Wasted Fuel - Right Side of V11 Sport/LeMans Tank

[al_roethlisberger]

So, for those of us that own V11 Sport based bikes such as the LeMans, Scura, RM.... and of course the Sport itself .... you may be aware(if not, you are now ) that due to the design of the tank, lack of a "balance tube", the spine frame, and our bikes being EFI versus gravity-fed carb'd(one petcock), the execution of the fuel injection loop causes the right side of the tank to retain fuel that the petcock, ergo the injection system, cannot get to....

 

This is at least true of the 2002 and earlier bikes without the in-tank fuel pump. I have no idea how the new bikes are plumbed internally to tank, so it may be an non-issue with them...

 

 

But for the older bikes that have an external fuel pump, the only current solution is to "slosh" the bike violently to the left while riding whence one begins to see the low fuel light begin to burn. However, this is just a brief respite, as the fuel pressure regulator, located where a right-hand side petcock normally would reside, is happily dumping its fuel outlet right back into the right "saddlebag"

 

 

So, if you've been following my adventures in the "relocated fuel pump" and "vapor lock" threads... you've seen that I've been trying to rig a "balance tube" for our tanks. Of course, this should seem simple enough, after all, motorcycle manufacturers have been doing this forever... right?

 

 

Unfortunately, due to the neato plastic tank, a lack of good places for a fuel return, and various other gotchas due to having EFI... it's actually been difficult to rig a kit that works in practice.

 

Recently I thought I had it licked, but because I wasn't getting enough fresh fuel from the tank, and "old" fuel from the EFI circuit back into the cool "pool" of tank fuel... I rapidly experienced vapor lock over about 70 degrees F once the engine area was heat-soaked. Not really a surprise, as I had suspected it might happen, but worth trying. Anyway, more on that in the Relocated Fuel Pump Thread if you are interested.

 

But that was "background" on the impetus of this post... here is the primary reason.

 

 

As I tinkered with this project, I realized that no one(that I know of) including myself, had really measured whether this was worth doing... that is, is there enough fuel actually trapped on the right-hand-side for all this effort??

 

OK OK, I know that sounds stupid, but keep in mind that half the things I do to(note: "to" not "for" ...as in, is necessary ) my bike are for pure tinkering's sake

 

 

So Friday night I decided to accurately measure how much fuel is actually "trapped" on that right side once the left is drained, which basically is equivalent to one's running out of gas.

 

Several of us have estimated the amount of trapped fuel from the stated capacity of the tank minus how much we filled-up, etc.... but I took a graduated cylinder to it last night, draining through my retrofitted right petcock and the results were:

 

110 ounces

 

Honestly, nearly a US GALLON! SHEESH!

 

That's a big deal, at least to me anyway. On a steady speed super-slab ride(which I hate, but does happen) that's a good 40+ miles. Around town, it's probably another good 10+ miles before the danger light looms

 

Now, perhaps in the real world, this might be a bit less, but even 20 or 30 more miles range can make all the difference.

 

So, I guess I'll soldier on to figure out how to get this "balance tube" thing to work. If I had found out that there were only 20 or 30 ounces of fuel available, I might have just said it wasn't worth it. But 100+ ounces... well, goodness.

 

So, I'm off to my local speed shop to look for more fittings(I have quite a collection now if anyone needs a spare ).

 

 

As an aside, while thinking about this and looking inside my tank with a flashlight... I noticed that the plastic tubing and "resin" covering the brass nipples that come up through the tank bottom for the vents was very very thin on one of them.... so thin I could see through it. This would be a very bad thing to eventually vibrate and wear through, or to hit with a fuel pump nozzle. I never stick the pump nozzle into my tank, but for anyone so inclined, this would be another good reason not to. If either one of these vent hosed got knicked, your fuel tank would instantly start dumping all of its fuel under the bike...

 

 

Anyway, just some interesting info... that's a lot of fuel put to waste trapped in the right side after all. A poor design IMHO, but then again maybe MG never initially thought or intended these bikes to be long distance machines??

 

Who knows

 

al

 

 

P.S.

 

Here is the thread on Wildguzzi

[al_roethlisberger]

So that first post was copied almost verbatim from my post a couple days ago on Wildguzzi.

 

The current status is that since I have removed my airbox, there is a nice flat area under the tank that could easily accept a fuel fitting for a return. I have since drilled the tank and installed a AN-6 bulkhead fitting, sealed it up, and it seems like it will work just fine.

 

I was concerned about the durability of the tank, and still am , but have found that the material seems very very durable, and is no thinner where I pierced it than where the stock petcocks are located Anyway, we'll see over time.

 

I'll be testing it for operation and integrity(leaks) today.

