GL 1500 Vapor Lock

Vapor lock is a possibility.

Some guys have written here previously that the fuel in their tank was literally boiling and could be seen bubbling away with the cap removed.

Why would one guys fuel boil and not everyone else. Likely answer is the engine is idling a little on the lean side. The tank is right above the exhaust collector box and a leaner running engine will skyrocket exhaust temps thus heating the tank more with no airflow as in a traffic situation.

And if you are one of the guys who has drilled a hole in the fuel cap that also might contribute to the problem.

If fuel acts like water, when raising pressure of water it also raises boiling point. If the tank is not doing its little pressure thing the boiling point may be decreased.

Do the cardboard test at idle.:coollep:

http://www.goldwingfacts.com/forums.../426066-1500-fuel-mixture-diagnosis-test.html

If you use a car/truck experiences these bikes can confound you. I have to remind myself at times there are some unique issues that would not be common to a car. The fact that the tank is right over the hot engine and not in the cool back of a car. The same can apply to fuel lines. The carbs are somewhat protected by the foam rubber baffle deal but still I have percolation on very hot days. With all that said my opinion is that more likely the fuel had a chance to cool while you were wrenching and in fact that is why its started. Some air in fuel filters and fuel lines that run high in the vehicle is probably normal in any loop that is higher than the carb inlet especially if the hoses other end is below the inlet at any point. Sort of the same as the banjo fitting on the 1200's brake system but air in a fuel system is not an issue.
The buzzing that was mentioned is normal and there are threads that talk about it also. It is the fuel cap venting excess tank pressure from the hot expanded gas.

Normally I would agree with Captain Midnight. No way, but if you think about it more??? In the new cars with the pump in the tank. (like the 1500's right?) In cars it just doesn't happen. The entire fuel line is under 20 or 30 PSI fuel pressure and the boiling point (vapor point) is too high for even the hottest weather.

The bike has several things working against it. First the tank is right over the engine so it gets lots of heat. Cars are nice and cool in the back.

Instead of 20 or 30 PSI fuel pressure like a car (that really raises the boiling point) the wing has only a little pressure.
Cars have most of the fuel line routed away from heat and then stainless line where heat is under the hood. The 1500 has most of the fuel lines exposed to engine heat as well as the carbs. (and tank as I said earlier) So given the hot day, sitting in stalled traffic, all the issues I listed above, I certainly wouldn't be too surprised. Now I have to put one of those disclaimers. Just my opinion.

The boiling point of gas can be as low as 85 or 90 degrees. That's one of the reasons they have summer and winter blend. Raise the vapor point for gas. In the old days the gas pumps at the station had the pump on the island and they would suck the fuel out of the tank below. (now there are under ground pumps and above ground dispensers but the term has stayed) Vapor lock was very common then as vacuum ;owners the boiling point just like pressure raises it. Can you remember in the old days the station owners hosing down the asphalt over the tank. It wasn't necessarily just to keep thing clean. He had to cool the area to be able to get the fuel sucked out of the ground. Yes ethanol boils even easier. Ever notice how quick an injury dries when alcohol is put on it? The little pressure that the tank hold helps some but it ain't much. I'm just guessing but I think it's like 1 5/8 degrees for every PSI of pressure but don't quote me on that number but that is the jest of it. So 3 or 4 PSI is no big deal(our bikes) then again cars with 30 PSI is significant. Remember vapor lock when the fuel pump was on the engine and it had to suck fuel the length of the car? (lowering the vapor point even lower) The only thing was they had no ethanol back then.

I can't help myself...

Some thoughts below only because a 1500's induction is nearly identical to a single carb conversion in basic operation.

PurplePirate said:

5. Bike Temp Guage was between the 50 to 60% range
6. Fans had been on for over an hour full blast.

Click to expand...

This seems fishy in itself. Having your gauge read mid-way yet having the fan run continuously doesn't sound right to me. I'd be checking the cooling system...

PurplePirate said:

7. Had just started moving was less than 2 miles from Traffic Jam.
8. Bike just quit, no stumble, no warnings one moment it had full
power next the tach dropped to zero.

Click to expand...

A single carb conversion that runs out of fuel will do this exact same thing. Ask me how I know....

PurplePirate said:

17. After that bike started immediately and there were no further
problems for the rest of my trip home which at that point was
around 500 miles.

Click to expand...

A single carb conversion that now has fuel will start-up just like this, ...as described.
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So, whether via vapor-lock or some other reason, I see similarities out of my own experience for the basics of what happened to your bike. Your carbs sure sound like they ran dry and then filled again. Being a singular event with no other instances, I'd have to say you probably had fuel go from liquid to vapor prior to hitting the carbs. Discount the heat issues, you obviously ran out of gas (which obviously you didn't)... So, what's left? Something choking both float needles at exactly the same time? I don't think so...
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OK - I'm really done now 'cause Darth Vader is somewhere near. I feel 'em closing-in..

...except for my first vehicle, a '79 Chevy Big 10. That thing would lock frequently. I was 15/16 and it was smarter than me back then. Left me stranded enough that I learned to fear it.

1/2 ton truck with 454. Stock except for side exit exhaust.

It would die instantly. No warning of any kind. Just died. 15 minutes later life was good again, ...every time.

I know. It's not a Goldwing. But that is my experience (my only experience) with a vapor-lock issue.

PS - I should add that I had a '84 Fiero; a 2M4 4-cylinder. First year. That was a throttle-body engine. 2.-something. I don't remember exactly. It had a recall due to the fuel line running too close to the exhaust manifold. I had done nothing about the recall and sold the car. The new owner did nothing either and the line melted catching the rear of the car on fire. I never had a fuel issue with it, meaning no vapor-lock. It was injected and the pressure was too high to allow for it to happen. If it were carbureted the problem would've been resolved prior to leaving the proving grounds... Raising the fuel pressure also raises the boiling point, but this is really a non-issue at 2-4 psi as this is not enough pressure to affect boiling temperature. The alcohol is more of a issue than pressure. All alcohol solvents evaporate faster than gasoline does. Ethanol is no different (even at 10% by volume).

The real answer would be to install a return line to the tank. Where to install the return line so that pressure is relieved and keeps the bowls filled would be like debating oil.

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The "cool-can" is real-deal problem solver. In the trunk is where I've used them.
Today, ...the ricers have replaced us old-school types that've used cool-cans with their fancy CO2 sprayers. Kids... Eghhh. What do they know about anything rear-wheel drive anyways. That in itself is old-school now-a-days. Absurd. I still can't believe I have a Civic (it's really Baby's car, as it stays with her. Ha!)...