Vapor lock!

[FuelCooler]

Here goes:

1. Unseasonally hot today (90 F)

2. Fresh fill up of 4.5 gallons of Shell premium (today)

3. Spirited ride home (22 miles)

4. Install new front brake pads (45 minutes)

5. Start bike to go for test ride (bike is still very warm)

6. Acts like its running out of gas..stalls.

7. Try again, fuel pump is coming on, but sounds weak.

8. Check for tank suck, swap all relays with each other, try starting again (re-read #6)

9. Take off my helmet to hear better, I hear fluid boiling under the tank!!

10. Key off, I remove the fuel line to check the petcock (electric) and the line is burping and spraying fuel out. Hmmmm...

11. Key on, petcock working fine.

12. Key off, reconnect fuel line.

13. Disconnect regulator fuel line (the tank return), more burping and spraying.

14. Key on and off (cycling the fuel pump) until I get decent flow at this side (pressure side).

15. Reconnect line and start. Everything fine!

16. Up and down the alley it runs fine. Sweet.

17. Decide to snug up the steering head bearings (45 minutes)

18. Suit up to go for ride.....sputtering out and stalling by the end of the alley.

 

I am going to let it cool for a couple hours and see if the cool evening temps fixes it. I believe I have been bitten by a high vapor pressure fuel (winter gas) on a summer like day. It ran fine all day yesterday at 80 F (128 miles on fresh Marathon premium). Either way, that Shell tankful is heading for the Montero!.

Boiling gas!

 

I will keep you posted.

Cheers,

Steve

[Guest ratchethack]

I think you nailed it, Steve.

 

As Todd at GuzziTech says, "It's a fuel-cooled motor."

 

By my experience, as long as you keep it running in hot weather, the FI recirc. circuit is for the most part a self-cooling system.

 

By my experience (Part II), after the motor's up to full operating temp in hot weather, 15-45 min. shut down is about right (depending on ambient) for enough "heat soak" to set up the dreaded VL.

 

Winter formula gas more susceptible to VL? Could be.

[Skeeve]

Winter formula gas more susceptible to VL? Could be.

 

Very likely. Of course, here in CA we have "winter fuel" all year round!

 

Just for insurance, folks w/ models prone to vapor lock might want to (loosely) wrap some aluminum foil around their fuel lines to act as a heat shield. Seems like a considerable portion of the heat leading to VL would be radiant heating from the cylinder heads, and a simple reflector would be effective.

 

Of course, for the added "bling" factor & convenience of never having to worry about corrosion, a little gold leaf on the lines would be even better!

 

Ride on!

[FuelCooler]

I think it was the gas.

 

I siphoned the tank as low as possible and added about a gallon of last years lawn mower gas (very little aromatics left in there!) and fired her up. Fine. Rode to the same Marathon station I used yesterday and put about 5 more miles on it. Now I will let it sit for 1/2 hr and check it out again. And again, until I am confident it will stay running.

12,000 miles since I have owned it and this is the first case of vapor lock I have had. I hope its fixed!

 

If you are interested, google the words 'alkylate vapor lock', there are some articles from this year about it. The alkylate is used in the summer and keeps the vapor pressure down, but is more $$.

 

Too be continued.......

[FuelCooler]

Vapor unlocked!

It is fine with the new gas. I rode some more today, about 90 miles at 85 F, and stopped for lunch (1/2 hr.).

Fixed!

Ah, the Northeast....

 

Oh, and thanks for the replies, guys.

 

Cheers,

Steve

[Steve G.]

Vapor unlocked!

It is fine with the new gas. I rode some more today, about 90 miles at 85 F, and stopped for lunch (1/2 hr.).

Fixed!

Ah, the Northeast....

 

Oh, and thanks for the replies, guys.

 

Cheers,

Steve

 

 

No, I think it was superheated fuel, not bad gas. The 'burping' you have done will do the trick for a while. But it will do it again if the heat/short term stopping conditions continue. This happened to me 3-4 times till I got totally pissed about the whole thing. I re-routed the fuel lines away from the back of the cylinders, and it hasn't done this heat-stall thing for 3 years.

Steve

[DeBenGuzzi]

yeah they make some fuel line insulation, I'm sure its not REAL fix but I bet it makes vapor lock much less likely and more infrequent, I've had that, also the pinging around 3k in slow traffic on a hot day <_>

its not bad tho, and now I have another bike if I need to let the goose cool.

