Gas reserve "amber" light; does the intensity increase as you deplete the reserve?

[Lucky Phil]

10 hours ago, docc said:

Well, on a steady state throttle, as in rolling down a freeway, I have seen as much as 40 mpg and am confident my tank will deliver five US gallons (maaaaaybe 5.1). So, sure, 200 miles in those conditions. Yet, I absolutely love-love rowing this gearbox and ripping up-and-down through the revs. I am total hell on tires and brakes and fuel economy.

On a chilly day when the weather feels like the Sport is climbing the Stelvio pass, and I'm pretending to be Omobono Tenni, I can see as little as 32.5 mpgUS.

                                                                             But it's worth it . . .

I think I've mentioned this before but what makes a surprising difference to fuel range is cold start cycles. So you may fill your tank and then do 4 short, say 10 mile round trips to work for instance, look at you trip and think, yep still got 120 miles of fuel.....nope, no where near it. It's a way greater effect than a single 40 mile urban commute. Obviously suburban riding hurts the economy but it's the cold start cycles that have the biggest effect. If you add the start enrichment map and the engine temp trim map figures together the overall fuel metering can be well over double the delivery at running temp fuel mapping.     

Ciao

[docc]

29 minutes ago, Lucky Phil said:

I think I've mentioned this before but what makes a surprising difference to fuel range is cold start cycles. So you may fill your tank and then do 4 short, say 10 mile round trips to work for instance, look at you trip and think, yep still got 120 miles of fuel.....nope, no where near it. It's a way greater effect than a single 40 mile urban commute. Obviously suburban riding hurts the economy but it's the cold start cycles that have the biggest effect. If you add the start enrichment map and the engine temp trim map figures together the overall fuel metering can be well over double the delivery at running temp fuel mapping.     

Ciao

That is revealing.

So, it's not actually my maniacal, jack-rabbit riding style? 

[Lucky Phil]

3 hours ago, docc said:

That is revealing.

So, it's not actually my maniacal, jack-rabbit riding style? 

Well riding style and conditions have an effect of course but the cold start cycles are something I think people aren't necessarily aware of. The amount of fuel that gets thrown at the engine getting it up to temp esp in cold weather has a big impact on the range. I got caught out 20 years ago on my Aprilia RSV1000 when it ran dry about 20klm before usual and it was lucky to get 270klm out of a full tank of country riding so was marginal on fuel range as it was.

I'd filled it up after the previous ride but then did 4 or 5 cold start cycles with little mileage and it caught me out on the next weekend ride. Always best to fill up at the start of the ride with a warm engine on the edge of the city for maximum range. The difference is very noticeable.

Ciao    

[docc]

If I understand correctly, every time the ECU starts our V11 the enrichening cycle runs for some specified number of RPM, even if the motor is actually up to operating temperature. (?)

[Scud]

35 minutes ago, Lucky Phil said:

Always best to fill up at the start of the ride with a warm engine on the edge of the city for maximum range. The difference is very noticeable.   

That is a pearl of wisdom, thank-you very much.

[p6x]

@docc

I was coming back from Lufkin, about 30 miles from home. I was dead set on crossing the 200 miles barrier on a single tank of gas. However, the reserve amber light came on. Not a slow graduate light. It just came on very bright. I decided against taking the risk to push the beast all the way to the next gas station.

Exited the US-59, and in doing a sharp right to enter the gas station, the amber light went off. I am guessing the sensor monitors one side of the tank? there is some kind of berm or dam between the left and right side? no communication? are you able to fully deplete the theoretical volume?

I refilled 4.4 Gal. There would have been about 1 more Gallon left in theory. But if some of it is not attainable...

 

[BramF]

4 hours ago, p6x said:

@docc

...Exited the US-59, and in doing a sharp right to enter the gas station, the amber light went off. I am guessing the sensor monitors one side of the tank? there is some kind of berm or dam between the left and right side? no communication? are you able to fully deplete the theoretical volume?

 

 

Correct, there is a fuel sensor on to one side of the tank towards the seat area, the other side contains the fuel petcock (at least on my V11 Lemans ’02).
Because of the way the fuel tank hangs on the frame there are essentially two compartments on either side of the frame. Moving the bike side to side will cause some of the fuel to move over to the other compartment.

[gstallons]

Trust US , you will get the hang of it after running out  of/low on fuel a couple of times !

