vapor lock

[Guest hoffman]

'02 LeMans, vapor lock in hot weather at 6,000ft altitude. Fuel pump located above left cylinder - gets HOT. '03 LeMans pump in gas tank? Is this pump location an option for '02 LeMans? Other solutions?

[Guest Oliver]

Hi Hoffmann,

 

I think when you say 2003 model, you actualy mean the Le Mans which is modified and sold today. Following MG -I words it should be the 2002 model.

 

Anyway ...

 

Officially there is no option available for the "old" Le Mans ... but ... due to the Moto Guzzi module system, it is easily possible to swap a lot of parts from one model to the other. On the other hand ... it is often expensive

 

I imagine that you will need, at least, a new tank (which is ~1200.- Euro - painted), a fuel pump, new wires for the pump, mounting brackets.

 

From my expirience you have to search for each single part in the new Le Mans parts catalog and the you have to order them seperately. There is no kit available.

 

I never heard before from "overheated" fuel pumps. If this is really the prob, I better would install a kind of heat shield between cylinder and fuel pump ... this solution would be much cheaper.

 

Just my two cents.

 

Greetings from Hamburg, Germany

[Guest Guest]

You might want to check the fuel line routing to isolate them from the heads as much as possible. My bike had one resting on the left head.

 

You should trash the charcoal cannister setup too if you haven't already done so to prevent vacuum in the tank. The tip over valve frequently doesn't work right, resulting in fuel starvation.

 

Good Luck!

[al_roethlisberger]

The suspected vapor-lock issues I have heard of seemed more prevalent on the 2000 V11 Sports, where one of the fuel-lines ran very close, and in some cases rested, upon one of the cylinders. The theory was that when the bike was shut off, without pressure, and no air/fuel-flow to cool the bike/fuel... the fuel would "boil" in that line. Upon trying to start the bike, the fuel-pump would attempt to pump "air"(fuel-vapor) instead of liquid-fuel, and hence the bike would not start.

 

The only on-the-spot fix was to let the bike sit for about 20-30 minutes and cool down. The long-term fix was to reroute and maybe shield the offending fuel-line.

 

On my 2002 LeMans, the fuel pump is not inside the tank, and is not above the left cylinder either. It is more accurately described as suspended below the frame, almost under the huge fuel-filter which is on top of the frame under the tank. The pump is "shielded" by a wrap of rubber, which I can only assume is to protect it from vibrations. It may provide some thermal protection, but who knows.

 

And the only fuel-lines that come near the heads seem far enough away to be OK. In the case of the fuel-supply from the tank, it passes within 2 or so inches of the head, but is covered with silver metal braiding. So, so far, it seems OK.

 

On the pressurized side of things, none of the hoses come close. note: The pressurized fuel-line *did* come within an inch of the right cylinder, but in light of my research into the vapor-lock reports, I thought it would be prudent to cut the length of this hose and shorten the loop, putting it far away from the head. BTW, this particular line was the pressurized fuel-return line to the tank, again on the right.

 

 

So far, knocking-on-wood, this arrangement hasn't proven to produce any vapor-lock, and yours is the first report I've heard on a new V11 LeMans.

 

But I would agree that building a quality heat-shield, perhaps from sheet aluminum, would be a good idea, if in fact the pump proved to be susceptible. In fact, if you fabricated a good solution, you could probably sell a few

 

But, taking care to check the routing of hoses should help. I'll keep an eye on mine when I ride it through the desert here in a month to Las Vegas. If it doesn't vapor-lock in the high-desert.... it never should!

 

The only other hose/cables that I've moved(other than some electrical re-routing) are the vent hose that used to go to my carbon-cannister(which is long-gone). I have it and the tip-over valve lashed to the frame now, so it always stays vertical. And that hose is a couple inches from the head, so I put a 3/8" 3-inch long heater-hose segment over it just for extra protection from melting. But I think that's overkill, and has no effect on issues like the vapor-lock. I also moved my enricher cable and tied it back from the right cylinder, as it was touching and starting to melt.

 

Just little nits I've found while working on various projects so far.

 

*thinking* I really need to re-route the pressurized fuel-supply that runs from left->right... the factory has it wedged under the air-box and the transmission... kinda tight, and that makes me nervous.

 

al

[al_roethlisberger]

...correction, after inspecting my LeMans tonight, it is apparent that the fuel-pump is technically above the left cylinder as noted in the original post. Although it is mostly under the frame, it is offset to the left side and consequently closer to the left head by a significant amount.

 

However, I believe that most of the previous vapor-lock issues seemed to be reported as related to hoses being too close, especially the left-side. I would inspect that first. All in all, if anyone ever really figures out the problem specifically, it would be great to know the cause.

 

That "heat shield" for the pump is still a good idea though

 

BTW, my old FJ had some heat-shield fabric wrapped around many of it's fuel and vaccum hoses. It too was air-cooled, and many of these hoses rested right on top of the head. So this shielding must have worked.

 

It was almost asbestos-like, with a foil covering and was a narrow sheet, sewn around the hoses. I assume this same material could be had if one looked. It wasn't the most attractive stuff, but it apparently worked!

 

 

al

[al_roethlisberger]

An interesting option/observation on this topic....

