflashes (earlier versions) I would imaging had different parameters ..I myself reflashed one that would energize the fuel pump very frequently in short spans of time with low motor temps, etc. | ||
| Pwillikers |
Vapor lock occurs in the fuel line between the tank and the pump. No? With an in-tank fuel pump, wouldn't the pump self prime with liquid fuel if it ever go hot enough to boil the fuel in the pump? I was under the impression that vapor lock had largely become a non-issue with modern, high pressure, electric fuel pumps submerged in the fuel tank pressurizing the lines. Back in the day, a mechanical fuel (vacuum) pump was located on the engine and drew fuel from the tank via negative pressure. This was not ideal, hence, vapor lock was common. What am I missing? | ||
| Strongbad |
The vapor lock issue isn't with the pump, it is with the fuel in the lines. Vapor can form in the line between the pump and the injectors while sitting and can create a very hard start condition if the bike was parked hot and attempted to be restarted a short period later. If the pump maintains a high pressure in the lines while the bike is sitting, the likelihood of vapor forming is greatly reduced. | ||
| Joesbuell |
My mates CR does this, kept us amused one day after a ride while we had a beer  IT'S ALIVE!!!! |
