Thread: Vapor Lock, Copper for fuel line?

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I won't go into a long story, other than to say I am experiencing vapor lock.

Are many successful fixing that with an exlectric pump? I have tried putting cool tube around the line in the engine compartment down by the pump and back a ways.

I have also discovered that I am using copper line. (This is a 56 that I rebuilt some time ago). Is copper a bad idea?

What are your thoughts?

Yes, copper fuel line is a problem. Many will say they've gotten away with using it, but they did just that.........got away with it. It's especially a problem if the car is laid up for a while as copper is a catalyst for oxidation of the fuel, accelerating varnish formation.

As for your vapor locking, most often it's a matter of the mechanical pump being the culprit. Mounted to the block it acts as a heat sink. It is built to pump liquid not vapor, so if the fuel is heated too much coming to the pump, or in the pump itself, it vapor locks. An electric pump solves this because it is usually mounted to the chassis (or submerged in the tank depending on your configuration) away from engine heat (and hopefully exhaust heat). Also check the routing of your fuel as it passes the exhaust system. If it's too close it will pick up heat enroute to the pump, then the extra heat in the mechanical pump has a head start on hitting the fuel's vapor point, and then if your pump is in marginal condition it gets even worse.

When I had a six in my 55 I would always have a problem with vapor lock. Putting an electric fuel pump at the tank solved my problem. I would run on the mechanical pump until I had a vapor lock problem hit the switch for the electric and it would start up and run fine. Carlg

Replace your copper lines with steel before you burn your car down. Keep the rubber lines as short as possible.
It's a common misconception that vaporlock happens between the pump and the carb. Not so. Vaporlock happens between the tank and the pump. As the fuel is being pumped from the tank it goes to a slight vacuum which lowers the boiling point. A restricted line at the tank or a plugged pickup screen aggravate this situation. A car that doesn't have a history of vaporlock usually has a problem back there. Sometimes a lost heat shield will induce vaporlock. Recent exhaust work might also if the pipes are too close to the lines.
The fuel pump will pump some vapors but not enough to run the car. The only good pouring water on the line between the pump and carb does is it gives the other lines a chance to cool enough to stop the evaporation and the pump has something to pump.
A electric pump by the tank pressurises the whole line so it's not a problem. A electric pump at the motor probably won't do much good.

Get rid of the copper line. It has very little fatigue resistance to vibration and will crack. Use rubber line ONLY to connect 2 hard lines (about 2" max at each connection) and replace the rubber periodically.

What's wrong with copper fuel lines?
I watch 'American Hot Rod' on TV and Boydd's shop built with copper fuel lines, so it must be the right thing to do

If you use copper, make sure you always know where the fire station is

Jeff

Originally posted by techinspector1
Get rid of the copper line. It has very little fatigue resistance to vibration and will crack. Use rubber line ONLY to connect 2 hard lines (about 2" max at each connection) and replace the rubber periodically.

Well, it turned out my fuel line wasn't copper. From looking at it with not enough light, and it apparantly having overspray from a couple paint jobs over the past 23 years, it looked like it was dull copper.

I took it off, and found it was steel

So, I put it back on, and added some cool tube around it near the tranny cooler.

I have put on an electric pump. I'll see how it goes now with the vapor lock.

The comments about copper fuel lines are right on the money. Don't do it ! ! ! If they really did do that on a TV show, it's gonna cause problems somewhere down the line.

When I put the 351W in my '72 Bronco years ago, I came up with a bad vapor lock problem, caused by re-routed exhaust pipes. Solved it just the way you're trying - wrapped the fuel line with insulation, and put an electric fuel pump back by the tank. No more vapor lock. You'll be fine.

Lar.

At a place I used to work in Richardson, Texas, we had a guy "fix" his fuel line with a section of copper from the fuel pump to the carb. About two weeks later, I saw his big Ford Galaxy on the 10 o'clock news.....on fire. He said that he was driving along and the thing caught fire. The nearest house was 1/2 mile away (before cell phones) and he had to walk (run). The fire dept saved the tail lights and rear bumper.

Copper for fuel lines or brake lines is not a good idea, especially since steel lines are soooooo cheap.