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· It aint rocket science
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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
 

· It aint rocket science
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What is the boiling point of fuel Cap and is it higher or lower with ethanol compared to fuel of old. And is it affected by pressure.

Someone knew a lot about fuel from previous post reading and think it was you. Apologies if I got it mixed up.
 

· It aint rocket science
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I could see it happening. Carb equipped cars with their typical 4-5 psi fuel pressures were not immune to vapor lock. I believe back in the day there was more than one factory service campaign to reroute fuel lines for a no start/vapor lock problem.

The GW has 2 psi, throw in the possibility of a weak pump and it now might be 1 psi and if the big thick OEM fuel line has been replaced with a cheap lawn mower line anything is possible and more likely.:)

Lean engine, weak pump, drilled cap, ethanol and cheap line. Combined together it could be the perfect storm. Lot of ifs but you never know until you start to dig into it.
 

· It aint rocket science
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Back in the day some new vehicles had foil looking heat shielding from the factory in the engine compartment wrapped around the fuel lines.

My brain just kicked in on those old memories.;)
 

· It aint rocket science
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Yup, that was the beginning of the emission era and under hood temps really climbed. Thermostats went from the 180's to 190's and catalytic converters were introduced, IIRC the normal operating temp was 300 and an overheated one would glow red at maybe 500 degrees. Converters were around in 77 and were introduced with the advent of lead free fuel shortly before, lead in the fuel would plug them up. More than one cop started a roadside fire back then with the cruiser parked over some dry longer grass.:ROFL: Especially if the engine was running rich causing HIGHER converter temps.
 

· It aint rocket science
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Fuel pumps and alternators are the 1500's Achilles Heel, engine electronics are fairly robust with no known real problems.:)
 

· It aint rocket science
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I would settle for a simple digital fuel pressure gauge mounted right next to or combined with the owner installed volt meter.;)

From the forums when the fuel pumps go it is a slow and intermittent process, a gauge would give plenty warning and conclusively to replace ASAP. At $250 a pop you want to make sure the pump IS the problem.

From reading the forums it seems some think that because there is no shop manual specified fuel pump pressure that it does not exist.:? And if someone does not own a low pressure gauge they can't see it for themselves, I guess is where the confusion comes in.

A modern carburetor has to be fed fuel at a deigned for volume AND pressure.
 
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