 

I know it hasn't come up in the last few months, but then again, we're all in pretty cool weather now

 

But as I was reading the "shop manual" request thread, someone posted a link to the following:

 

Sport Cycle Pacific Featured Guzzi Items

 

...and about half-way down is a very chunky ribbed-aluminum "Fuel Pump Mounting Clamp" accessory to replace the plain old black steel one we all have. This item is obviously made as a "dress up" item, but with the right modifications it might serve as a better heat-shield than the OEM clamp??

 

Now, who's to say if the aluminum might actually make it worse by conducting heat more thoroughly than the steel/rubber OEM clamp... but since these guys have already made this one, it might not be too hard to convince them to make a "full length" model that covers most of the pump and for someone to look into it.

 

Anyway, just a thought. I might contact them and see if it fits our V11s, and if so what their thoughts are on this type of application.

 

And of course, there's still that heat shielding for the fuel-line from the JC Whitney catalog that I've still got to get before Summer rolls around again

 

al

 

 

Reference topics:

 

Dealer investigation into "vapor lock" problem

 

Jason Tucker's "vapor lock" survey

[dlaing]

The fuel pump clamp looks so fine you could probably reroute the pump to a cooler place.

 

I have a theory that the stalling may be caused by the ECU overheating.

If anyone who is prone to this problem want to try and diagnose the problem, try carrying a can of aerosol air around. If the engine stalls from heat, try cooling down the ECU with the aerosol.

If that does not work try the fuel pump, or fuel lines, or fuel filter.

If my theory is correct, perhaps a heat sink could be added to the ECU.

[al_roethlisberger]

Well, I called the fella, Dave I think... at South Cycle Pacific, and he says that the current iteration of that clamp shown on their website will not fit our V11 bikes.

 

However, they have been looking at modifying it, and making more products to serve the community of newer V11 Guzzis. No details, but he just mentioned that there has been a lot of new interest this last year in the new bikes and accessories, so that's good news. So we'll have to check back and see what new products show up over time.

 

Regarding the clamp as a heat-shield question though, we both were concerned that the current design is very questionable for that application. But we agreed that if there were enough of a market demand to make a handful of a "shields" that might work, he would be interested in chatting about it, and their current clamp might make a good starting point.

 

We also agreed that there is significant uncertainty in the community about the exact cause of the "vapor lock" phenomena, however we also agreed that a "preventative kit" that sorta covered all the bases shielding the pump and supply line, would probably be popular as an accessory by many owners... as we all often buy all sorts of gadgets in this vein... at least just for fun, if not pure practicality

 

Anyway, I'm going to give this some thought. I'm also going to look into a water shield for the transmission breather, maybe out of aluminum sheet. Dunno though.

 

BTW, in regard to the ECU overheating... maybe. But you'd have to prove that to me, as my experience with the "vapor lock" issue last Summer was totally symptomatic of a fuel-supply issue, with the pump just "whirring" away trying to pump vapor instead of fuel. Then it cooled down, and it started fine. Plus we have to take into account where the greatest heat gradient is. That's certainly more likely inches from that left cylinder than under the seat over the transmission

 

Who knows for sure though. Every bike is different, and someone may have a flakey ECU that is very heat-sensitive, compounding the problem.

 

But I think the majority of folks seeing this issue have reported scenarios that seem to indicate that their pump and/or fuel supply line have become overheated after sitting in still air. I'm hoping that a "kit" of some sort... whether home-grown, or if someone makes one... will provide at least a little insurance by covering as many of the possible problem areas at once, even if we're not 100% certain which part specifically is the problem.

 

I'm going to continue to think about something for both the pump, and supply line.

 

al

[dlaing]

The ECU is definately a long shot. The impression I got was that people had tried heat shields unsuccessfully. Perhaps they were only shielding the pump....Or worse, insulating the pump....

[al_roethlisberger]

Or worse, insulating the pump....

 

True

 

al

[Guest wanie]

I've also experienced the whole vapour lock thing. Without going into the details of how, when, and where it occured, I thought I'd share a cure I think is working for now. I bent a piece of 24 gauge stainless steel sheet (4"x4" from Metal Supermarkets) to a loose half "u" shape to fit over the fuel pump. I covered the side facing the engine with heat reflective tape (Home Depot) and zip tied it to the fuel pump. As an additional fix (and to

look cool) I'm making a carbon fibre air scoop to direct air between the cylinders as well as an air extractor scoop to suck air out...the extractor has a small fan in it that runs on a timer and switch to cool the bike when I'm having my coffee after a hard run!

[Guest Jaap]

Could you take some pictures and post them please. Sounds like a "cool" mod.

[Guest wanie]

Jaap: For sure, just waiting to get my camera back from the repair shop, I dropped it

Wanie

[Guest gdockray]

A friend here in Vancouver with a 2001 V11 Sport is experiencing vapor lock. I wonder if a means of insulating the hose would be to use Stratoflex fluid hose fire sleeve shown in the link here:

 

http://www.sacskyranch.com/h_fire.htm

 

It's for aircraft flammable fluid hose applications that are located on the engine side of the firewall. The construction is an outer shield of red heat-resistant silicone rubber with a heat insulation material inside. Installation is to simply slip the sleeve over the tube & finish the ends with heat-resistant silicone seal.

 

Here in Vancouver BC it's about $10-12 a foot.

 

George

http://www3.telus.net/gdockray/my_t/

[docc]

I am wondering how one would differentiate "vapor lock" from, say, faulty relay? Both tend to cause the intermittent restart fault.

 

From the history on these bikes it's good practice to be sure the relays are upgraded to the Bosch units before launching into a misguided diagnosis.