Re: Electric fuel pump vs original mechanical fuel pump

Posted by HH56 On 2021/1/26 19:23:01
You will most likely get differing opinions but I think many have added a solenoid type pump near the tank primarily for use in priming the carb after the car has sat. The increased volatility of todays gasoline seems to be more prone to "boiling off" or evaporating from the carb on engines that have not been run for some period of time. Being able to fill the bowl before trying to start the engine does eliminate a lot of extra cranking.

Some have also had occasion to turn it on during a normal drive because of vapor lock conditions. The slight increase of pressure in the fuel line before the mechanical pump does seem to keep the dissolved gas bubbles in the fuel from expanding so readily to cause the vapor lock symptoms.

As long as the pump is on a switch so it can be turned off and is the solenoid type where the mechanical pump can pull fuel thru when the electric is off then IMO, needed or not, it is a bit of extra and inexpensive insurance. Airtex makes a low pressure solenoid type pump that closely matches the output pressure of the mechanical pump. Several have used model E 8902 on the early 40s cars. It is a 6v pump with 5/16 ports and an output of 2.5-4.5psi. With individual connection wires it can be configured for pos or neg ground.

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