Fuel pump

[rhschnauss]

I would like to mount an electric fuel pump to prime the carburetor before starting the car. Who has successfully done this and where did you mount the pump? The facet pump I bought is a pass through type and I will only be energizing to prime the system.

[Barry Wolk]

Fix your fuel pump check valves and you won't have to alter your car unnecessarily. A fuel pump is just a bandaid fix and it can kill you in a crash if its on, for any reason. If you're going to do it anyway, ay least use a momentary contact switch.

[Milsteads Garage]

Any electric fuel pump requires being mounted near the tank to work correctly. I planned on doing this but found it easier and about the same cost effectiveness just to buy a rebuilt fuel pump from Arizona vintage parts and install it instead. I completely agree that an electric fuel pump will help a 430 or 462 in a later car but on a 368 it isn’t really needed.

[Mark Norris]

My car is fitted with an auxiliary electric fuel pump located on the left hand main frame just above the rear axle so placing it close to the gas tank. The switch is located under the dash on the same panel as the antenna and interior light selector switch. Its an addition many MkII owners have made and its got me home on at least one occasion.

It helps in two ways a) if your car is only occasionally driven (like most of them) then it helps prime the fuel suction line to the engine mounted mechanical fuel pump, and b) it's a backup in case of valve failure of the mech. fuel pump. Its no surprise that modern cars are not fitted with an engine mounted fuel pump ..its a foolish idea to risk compromising the engine oil in the case of a pump diaphragm failure and its a poor engineering solution to attempt to suck a volatile fluid a long distance under negative pressure (far better to push under positive pressure).

Yes you could make the switch momentary for crash reasons but there were millions of cars manufactured with a non-momentary power supplies to the fuel pump (ie. supply connected to a ignition on circuit). If momentary it would also be something of a hassle to hold on if using the electric pump for backup.

[rhschnauss]

I use my mark II rarely and am tired of running the battery down and Having to recharge it just to get the car started. My 61 imperial has a rattle electric pump that I energize for 30 seconds and it starts almost instantly. Obviously the rattle pump primes the system and makes it easy to start after sitting for a while. That is my intention with installing one on the mark ii.

[Roger Zimmermann]

When my Cadillacs from the fifties are not started for about a week, the carb is empty, fuel evaporated. Thanks to an electric fuel pump in serie, the starting process for my '56 Biarritz is reasonable. With the Brougham, I had to do some manipulation to let run the original electrical fuel pump (located in the tank) to fill up the carbs, allowing the engine to start.
When I still had my '56 de Ville, I unscrewed a side bolt to fill up some gas into the carb.
Evaporation is not a myth, it's reality.

[Barry Wolk]

Roger, if the float lowers from evaporation, does the fill valve not open? If the fill valve opens and the check valve in the pump is defective,will the fuel not seek its own level to match that of the tank? Would a working check valve not keep fuel in the fill pipe?

[Barry Wolk]

There's another check valve that people forget about. The accelerator pump has to overcome a spring-loaded check ball at the bottom to squirt fuel on start-up. The check valve can stand open from debris. Mine did that. Fuel just dripped into the manifold until the bowl level dropped and opened the float valve, opening the system to atmosphere and drained the pipe because of the bad check valve in the fuel pump. Yes, evaporation is real, but there can be alternative explanations for an empty fuel bowl.

[Barry Wolk]

https://markiiforum.com/pictures/HolleySup.pdf

[Roger Zimmermann]

Roger, if the float lowers from evaporation, does the fill valve not open? If the fill valve opens and the check valve in the pump is defective, will the fuel not seek its own level to match that of the tank? Would a working check valve not keep fuel in the fill pipe?

To be honest, I never opened the fuel pipes to see if there is still fuel or not. Anyway, on the Carter WCFB carbs, the inlet fuel is above the fuel level; I suppose all carbs are the same. With the float needle open your theory is that this opening is allowing the fuel to go back to the tank, unless the corresponding valve located in the fuel pump is blocking that back flow. However, I don't share this opinion because the float needle is not designed for that.
A splendid example is the 57-58 Brougham models with the immerged fuel pump into the tank. There is no mechanical fuel pump, therefore no intake/outlet valves near the engine. But those damn carbs are empty after a week! Remember that gasoline now is way more volatile than in the fifties or sixties; this is most probably one of the aspect which cannot be put aside...The fuel vapors can escape from the vent valve integrated into the carb. When I'm taking one of my older cars at home, they are stored into a one car garage. The next day, there is a strong gasoline smell. However, if I'm attempting to start the engine from one of those cars the next day, no problem, they start immediately.; there was not enough time for the fuel to totally evaporate.
All my old cars have/had carter carbs. I don't know if a car with a Rochester carb would act identically.
A leaking check valve from the accelerator pump can also be noticed with an hesitant acceleration.
Of course, I cannot do anything on the Brougham now as I sold it last November.
This is the reflect of what I observed during the years I owned the cars; I cannot pretend that it's the sole explanation.