[GuzziMoto]

Very likely. Of course, here in CA we have "winter fuel" all year round!

 

Just for insurance, folks w/ models prone to vapor lock might want to (loosely) wrap some aluminum foil around their fuel lines to act as a heat shield. Seems like a considerable portion of the heat leading to VL would be radiant heating from the cylinder heads, and a simple reflector would be effective.

 

Of course, for the added "bling" factor & convenience of never having to worry about corrosion, a little gold leaf on the lines would be even better!

 

Ride on!

You may have ethenol added to your fuel year round(or whatever emisions additive is the flavor of the month), but I would be suprised if you actually have winter gas at all. Don't confuse emissions additives with winter/summer gas formulas. For cold weather use the blend gas differently so that it will work in cold weather better. Basically it has elements that evaporate at lower temps(lower vapor pressure) to help the engine start and idle. Summer gas has the opposite.

[Guest ratchethack]

This got me thinkin' (and you know nothin' good's gonna come o' that). . .

 

Found some additional intelligence on this at The Oil Drum WRT Steve's experience, which sheds some light on it, explaining RVP (Reid Vapor Pressure), and also brings in another closely related aspect of this, the price of fuel. FWIW, I've found The Oil Drum site to be a reliable source on many oil and gasoline related topics.

 

One aspect of this I hadn't considered is the fact that in a FI system, the boiling point of the fuel is kept much higher by the pressure in the system than it is at ambient. In other words, a pressurized FI system dramatically raises the temp required to boil the fuel in the system (relative to a carbureted system) -- as long as the motor is running. So add to the fact that fuel line pressure drops to ambient when the motor is shut off, and the presence o' the radiant heat of the great walloping mass of the V11 motor just below the high-pressure fuel line and fuel pump, and you have the perfect recipe for VL -- especially with the much higher RVP of winter blended fuel at ambient pressure! (see below)

 

SEE NOTE on butane content of fuel at end of short article below.

 

A Primer on Gasoline Blending

 

Gasoline is composed of many different hydrocarbons. Crude oil enters a refinery, and is processed through various units before being blended into gasoline. A refinery may have a fluid catalytic cracker (FCC), an alkylate unit, and a reformer, each of which produces gasoline blending components. Alkylate gasoline, for example, is valuable because it has a very high octane, and can be used to produce high-octane (and higher value) blends. Light straight run gasoline is the least processed stream. It is cheap to produce, but it has a low octane. The person specifying the gasoline blends has to mix all of the components together to meet the product specifications.

 

There are two very important (although not the only) specifications that need to be met for each gasoline blend. The gasoline needs to have the proper octane, and it needs to have the proper Reid vapor pressure, or RVP. While the octane of a particular grade is constant throughout the year, the RVP spec changes as cooler weather sets in.

 

The RVP is the vapor pressure of the gasoline blend when the temperature is 100 degrees F. Normal atmospheric pressure varies, but is usually around 14.7 lbs per square inch (psi). Atmospheric pressure is caused by the weight of the air over our heads. If a liquid has a vapor pressure of greater than local atmospheric pressure, that liquid boils. For example, when you heat a pot of water, the vapor pressure increases until it reaches atmospheric pressure. At that point, the water begins to boil.

 

In the summer, when temperatures can exceed 100 degrees F in many locations, it is important that the RVP of gasoline is well below 14.7. Otherwise, it can pressure up your gas tanks and gas cans, and it can boil in open containers. Gas that is boiled off ends up in the atmosphere, and contributes to air pollution. Therefore, the EPA has declared that summer gasoline blends may not exceed 7.8 psi in some locations, and 9.0 psi in others.

 

A typical summer gasoline blend might consist of 40% FCC gas, 25% straight run gas, 15% alkylate, 18% reformate, and 2% butane. The RVP of the gasoline blend depends on how much of each component is in the blend, and what the RVP is of each component. Butane is a relatively inexpensive ingredient in gasoline, but it has the highest vapor pressure at around 52 psi.

 

In a gasoline blend, each component contributes a fraction to the overall RVP. In the case of butane, if there is 10% butane in the blend, it will contribute around 5.2 psi (10% of 52 psi) to the overall blend. (In reality, it is slightly more complicated than this, because some components interact with each other which can affect the expected RVP). This means that in the summer, the butane fraction must be very low in the gasoline, or the overall RVP of the blend will be too high. That is the primary difference between winter and summer gasoline blends.

