Thread: Electric Fuel Pump - 101

Tweet

There has been a rash of posts concerning electric fuel pumps of late. We’ve discussed the “pros” and “cons” of both electric and stock mechanical units and while I’m a big fan of the stock units (especially on GM engines) I realize that from time-to-time, there are very valid reasons for installing an aftermarket electric unit – typically for space or clearance reasons.

One thing we have not talked a lot about (Jerry implied cost and a few key items as I recall) is how to correctly install an electric fuel pump. I’m a firm believer in braided stainless steel hose (3/8” minimum) and correct AN fittings – not barbed fitting with worm clamps – as I want to sleep well knowing the fuel delivery system will not be a safety issue on a car that I have worked on.

The electrical piece is the one most often overlooked. The worst (and very dangerous) way to install an electric fuel pump is to directly wire the pump to a switched source. Not only do most people use a wire that is too small and risk pump failure from drawing too much current, a direct link has no safety measures.

I like to use an “Electric Fuel Pump Safety Controller” device made by Revolution Electronics out of Cypress, California. This device provides a three second “on” time for fuel priming and thereafter will shut down if the engine is not running. They accomplish this by way of the tachometer lead from the distributor rather than an oil pressure sensor like many others do. This way you get a full three seconds of power to the fuel pump circuit without having to wait for the starter to crank up the oil pressure to 7PSI (most sensors) and more importantly, if the engine does not start you’re not supplying fuel under pressure to the carburetor. This is really important to hot rodders as we tend to let our cars sit for prolonged periods of time and while well intended, sometime without fuel preservative and the gas in the float bowl gets nasty and the needle sticks open. Ever seen gas pour out the carburetor when the float is stuck? I have and it scares me to death.

In addition to the Revolution component, I believe in relays for high current devices, like an electric fuel pump. I’ve drawn a little schematic of how this goes together (below). Key to remember is keep the Safety Controller and relay dry. On my 63 Nova, the battery is in the trunk so the relay is located there to minimize the #10 wire. The Safety Controller is under the dash, close to a switched source.

Hope someone finds this beneficial.

Regards,
Glenn