A few years ago I had replaced a fuel hose on my pit cart with nicopp metal line where neoprene had previously been used. At Norwalk during the Pontiac Nationals I'm experiencing fuel starvation. This is during a very hot ambient temperature, plus I'm on asphalt which is as hot as 165 degrees during the daytime.
All I have to do to get it running again is let the engine sit for 10 minutes, and it restarts, runs well, but drive is less than a mile and it shuts down again. This is with an air cooled engine, and gravity feed fuel. So the next year I reroute the fuel line, use neoprene line, and for years, I have zero problems ever since.
The question I pose. since there is no fuel pump, and the fuel is gravity fed, did it vapor lock? The fuel did boil in the lines and gravity was feeding it. I guess I need the correct term here so I can describe what phenomenon happened.
The pressure of atmospheric pressure wasn't enough to keep the fuel from evaporating when it reached the carburetor bowl, because the metal line absorbed so much heat. So how is this atmospheric pressure fed gravity system heating the fuel to such a temperature that the needle and seat can't handle the vaporized fuel in a normal manner? My inquiring mind needs the answer.........
Is it fuel boiling, or does vapor lock exist without a fuel pump?
Here's what I came up with for a definition of vapor lock, and gasoline boiling from the net:
Quote:
What happens when you have vapor lock?
Vapor lock happens when your fuel boils in your carburetor or your fuel line. Vaporized fuel creates back pressure in your fuel system and prevents gas from getting to your engine. It commonly occurs when a car has been idling or has been turned off and then back on. Mar 1, 2019
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Quote:
What happens when gas boils?
Image result for gasoline boiling definition
Bubbles of vaporized liquid (i.e., gas) form within the bulk liquid and then rise to the surface where they burst and release the gas. (At the boiling temperature the vapor inside a bubble has enough pressure to keep the bubble from collapsing.)
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So, did my fuel boil, causing vapor lock without a fuel pump?
Seems maybe this discussion is becoming absurd, in dissection of terminology, but maybe I'm wrong. It wouldn't be the first time.
I do know that changing that neoprene line to metal was detrimental. Changing it back, and rerouting it cured the problem.
Vapor lock is real, fuel boiling is real. If you don't think so ask someone who has raced an oval track Pontiac, I have, and it happens. I've taken second place while leading a race, because under a yellow flag while you sit idling on the track while they realign the field, then run a lap before they throw the green, you punch it. and the car falls flat, and you get passed by a ford. Second place sucks........
The night that it happened, in 1982, I didn't give careful consideration to which phenomenon I had experienced, because I really didn't care at the time. Maybe 40 years later, I should reflect upon what happened, or not......
Once the car was back up to speed, the engine, and fuel cooled off enough that it never ran out of fuel for the final 2 laps, but when it mattered, it cost me first place.
