63 EM Stock vs Electric Fuel Pump

[TheCommish]

The person I got my car from was having vapor lock occasionally in hot weather, he was told to buy an electric fuel pump in it, and run them together. I question that as the problem, I'm looking for some idea's?

[terribleted]

That is not really a problem as long as the fuel pressure is not too high making the carbs flood over. It is a bit silly and redundant, and can make an issue if the mechanical fuel pump fails internally allowing the electric fuel pump to fill the engine up with fuel leaking into the oil. ( a stock pump can actually do this on its own with some internal failures). When installing an electric fuel pump (I like electric pumps myself) the stock fuel pump should be bypassed so there is no chance of a ruptured internal diaphragm allowing the fuel to pump into the engine. You should also install at least a inertia switch shut down the pump in a wreck and perhaps switch that shuts off the pump when the oil pressure is zero (engine not running)...safety items. It is pretty hot here in Atlanta and I have never had an issue with vapor lock. Fuel lines must be routed up so they do not touch hot engine parts on the way to and from the pump. It is possible, and an electric pump forcing fuel back to the engine from the tank would solve vapor lock issues.

[bbodie52]

General Motors did extensive testing of the Corvair during the development phase to ensure that they would operate successfully as designed in a wide range of temperature and weather conditions. Over the years the car was refined to help the Rochester carburetors to perform better in high temperature conditions. As emissions controls and smog pumps were introduced as mandated by federal and state governments, heat buildup became more of a problem. In 1967, Chevrolet added a small fuel return line between the mechanical fuel pump outlet and the gas tank. This return line allowed fuel to continue to move within the long fuel line from the gas tank, which effectively help the fluid in the line to remain cool enough to prevent vaporizing.

Your 1963 Corvair should not have a problem with vapor lock unless something in its configuration has changed. For example, there are thick plastic insulators sandwiched between gaskets at the base of each carburetor. These insulators help to prevent heat from the hot aluminum cylinder heads and intake manifold's from physically transferring into the aluminum carburetor bodies (which can cause a heat buildup to the point where the gasoline may vaporize in the small passages inside the carburetor body). Carburetor rebuild kits usually include a gasket for the base of the carburetor. However, the plastic insulators may become damaged or cracked during the removal process when the carburetors are going to be rebuilt. Some mechanics may decide to simply omit the insulator and install each carburetor using one gasket only. This is insufficient, but the problem that it causes may not be immediately noticed until the car is operated in hot temperatures. I would suggest checking each carburetor to ensure the presence of the required carburetor insulators, and if they are missing they should be replaced.

Carburetor Base Insulator and Gaskets.jpg (56.62 KiB) Viewed 599 times

http://www.corvair.com/user-cgi/catalog ... IN&page=56

You should also check the metal fuel line between the fuel pump inlet and the front of the engine compartment. Make sure that it has not shifted position where it is in physical contact with an adjacent metal component. Physical contact between the fuel line and the engine sheet metal for example, may allow enough heat to be conducted into the line to promote vapor lock.

You should also try to confirm that vapor lock has become a problem. Other heat related problems, such as an overheating, aging ignition coil, could cause a breakdown internally as the coil heats up. You should try to verify that you still have a good ignition spark at each spark plug when the engine becomes hot — especially if it starts to misfire. The problem may or may not be caused by a vapor lock condition.

While installing an electric fuel pump may resolve a vapor lock problem that has developed in your car, it is a relatively expensive and complex change that may not be necessary. The factory design of the fuel and ignition systems in the 1963 Corvair has been proven to be reliable for decades of operation in many thousands of Corvairs. I would suggest carefully checking the basic system before jumping ahead and trying to resolve the problem with a modification that includes electric fuel pump and associated safety switches.