Re: 6 Volt Electric Fuel Pump

Posted by HH56 On 2020/11/20 11:55:34
Many of us run an electric fuel pump mounted near the tank that can be switched on and off as needed. When the car has sat for awhile, a few seconds running the electric does help in replacing fuel that has evaporated or percolated in getting thru the pump and into the carb without a lot of cranking time. A secondary benefit is turning it on during vapor lock situations will place the suction line under a small amount of pressure which can help that issue. Modern gas is quite volatile and it has been suggested that vapor lock actually occurs in the suction side of the pump where the reduced pressure will allow the volatile bubbles to more easily escape and form a large air lock which the mechanical pump finds difficult to pull thru.

There are two type pumps. For the most part rotary pumps are quiet but mechanical pumps sometimes find it difficult to pull fuel thru them. Usually a check valve and bypass plumbing around the rotary pump is needed so the stock pump can pull fuel. Carter makes a 6v unit that some have used. A solenoid type pump has valves similar to what is already in the mechanical pump and when that style is turned off the mechanical pumps can pull fuel thru with only a minimal amount more effort. As long as the electric pump has pressure output suitable for the situation there is not much danger in overpowering the carb float valve. If you are really concerned then a pressure regulator could be added but many of the inexpensive regulators do not really do much good at such low pressures.

Airtex makes a couple of solenoid style pumps suitable for our use. Both are 6v, can be wired for positive or negative ground and sized for 5/16 line. They do have a small filter attached and both will install with minimal effort. Because the small pump filter is attached many add a larger capacity filter which has a removable element that can be serviced in the line before the pump so it traps debris from the tank before the one that comes with the pump.

The E8011 has an output of 5-8 psi and when mounted near the tank the line length and fuel being pushed thru the mechanical pump and any optional filters is usually enough to lower the pressure at the carb to an amount almost equal to what the mechanical pump would normally output. The E8902 has a lower output at 2.5 - 4.5 psi and could also be used if you wanted one that more closely matches the mechanical pump. It would be the better choice if the the mechanical pump was removed or if the standard screen mesh in the pump is the only filter and there are no fine pore filters such as the ceramic option Packard offered. Amazon sells the Airtex brand as does many parts stores.

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