'31 Buick fuel pump question

[Guest arbys]

I have a '31 Buick that developed a fuel pump problem last fall. I had the fuel pump rebuilt and was told by a lot of old car guys that I should also install an electric 6V pump. I'm looking for advise in installing the 6V pump. I figured to install it by the tank in series with the mechanical pump on the engine. I plan to install an on-off switch. Should I run the electric pump all the time or just when I need the boost?

[michaelod]

I think this may be a case of "if it ain't broke don't fix it". Is there a specific problem you are trying to resolve other than the fact that your fuel pump itself broke? These old fuel pumps can often fail as modern gasoline contains significant quantities of alcohol, which is not necessarily related to its ability to deliver the appropriate amount of gasoline. This issue can be taken care of during the rebuilding process rather easily.

Thanks,

[Guest tpbruce]

Hi, had the same issue. I installed an electric in series with the mechanical. Use the electric to start and then swith off and run on the mechanical. I found some really helpful info on this site but will need to dig it out and provide you with the info.

[Mark Shaw]

I wouldn't put an electric fuel pum on a 31 Buick. The manual choke on 31 Buicks is very effective in getting fuel into the carb for initial start up... and can be adjusted to keep enough fuel flowing until the engine warms up...

Later models like my 38 Special have automatic chokes that, quite frankly, need a little more help. My 38 had an inline electric pump on it when I bought it and it works well to prime the mechanical pump, and to help prevent vapor lock on hot days while driving at higher elevations....

[Fred Rawling]

I drove my 1935 90 series to Phoenix for the national meet in temperatures over 90 degrees and had no problem with vapor lock or fuel problems. It has the same engine as the 31 except for the configuration of the combustion chambers.

The mechanical fuel pump was rebuilt with neopreen diaphram and I did add a heat shield over the fuel line where it crosses under the bell housing.

It ran fine at 65 mph on the highway all day and we took a trip to Scotsdale around noon with 110 degree temperature. The car was fine but we were hot.

[Guest Fr Mike]

I have a '31 Buick with the original stock mechanical fuel pump and carburetor. My experience has been that it is important to clean and re-line the gas tank and replace the old fuel lines (because of layers of crud gradually deposited over the years, reducing the inside diameter and, thus, restricting, fuel flow. I also found that it is absolutely essential for the diaphragm in the stock pump to be replaced with one made of a rubber compound that resists modern fuel additives, and for the pump & parts to be precisely and carefully adjusted. After much grief, I did these things and the old girl runs like a young one!

There is also another problem. I live in north-east Wisconsin, but the summers here can be very humid and 90+ degrees. My Buick has been having frequent warm weather vapor-lock problems--despite shields-- on unleaded RFG modern fuel, which vaporizes at a higher temerature than the old stuff. I installed an electric fuel pump to help out, but to no avail. I am now trying out a special gear driven electric fuel pump that is supposed to pump alcohol and that has been tested out to overcome the the problem of only vapor getting to the carburetor (Fifth Avenue Internet Garage). I have just finished plumbing it up and have found 2 problemswhich I will take care of when the weather warms up: I need a pressure regulator as the mechanical pump pressure makes an oozing leak around my stock fuel pump cleanout bowl gasket, and it is not a flow-through electric pump, so that I will need to install a bypass for when I don't want to use it.

I was advised by Randy at Fifth Ave. that under high risk vapor lock conditions, the pump needs to be running full time.

Edited February 17, 2010 by Fr Mike (see edit history)

[Janousek]

I also have a 31' that has an electric pump on it. It's wired to the ignition switch and is on at all times. It's positioned right in the middle of the car and a regulator is used at the carb. It was like this when I bought it and my grandfather did it in the 80's. I'm in the process of overhauling the engine and I will rebuild the pump with a new kit and put the electric pump on a toggle to use as needed. I can say that a hot day in michigan usually vapor locks the fuel on buicks from 40's to 50's. Not a guess, something I've experienced with her grandpa's cars. Just a flip of the toggle and your no longer surging or bucking.