1961 Fuel pump

[Matt 12861]

I've been reading everything I can on Vapor lock.   My '61 Deville has stopped twice this spring from vapor lock after only running ten minutes or so.  It has a stock carb, fuel pump, filter, etc.  It also has air conditioning so it has the fan shroud and return fuel line.    Last summer I drove it all over (500 miles) with no troubles at all.  Before that it was sitting for years not running.  I can't think of anything different between this year and last year.  I am thinking of putting an electric fuel pump inline at the tank and leaving the mechanical on in.  Can anyone that has done this before give me the brand/part number of what they used?
Thanks,
Matt Givler

[Gabe Davis]

I had some vapor lock issues and also wanted to be able to prime the fuel system after the car sat for a long time to reduce wear on the starter. On my '59 I put a Spectra Premium SP1251 rollervane fuel pump in near the tank.

https://ecat.spectrapremium.com/en/parts/SP1251

The SP1251 has the correct pressure and allows fuel to flow through when not running. It is quieter than the clicky-clacky pumps, being rotary. I also put in a check valve and a couple of T fittings to allow fuel to flow around the electric pump for additional flow.

I got those parts from NAPA. For '59 they are 5/16.

https://www.napaonline.com/en/p/NOE7306784

https://www.napaonline.com/en/p/NOE7302948


All of that is before the mechanical pump that I made no changes to.

For power I have a single pole double throw center off switch and a relay. The switch is prime-off-on. In the prime position the pump will run with the key on and engine not running. In the on position the key must be on and the oil pressure switch must show pressure for the fuel pump to run. The oil pressure feed drives the relay so if the engine stops the fuel pump will stop for safety.

When the switch is off it is as if the electric pump is not there and the mechanical pump runs as originally intended.

That setup along with using non ethanol gas and adding some VP Fuels Maddative octane booster have helped tremendously. And starting the engine from sitting is so much easier. I usually leave the pump off, crank until there is oil pressure, set the pump to prime and let the carb fill, start the engine and turn the pump off.

If I run into a situation where vapor lock is occurring simply flip the switch to on and cool fuel can be pushed up the line to the filter to the carb when needed and back the return line when not. The vast majority of the time though, the pump is off.

Hope that helps!

[Matt 12861]

Gabe: perfect!  that is exactly what I was hoping for.   I going to get the parts and give it a try.

[Gabe Davis]

Happy to help!

I put together a couple of diagrams to visually explain the fuel line and power routing.

Power



Fuel Lines

 

[Gabe Davis]

Ideally, there would be an inertia switch somewhere in the "on" circuit to kill the power when a collision was detected. The relay is a cheap way to do a similar cutoff but assumes the engine has stopped, which may not be the case in all collisions. Those collisions are a worse case scenario. The relay works fine in case you forget to flip the switch to "off" when parking. The power will stop any way when keyed off but, again, it adds a layer of safety.