Fuel temperature effects.

[BusyLittleShop]

Originally Posted By: Shannow
Probably a silly question, but can you hear the fuel pump when it's running not smooth ?

Hot fuel with low vapour pressure might have the fuel pump delivery in fits and spurts.


Technically speaking fuel pump fluctuations are smooth out at the injector by the fuel pressure regulator...

 

[Shannow]

Originally Posted By: BusyLittleShop
Originally Posted By: Shannow
Probably a silly question, but can you hear the fuel pump when it's running not smooth ?

Hot fuel with low vapour pressure might have the fuel pump delivery in fits and spurts.


Technically speaking fuel pump fluctuations are smooth out at the injector by the fuel pressure regulator...


Regulator's not an accumulator, it's a pressure control device, dumping excess pressure, and controlling injector pressure. It has no storage function like an accumulator would.

If the pump was cavitating due to lower vapor pressure on the hot fuel, the regulator would have nothing to regulate.

 

[02SE]

Without testing your bike, it's difficult to say definitively, but it sounds like you might be having heatsoak issues due to the IAT (Intake Air Temperature) sensor sensing erroneously hot temperatures.

They are known to cause similar driveablity issues on several models of bike, under the conditions you describe.

On other models, moving the placement of the IAT to where it's not as susceptible to heatsoak, improves the running/driveability.

 

[digitalSniperX1]

Shannow I'm going to try to take notice on the fuel pump sound. It may be that my helmet dampens any additional sound coming from it. Also the vibration i feel at some rpm may simply be that it's transferred/undamped/resonates through the bikes structure at some lower and exited at some upper frequency. The sensation that it may smooth out after I've reached a certain rpm may simply be my attention has been distracted from it simply because I'm focused on controlling the bike through a hard acceleration. I'm also going to measure fuel temps after th bike bakes in direct sunlight and correlate them with feel.

As per some sensor heat soak i really don't think so because this happens when the coolant has cooled but the bike has baked in the sun. If the sun is heating a sensor then ok.

Finally this is a minor vibration. Many, many bikes will have more vibration than this one on their best day with this one at its worst. For example, my KTM and my wife's Honda vibrates far more than this bike even when it's fuel is hot.

 

[BusyLittleShop]

Originally Posted By: Shannow

If the pump was cavitating due to lower vapor pressure on the hot fuel, the regulator would have nothing to regulate.


True but there no mention of his engine stumbling from a cavitating pump...

 

[BusyLittleShop]

Dig... if you think engine heat is effecting your fuel temp then fabricate a heat blanket to act as a barrier to know for sure...

http://www.zircotec.com/page/--zircoflex-gold/199

 

[digitalSniperX1]

I think it's engine heat but only when the bike had sat after being ridden, allowing the engine heat to be transferred to the fuel. But this really only been felt after parking bike for hours in Florida. I know the gas gets pretty hot cause one time and it wasn't filled to the top, gas was vented from an overflow tube onto the ground. Quite a bit of expansion to have done that.

So I'd probably have to put the shielding on the gas tank.

Thanks for the link. That's some interesting material.

Having said all that the vibration is minor. It's not really a big issue. Its certainly not even close to a drive ability issue. Just a minor annoyance.

 

[02SE]

Every modern Sportbike I've seen, has had a thermal reflective barrier applied to the fuel tank. Your 14R should be no different.

When I say driveability issue, that's a bit of an exaggeration. A slight brief roughness from sensing an erroneously hotter condition, is more accurate.

 

[digitalSniperX1]

Oh there is no doubt the fuel getting heated up by the sun. Like I stated, the fuel expands into an overflow/pressure relief valve/tube. I've seen the gasoline on the ground under the bike after its sat in the sun for hours. The vibration is felt above 3500 RPM but again,it's more than subtle but it won't shake the mirrors. My v-twin KTM has FAR more vibration at its best compared to this bikes worst.

 

[bonjo]

as previously mentioned, the O2 sensor is part of the fuelling feedback look to maintain a correct A/F ratio to make emission controls are met and the CAT does not get a rich fuel to burn itself out.

Don't forget the passive air injection look (sometimes known as PAIR which injects air into the exhaust to burn off unburt fuel pre CAT)

Now assuming you have not played around or made changes to the fuelling, as mentioned, I would check the fuel pump pressure.

Could be with lower fuel weight or the heat, the pressure also drops (it shouldn't)

interested to find out hat the outcome is?

 

[BusyLittleShop]

Originally Posted By: digitalSniperX1


Thanks for the link. That's some interesting material.


You're welcome...

 

[digitalSniperX1]

Only mods to this bike are suspension (added Ohlins).
I am not sure there will be any changes to correct as it is inherent to the bike. The only thing I could think to do is to make AFR a function of fuel temp and I seriously doubt that input is available to the ECU.