50 comander vapor lock

[doubledaddy]

Does not look like an air leak. It boils only after it gets hot. the boiling is at the filter at the carb and continues for 15 to 30 min after the engine is shut off. There are no metal lines from the line below the engine to the carb, all rubber hoses. Also by taking the mechanical pump out of the line or cooling the pump stops the boiling and the pressure starts at around 6 psi cold and drops as it heats up. I found the heat shield behind the spare tire and installed it. This helped a little but did not stop it. I have a 2 gallon lawn mower gas tank I am going to install as a gravity feed. This will eliminate everything in the fuel system but the carb. If this works I will work back to the tank one piece at a time.

[t walgamuth]

Does not look like an air leak. It boils only after it gets hot. the boiling is at the filter at the carb and continues for 15 to 30 min after the engine is shut off. There are no metal lines from the line below the engine to the carb, all rubber hoses. Also by taking the mechanical pump out of the line or cooling the pump stops the boiling and the pressure starts at around 6 psi cold and drops as it heats up. I found the heat shield behind the spare tire and installed it. This helped a little but did not stop it. I have a 2 gallon lawn mower gas tank I am going to install as a gravity feed. This will eliminate everything in the fuel system but the carb. If this works I will work back to the tank one piece at a time.

YOur signature picture looks like the 51 two door commander my dad bought new while working at the factory. He said it would go 103 with the stock single exhaust and after adding a second exhaust it would go 106.

It was surf gray with concord blue wheels so grandpa could build him a special seat. It had the v8 with stick and od.

When I was about 8 or 9 mom was driving it into town from greene township on old 23. We stopped at a light and a fellow in a chevy pulled up in the left turn lane planning to pass mom on takeoff. Mom did not realize he was racing her and took off at here usual snappy pace. He was eating mom's dust and tried to pull behind and hooked his right front bumper in our left rear. Then he locked up his brakes and dragged both cars to a stop while his car slid sideways as it would be with the bumpers hooked.

Mom was pregnant with one of my younger sibs. I had my bunny in a box on the back floor as we were taking it to the 4-h fair. Mom cried a little but when the police man came he had nothing but nice words for her.

The chevy guy was properly embarrassed.

[karterfred88]

can you post some pictures of the carb, fuel lines and pumps? Maybe they will trigger some insight not already given??

[Dick Steinkamp]

can you post some pictures of the carb, fuel lines and pumps? Maybe they will trigger some insight not already given??

Also, if you can get a hold of one of those laser thermometers (a good one on sale now at Harbor Freight for $25.99) post some temps when the fuel is "boiling" at the pump, fuel filter, carb, etc....as well as the engine temp at various points.

[doubledaddy]

I noticed several comments about replacing hose with metal pipe. Does rubber hose have a higher tendency to boil gas? I have about a foot of hose into the fuel pump and about 2 feet to the carb.

[jg61hawk]

This month's Turning Wheels in Tech Tip says add Diesel Fuel to the tank.

[brokencookie]

I run a testing laboratory at an oil refinery. Gasoline composition varies quite a bit from season to season ( Thank you EPA). During the summer months the gasoline formulation tends to have more of the "light ends" which lowers the initial boiling point. This is primarily from the addition of butane. Butane is cheap and boosts octane so refiners add as much as they can during the EPA defined season.
Gasoline is not like water. Water is a pure substance that always boils @ 212 F ( at standard temperature and pressure). Gasoline is a mixture and it boils off 1 component at a time. During the summer you will find that it starts to boil around ambient temperature and as low as 70 F. It continues to boil off the lighter components until they are gone. So if you distill gasoline it starts to boil at very low temperatures and continues to boil until the heaviest components boil at about 437 F.
Adding diesel to the tank will not affect the IBP ( initial boiling point). It only serves raise the final boiling point (FBP). Raising the FPB ends up leaving a residue which coats the surfaces and helps protect from rust, etc.
Pressuring your gas tank effectively raises the IBP so that your gas does not boil in the tank. The higher the pressure, the higher the IBP. If your tank is not pressurized then your only solution is to isolate and insulate.



Sorry to be so long winded. Hope this helps.

Bruce