 

 

al

[guzzi323]

Al,

You are a brave man sir. I am also quite annoyed at that 'unobtainable' fuel but I'm not ready to follow you just yet. I have other plans for my bike, I'm not certain when I'll have the time required to deal with it but when the time comes I'll happily add my experiences to your own.

 

John

[al_roethlisberger]

....thanks John, yes... "brave or stupid" ... time will tell though

 

I figure if the tank is ruined(I don't think so though. At worst I believe I could plug the hole.) I can always buy another. It's not like they are unobtanium *shrug*

 

I'll be filling the tank tonight and leaving it on a stand in the driveway overnight. We'll see what happens

 

But yes, I do have my "fingers crossed"

 

al

[mik]

What, is the exact capacity in gallons of the LeMans fuel tank?

My reserve light came on and I pumped 3.5 gallons into the tank. I figured I had about one gallon in reserve......how wrong am I?

[al_roethlisberger]

The marketing says 5.5 gallons for a 2002 and earlier bikes. That might be correct, or close.

 

I know I just dumped a solid 5ish gallons from a jerry-can into a bone-dry tank for my leak test, and that was right up to the neck.

 

I can double check tomorrow.

 

For the 2003 specs, MG lists the following:

 

Fuel capacity: 5.46 gallons (20.7 liters)

Reserve: 1.32 gallons (5 liters)

 

But I have no idea what this means... that is, do they mean 1.32 of the 5.46 gallons is "reserve", or that there is an additional 1.32 gallons on top of the 5.46? I'm relatively certain it is the former though, as with the new internal fuel-pump, and the tank remaining about the same size... I can't see it GAINING another 1+ gallon in capacity

 

But in either case, I don't know what 1.32gallon "reserve" means on the newer bikes?? Anyone know? On my old FJ, I had an electric switch/petcock that I had to flip to get to the reserve once I hit "empty" on the fuel-gauge. Do the new(2003+) bikes have such a function? I'm very curious about this, and if the newer bikes avoid the "trapped fuel" issue via the internal pump and it's requisite plumbing.... hrmmm

 

 

As an aside, if I do manage to ruin my tank, I'll probably spring for the new tank with internal pump and just paint it

 

al

[Guest dkgross]

I've wonderded this myself...the only experiment I've ever done is this:

 

I waitied until the warning light went on (at about 110 miles)..Then, I went for a cruise back and forth on a street near me thats' about 3 miles long with a zillion gas stations. I think I put an extra 20 miles on, then got scared, because I didn't want to push the bike

 

the light was glowing yellow, and when I filled up, I got 4.1 gallons into it...so..did I still have ANOTHER gallon or so left in the tank???

 

I'm happy if I can get 120 miles or so before I have to get off and stretch the legs out...No Iron Butt for me.

[Gio]

With "every-day" riding, I usually see the low fuel light at around 200km at which point approx 15 litres is required (~38 mpg imperial)

 

I have run-out of gas once - and made a note that it needed a re-fill of 21.04 litres. Last Dec I almost ran out again (spluttered into the gas station) this time needing 19.99 litres to fill.

 

So I think that in round figures, of the 25 litre capacity, only around 20 to 21 is useable, leaving 4 to 5 litres in "reserve" which agrees with Al's measurement.

 

This also means that I have around 5 useable litres after the light goes on.

 

Gio

[belfastguzzi]

I'm very interested in your post, due to an experience last week. I was too afraid to post a stupid beginner's question about it (and I imagined it has probably been discussed lots before).

 

I set off on a 20 mile trip to deliver documents by a deadline. After getting onto the motorway, the bike started spluttering and hesitating. It wanted to stop but I just kept the throttle open hoping that forward momentum would continue. I was afraid that if I stopped to investigate, it wouldn't start again. It felt like fuel starvation, but the fuel warning light was not on. However it did start to glow after about another 10 miles.

 

I got the documents delivered and headed to a petrol station. The bike seemed to be ok after that.

 

I was wondering about the accuracy of the fuel light?

I was also wondering where exactly the sender is located in the tank?

From what you say, it sounds like the usefulness of the light could be messed up by the useless trapped fuel in the right side?

 

When the bike was cutting out and dieing it was on a long straight. It could be that when I got to corners that enough petrol was then redistributed to keep me going for another 15 miles.

 

This is a 2002 bike.

[al_roethlisberger]

I've wonderded this myself...the only experiment I've ever done is this:

 

I waitied until the warning light went on (at about 110 miles)..Then, I went for a cruise back and forth on a street near me thats' about 3 miles long with a zillion gas stations. I think I put an extra 20 miles on, then got scared, because I didn't want to push the bike

 

the light was glowing yellow, and when I filled up, I got 4.1 gallons into it...so..did I still have ANOTHER gallon or so left in the tank???

