Weird Fuel Management problem

[Seaking]

Yesterday, I had been out on a full long day's ride on the 06 Midnight Venture and ran into a weird problem. (the bike is a Yank bike but I'm in Canada)

 

As I understand it, and as it has always done, the low fuel light comes on around 170 miles and allows me roughly 12-20 miles more before actually getting to the reserve.. I've never actually gone to the point of having to switch to reserve at that point. I've gotten to 210 miles before hitting reserve. At around 170 miles, I usually put in around 17 litres of gas.. The bike as 22.5 fuel capacity with a 4 litre reserve, which means at reserve I should be putting in around 18.5 litres, or roughly so. This the norm with my bike.. I've changed my fuel filter last month.

 

However yesterday was weird.. Weather condition was hot for up here. We drove 90 minutes, the bikes were parked in the sun for 3 hours and then we headed back after the festivities. On the way home via highway, the fuel light came on at the expected 170 miles but right away the bike started to buck.. "reserve"?! I switched it to reserve and yep, the bike smoothed out and away we went.. Wait now, I thought.. I switched it back to normal and the bike ran smooth.. but as soon as we hit a small hill it hit again.. wow, back on reserve and smoothed out again.. and immediately pulled in to the next gas station for fuel.. I only put in 16 litres, well below what I should have been if on reserve?! But all has been good since..

 

What bothers and puzzles me is that the low fuel light came on and right away I'm on reserve. And I went on reserve much earlier with so much more fuel in the bike than what the 'reserve' amount should have been.. see the problem?

 

The only explanation that anyone locally could come up with was that the fuel in the tank was so hot that it might have 'foamed' thus giving the system the impression of lesser fuel amounts..

 

Anyone see this before or know if I have an impending problem on my hands as far as fuel management goes?

 

Cheers

[Black Owl]

Not sure what you mean by "foamed". Fuel will normally expand if the tank is left exposed to the sun on a hot day.

 

I do a lot of testing on fuels, and given the density of fuel vapors, have never had gasoline foam.

 

But, I can not think of any logical reason for the condition you describe.

 

[Rodburner]

I was thinking about posting this very same question i have seen this inconsistency with my 06 when i am 1 up i will get more mileageup to 20 miles before flipping the petcock after the indicator gos on but when i am 2up its all over the place sometimes right after the indicator comes on or 2-10 miles later

[nelsontoddpa]

I have to admit I've noticed a similar issue with my 05. My fuel indicator will come on (and the odometer changes to Fuel) with about a quarter tank still indicated on the digital fuel gage. Shortly after that it begins to sputter some and I have to switch to reserve.

When I fill up- based on the spec tank capacity- I should have around 2 gal left in the tank.

 

I guess I just chalked this one up to one of the RSV quirks that we all put up with- but maybe it's not...........

[Lynx]

I have an 07 and my indicator has always come on shortly after i hit 1/4 tank. I have never had to switch to use my reserve even though i have gone right down into the last bar. This past Sunday, riding two up we put on 368km (228miles) and still have not gone to my reserve but i am 12km into my last bar. My next stop will be the gas station. I watch my fill ups real close as i like to keep tabs on how much fuel i put in & due to pump fixing at some stations.

[Seaking]

Not sure what you mean by "foamed". Fuel will normally expand if the tank is left exposed to the sun on a hot day.

 

I do a lot of testing on fuels, and given the density of fuel vapors, have never had gasoline foam.

 

But, I can not think of any logical reason for the condition you describe.

 

 

It happened to a couple of local Venture owners I spoke with afterwards.. they say it's something that happens on very hot days, especially to the black bikes. It's apparently more common than you'd think from what I'm hearing. One gent tells me he lays his white sheepskin seat cover over the tank to take some of that heat away when parked in the sun for long periods of time.

 

Go figure, yesterday, riding back roads mostly I managed to get 210 miles before needing reserve and the fuel indications were back to normal.. Was the other day a fluke of nature? Hard to tell.. but something to be aware of.