[docc]

So, the early tanks (chin pad/ external pump, 1999-2002) will only deliver about 5.1 US gallons to the petcock (fuel tap) on the left side of the tank at the rear. About 0.8 US gallon is trapped on the right where fuel returns from the injectors through the regulator. The fuel level sensor is on the left ahead of the fuel tap.

The fuel delivery is more likely to run dry going downhill and banking right.  Out of fuel and at a stop, the bike can be (strenuously) leaned hard to the left and trapped fuel "sloshed" into the left to get restarted and maybe a couple tenths of a mile down the road. The "tip-slosh-restart" can be performed more than once on an "empty" tank.  Going easy on the throttle returns more fuel to the right side trap.

I watch my odometer for the point at which I expect a faint, intermittent glow of the warning light. This will be first detectable idling at a stop; getting on the throttle tends to extinguish the light. By the time my light is on full bright, it's tip-slosh time.

[p6x]

1 hour ago, docc said:

So, the early tanks (chin pad/ external pump, 1999-2002) will only deliver about 5.1 US gallons to the petcock (fuel tap) on the left side of the tank at the rear. About 0.8 US gallon is trapped on the right where fuel returns from the injectors through the regulator. The fuel level sensor is on the left ahead of the fuel tap.

The fuel delivery is more likely to run dry going downhill and banking right.  Out of fuel and at a stop, the bike can be (strenuously) leaned hard to the left and trapped fuel "sloshed" into the left to get restarted and maybe a couple tenths of a mile down the road. The "tip-slosh-restart" can be performed more than once on an "empty" tank.  Going easy on the throttle returns more fuel to the right side trap.

I watch my odometer for the point at which I expect a faint, intermittent glow of the warning light. This will be first detectable idling at a stop; getting on the throttle tends to extinguish the light. By the time my light is on full bright, it's tip-slosh time.

As far as I can tell, and without much experience, my reserve light  seems to correspond to what Guzzi announced in terms of capacity. Each time it started to glow, a refill would be around the 4.3/4.4. 
150 miles seems to be the safe autonomy for any type of driving. 
But I would like to verify how far I can get, safely while driving conservatively. Not that I want to test the limits, but in case I am in a desert.

[p6x]

7 hours ago, gstallons said:

Trust US , you will get the hang of it after running out  of/low on fuel a couple of times !

I really hope I will never have to verify it “hand’s on”. 

This is why I am recording all my rides and refuels.

Knowledge before I venture inside Big Bend NP. Running out of fuel inside and needing to ask a bear to help me push.

[p6x]

8 hours ago, BramF said:

Correct, there is a fuel sensor on to one side of the tank towards the seat area, the other side contains the fuel petcock (at least on my V11 Lemans ’02).
Because of the way the fuel tank hangs on the frame there are essentially two compartments on either side of the frame. Moving the bike side to side will cause some of the fuel to move over to the other compartment.

I noticed when I open the filling cap, the tank is on negative pressure. 

[GuzziMoto]

55 minutes ago, p6x said:

I noticed when I open the filling cap, the tank is on negative pressure. 

Tank suck, as it is sometimes called, is not uncommon. It usually happens because the tank has a one way valve that is supposed to only let air in to replace fuel being used and not let fumes out. But it is fairly common for the valve to be installed backwards, so it ends up letting air out but not in. Or the valve can be installed correctly, and when you open the gas cap it actually vents out (not in) creating a whoosh.

Not telling you what to do, but we have removed the one way valve on ours, so it does not prevent air from entering or fumes from escaping. It just vents either direction as needed.

[Kiwi_Roy]

I changed all the lamps in mine to LED type, they are much easier to see in bright sunlight. The LEDs should outlast the bike so I glued them in place and soldered the wires direct to the lamp, no lamp holder to give trouble. For the low fuel light I kept one of the incandescent lamps in parallel, this biases the thermistor in the low fuel sensor.

As for the trapped fuel on the RH side, I took the pressure relief/return fitting out of the tank and modified it with an internal pipe bent at the top end. The returning fuel is now shot over the hump to the LH side, it still traps fuel on the Right but if you lean the bike right over to the left it has a better chance of staying where the pump can get at it.

(I know longer own this bike so don't ask for a picture)

[docc]

I recall the published capacity of the early external pump tank is 5.8 US gallons/ 22 liters. (Not sure where I remember that from.) Again, I can only get 5.1 through the fuel tap with the tank vertical. My Owners Manual says 23 liters ("reserve 4 liters, about") which looks to convert to just over 6 US gallons. Ain't no way.

The later tank gives up some capacity to the internal pump/filter, but is longer at the front. What is the stated capacity of the later long tank?