 

I'm happy if I can get 120 miles or so before I have to get off and stretch the legs out...No Iron Butt for me.

 

 

Yep Dave,

 

Since you have a 2002, you DID have an extra GALLON sitting on the right side, unused, with the fuel warning light glowing full-on <_>

 

At this point, the float/sensor on the left side would read empty(which the left side is), the bike would quit running, and on the right side would still be a nice pool of unavailable fuel.... as mentioned, nearly a gallon.

 

Of course you could just lean the bike left a bit to get some(but never all) of the fuel to slosh over(at which point your fuel light might dim a bit), and you could probably tool along for a few more minutes, but not very long. As the EFI circuit would quickly reisolate that gallon of fuel on the right side

 

 

And 120 miles before the fuel-light starts to glow seems pretty consistent for around town riding. That has been my experience.

 

I agree that every 150 or so miles, it's nice to get off and stretch and take in the scenery. But then again, when out on the open road... it's nice to know you have that extra mileage so you don't get stranded. I've seen more than a couple cases where the distance between gas stations was a wee bit further than what I felt comfortable pushing my luck upon

 

So I'd like to maximize the available mileage, especially if I am already carrying the fuel

 

So far the tank is holding tight, keep your fingers crossed for me

 

al

[mik]

Al, I think the tank on the 03 models is a little longer than it's predecessors. At least it looks that way to me . So, if my fuel light was on and I filled the tank with 3.5 gallons that must have meant that I had 1.5 gallons in reserve? I guess the only way to find out for sure is run out of fuel.

[al_roethlisberger]

Al, I think the tank on the 03 models is a little longer than it's predecessors. At least it looks that way to me . So, if my fuel light was on and I filled the tank with 3.5 gallons that must have meant that I had 1.5 gallons in reserve? I guess the only way to find out for sure is run out of fuel.

 

 

Hrmm, I don't know about that... could be, but the frame didn't change AFAIK, and there's not much room for a longer tank if not Maybe Mike Stewart will see this thread and can measure his 2000 versus 2003 tank.

 

I do know that the fairings on the 2003+ bikes were changed/shortened to alleviate some rider complaints regarding leg/knee-room, so this may give the illusion of a longer tank??

 

 

Based on your fueling measurement, it sounds like the total capacity of the 2003+ tank is similar to earlier ones. I just wonder why in the 2003+ specs, Guzzi is listing this 1.5 gallons as "reserve"? To list it as such, one has to assume that there is a way to get to that last bit. On 2003+ bikes, the question still remains whether or not the in-tank pump bikes have this wasted fuel problem or not.

 

Can anyone with a newer bike confirm how the 2003+ bikes handle this? It's sounding like, and I hope, that the new bikes have the warning light go full-on, meaning you have that last ~gallon left. Now we just wonder if at this point, if the 2003+ bikes can utilize that complete "reserve" unlike the earlier bikes.

 

al

[al_roethlisberger]

 

I was wondering about the accuracy of the fuel light?

 

Good question I have no idea, but mine consistently comes on at 120 miles(before any mods to the tank) for whatever that means. If you figure out your total average range, you can probably pretty closely guesstimate available range over time based on this.

 

Of course, once you've one this, the fuel-light is really redundant to just watching mileage

 

I was also wondering where exactly the sender is located in the tank?

 

Look under your bike on the left side, locate the petcock. Note the sensor/wire mounted to the tank directy in front of this petcock. This is the fuel level sensor.

 

From what you say, it sounds like the usefulness of the light could be messed up by the useless trapped fuel in the right side?

 

 

Well, not really It pretty consistently reads the fuel level for the left side of the tank, which is the "side that matters" since we can't draw fuel from the right side

 

When the bike was cutting out and dieing it was on a long straight. It could be that when I got to corners that enough petrol was then redistributed to keep me going for another 15 miles.

 

This is a 2002 bike.

 

Could be.... did it ever do this again? It could have been a number of things, but yes certainly could have been the fuel problem you describe as well. Sometimes it's hard to tell especially if an intermittent problem. Here's hoping it was just a low fuel issue

 

al

[al_roethlisberger]

Well, the question was posed regarding total tank capacity on the 2002 and earlier bikes. I'll actually go empty the tank and use a calibrated pump to get this more accurate later in the week, but I can confirm that my aforementioned jerry-can was full, and was a 5 US gallon can when I topped the tank out this weekend.

 

So far I think we can say that Guzzi was being a bit optimistic

 

al

[emry]

My gauge starts to glow around 120 to 140 miles depending on the right hand action. Normally takes about 4 gal to fill.