Alcohol Gas and Vapor Lock

Dynaflash8 · September 28th, 2009

Since they have forciably introduced alcohol gas at all stations here in Florida, I've come upon a knotty problem. I'm looking for anybody out there who has solved it. My 1939 Buicks will occasionally vapor lock running along the highway with temperatures of 90 or so and up. After stopping for gas or any other reason, when the temperature gauge goes up to the top while stopped, they will start right up and within 100 feet simply run out of gas. I've installed an electric fuel pump in line with a switch. When the car starves, I switch on the electric fuel pump and within seconds, the gas picks up and off we go again.

This is a pain to say the least. So, I bought some race car insulation for the fuel lines, but it's going to look horrible, and I'm not sure it will solve the problem anyway. This is because (1) while the car is stopped, the gas starts to boil in the sedament bowl on top of the fuel pump and (2) the car starts right up and goes, which indicates there is gas forward of the fuel pump until it's used up. To me that means the boiling gas at the fuel pump is creating a vapor or vacuum.

I thought of wrapping the fuel pump in home fiberglas insulation, but sort of discarded that idea. My current thinking is to install a fuel pressure regulator and go strictly to the electric fuel pump; piping around the mechanical fuel pump so as not to destroy the authentic look. I've been warned that if I don't take the mechanical fuel pump out of the line, I risk the rubber diaphragm breaking and having the electric fuel pump put lots of gas into the crankcase to ruin the engine.

So, you've read all of this. Who else is having this problem? Have you done anything about it if you have? What did you come up with?

Dave@Moon · September 28th, 2009

My 1960 Buick had a tiny Stromberg carburetor on top of a Buick big block. When gas was reformulated (with a much lower boiling point) in 1996/7 I had to resort to using an electric fuel pump full-time. I also relocated the fuel line away from the motor, since it no longer had to approach the fuel pump (for which I simply made a loop of fuel line so it wouldn't pump air into the crankcase in case the diaphragm failed). That solved the problem.

In 1980-1983 I was in graduate school in Iowa, driving a 1960 Falcon. Virtually ALL gasoline in Iowa was already E10 by then, and probably has been ever since. My Falcon did exactly the same thing (stumble/stall) on restarts that you describe all summer long. It was an inconvenience to be sure, but one I learned to live with. I learned to let the car idle for 30 seconds (long enough to vapor lock) after starting, just until it started to stumble. I would then blip the throttle several times, upping the rpms enough to "get through" the stumbling. Whether it was the fan cooling the lines or the pump upping the pressure in them and itself, the car would run fine from that point on.

If your problems have only been an irritant, you might get away with adjusting your driving like I did in Iowa. If you do go the electric fuel pump route I would seriously consider a relocated fuel line to avoid engine heat. Fuel lines can boil just as well as fuel pumps.

Dynaflash8 · September 28th, 2009

Thanks. It's been driving me crazy and it's a shame. I've owned this car since 1963 and driven it at 98 degrees many times and this never happened before. I'd say it was the car, but it has happened on all three of my '39 Buicks. I don't understand your description of the loop. Please write me at FireballStr8@aol.com and try to explain it to me more. I'm mechanically as dumb as a post.

Dandy Dave · September 28th, 2009

One thing I have learned,.... If you have changed the fuel pump, and the replacment has plastic valves, they will swell up and stick in the cages making it difficult, or imposible for the pump to move fuel efficiantly. Dand Dave!

The Green Dragon · September 29th, 2009

I have had the same problem with my 1916 Peerless V-8. The vacuum tank is on the firewall and heats up and the carburator sits between the exhaust manifolds in the valley. On hot days it would be OK if I was moving down the road but when I stopped it would start perculating, missing and stall. I insulated the fuel lines which helped but didn't solve the problem. A friend told me that he used a product called Seafoam in his gas and solved his problem. I tried it this summer and it seemed to work, however with this global warming we had the coolest summer on record and I never got out on a really hot day.
The nice thing about Wisconsin is there are many country taverns that are great places to let the engine cool off at.

jrbartlett · September 29th, 2009

One of the tricks we used when driving vacuum-tank-equipped cars across Texas during the 1960s was to install an insulated heat shield around the vacuum tank itself, since the tanks are typically mounted on the wirewall above the exhaust manifolds. It helps.

Dynaflash8 · September 29th, 2009

QUOTE: A friend told me that he used a product called Seafoam in his gas and solved his problem. UNQUOTE

I had a 76 Lincoln that got water in the tank and Seafoam was worthless, but that was with real gas. Here's our plan. We're going to block both inlet and outlet on the fuel pump, install an adjustable fuel regulator between the current inlet and outlet lines formerly hooked to the fuel pump and run on the electric fuel pump all of the time. I'll set the regulator to 4 pounds like it's supposed to be and locate it under the fuel pump. AACA allows an electric fuel pump on pre-War cars for judging. That said, I don't know what you'd do on a 1946-53 Buick straight 8 and still be okay for judging. They are the same cars mechanically.

If the diaphragm in the mechanical fuel pump goes bad, that way it won't matter.

Dean_H. · September 30th, 2009

I think your plan will solve your problem.

I had some vapor lock issues on a 1960 Chevrolet work truck a couple years back. I'd used this truck for about twenty years with no problems, until the vapor locking started. It was pretty ugly, wouldn't start at the most inopportune moments. I even resorted to pouring my large soda drink on the fuel lines, on one occasion, which left me parched on a hot day. :-(

My fix was to add a thick gasket under the carb to disrupt heat transfer. And I slit a piece of rubber fuel line length wise and put it over the steel fuel line for insulating purposes. Small tie wraps hold it in place, doesn't look to obscene. These two modifications did the trick for me, haven't had any problems since.

Dynaflash8 · September 30th, 2009

Thanks Dean,
We've also thought about the rubber hose idea, but just didn't think it would provide enough insulation. In addition, the vacuum line runs along with the fuel line for most of the way from the fuel pump to the carburetor on thes old Buick straight eights. It would take a bigger rubber hose. So I bought some stuff from a race car supplier called "Cool Tube." but it is large and grotesque. Ha, another $50 down the drain, as it was special order at Advance Auto.

If I'm going to run the Sentimental Tour in Texas next year I need to get this problem solved, that's for sure, unless they use real gas in Texas.

rick60 · October 1st, 2009

As a former mechanic I would occasionally replace AC lines. GM cars had insulation material for AC lines that were routed near the exhaust pipes. They are made of a reflective foil type of material. I cut the hose and remove the insulation. These will slip nicely over fuel lines. They look professional and do a good job of insulating the fuel line. There must be a lot of these in salvage yards.