 

Why Prices Fall in the Fall

 

Winter gasoline blends are phased in as the weather gets cooler. September 15th is the date of the first increase in RVP, and in some areas the allowed RVP eventually increases to 15 psi. This has two implications for gasoline prices every fall. First, as noted, butane is a cheaper blending component than most of the other ingredients. That makes fall and winter gasoline cheaper to produce. But butane is also abundant, so that means that gasoline supplies effectively increase as the RVP requirement increases. Not only that, but this all takes place after summer driving season, when demand typically falls off.

 

These factors normally combine each year to reduce gasoline prices in the fall (even in non-election years). The RVP is stepped back down to summer levels starting in the spring, and this usually causes prices to increase. But lest you think of buying cheap winter gasoline and storing it until spring or summer, remember that it will pressure up as the weather heats up, and the contained butane will start to vaporize out of the mix.

 

And that's why gasoline prices generally fall back in the fall, and spring forward in the spring.

 

LINK TO ORIGINAL SOURCE:

 

http://www.theoildrum.com/story/2006/9/13/234043/431

[Skeeve]

You may have ethenol added to your fuel year round(or whatever emisions additive is the flavor of the month), but I would be suprised if you actually have winter gas at all. Don't confuse emissions additives with winter/summer gas formulas. For cold weather use the blend gas differently so that it will work in cold weather better. Basically it has elements that evaporate at lower temps(lower vapor pressure) to help the engine start and idle. Summer gas has the opposite.

 

Yes, yes, I know all that. I was just making the observation that CA drivers have to live with the cr@p fuel economy year round, whereas most others don't have to for 6 months of the year. Closest place I can buy real gas is AZ, a measly 200 miles away... Chock full of the stuff that's not in CA gas any more; it smells different, like gas did back when I used to pump it in my first "real" job.

 

Glad I don't have to smell like it all the time anymore, but I still wish I could buy it. 15% lower fuel economy for 10% lower emissions seems like a fool's trade; you wind up burning 5% more gas w/ the same emissions to go the same distance! Idiot bureaucrats...

[jtucker]

I was experiencing this "vapor lock" issue on my bike as well. I started to suspect that the electronic petcock might be contributing to this problem, so while my bike was undergoing its rebuild, I had the electronic petcock replaced with manual.

 

My reasoning is this: Stop for lunch on a hot day, electronic petcock closes, sealing off the fuel lines. Fuel in those lines vaporizes, but the vapor has no place to go. I'm *hoping* that with the manual petcock left open, the lines can vent, and the problem will be solved.

 

Again, this is all speculation. It was easy to swap the petcock, so I figured it couldn't hurt to try. Time will tell if it helped at all.

 

__Jason

[FuelCooler]

My reasoning is this: Stop for lunch on a hot day, electronic petcock closes, sealing off the fuel lines. Fuel in those lines vaporizes, but the vapor has no place to go. I'm *hoping* that with the manual petcock left open, the lines can vent, and the problem will be solved.

 

__Jason

 

This sounds like a good idea! Looks like I will be ordering one tomorrow, just to be safe.

Thanks,

Steve

[al_roethlisberger]

I was experiencing this "vapor lock" issue on my bike as well. I started to suspect that the electronic petcock might be contributing to this problem, so while my bike was undergoing its rebuild, I had the electronic petcock replaced with manual.

 

My reasoning is this: Stop for lunch on a hot day, electronic petcock closes, sealing off the fuel lines. Fuel in those lines vaporizes, but the vapor has no place to go. I'm *hoping* that with the manual petcock left open, the lines can vent, and the problem will be solved.

 

Again, this is all speculation. It was easy to swap the petcock, so I figured it couldn't hurt to try. Time will tell if it helped at all.

 

__Jason

 

 

I never had the electric petcock, as most 2002+ bikes didn't, and many still experienced VL as did I many times.

 

I don't think the petcock has anything to do with it, although it has its own problems when the wires/connector start to fail

 

 

Al

[Steve G.]

I never had the electric petcock, as most 2002+ bikes didn't, and many still experienced VL as did I many times.

 

I don't think the petcock has anything to do with it, although it has its own problems when the wires/connector start to fail

 

 

Al

 

 

Agree totally!

Steve

[jtucker]

Yeah... I can definitely think of some cases where the petcock wouldn't matter, but figured it couldn't hurt to try. That automatic petcock bothered me from day 1 anyway, so I'm glad to be rid of it, in any case.

 

__Jason