Fuel System: Dual mechanical-electric fuel pump

[ken-renda]

While at a car show a person told me of a dual mechanical/electric fuel pump arrangement that is said to make a slow starting car fire up quicker without flooding and stater grinds far less. The electronic pump is used ONLY for starting and is controlled by a switch on the dash. It is turned on for a moment, prior to ignition, whereupon the car is started. It is as if the electric pump is a primer and is in the off position after car starts.. He was very pleased with it. Has any one heard of this and what do you think?. Ken, Deltaville, Va

[53commander]

Lots of people do this but its to help with vapor lock not to use for every start.

[Son O Lark]

It helps fill the carb without excessive cranking. (After your car sits for awhile modern gasoline tends to evaporate out of the carb)

[sweetolbob]

No could find but they may exist. Seems like the worst of both worlds, a mechanical pump that doesn't look original and an electric pump mounted up by the engine in a position that would make it difficult to draw fuel and probably not solve a vapor lock issue.

If they gave me one, I sell it and put an electric back by the tank and keep the mechanical, if I wanted the look. In the real world, I'd just put in the electric pump like I do on all my cars and block off the pump access.

Bob

[Mike Van Veghten]

Yea Bob.

Mike

[RadioRoy]

I think that it's most likely a miscommunication or a misunderstanding on the part of the car show person who talked to Ken. He's probably talking about an electric pump used in conjunction with the mechanical one to assist the mechanical pump, like many of us have done on our cars. Maybe his mechanic installed it and he did not fully understand the explanation from the mechanic.

The electric pump is usually mounted back by the gas tank and the mechanical pump sucks gas through the electric one when the electric one is turned off. When cold starting is required, or when vapor lock threatens, the driver turns on the electric pump and positively feeds the mechanical pump. Works great both for cold starts and vapor lock prevention.

[Son O Lark]

I think that it's most likely a miscommunication or a misunderstanding on the part of the car show person who talked to Ken. He's probably talking about an electric pump used in conjunction with the mechanical one to assist the mechanical pump, like many of us have done on our cars. Maybe his mechanic installed it and he did not fully understand the explanation from the mechanic .

That's the way I understood it. Two separate pumps.

[StudeRich]

That's the way I understood it. Two separate pumps.

I think that is it, nothing special at all, just the existing Mechanical Fuel Pump with an added near the Tank Electric Pump, as talked about here many times and many members are using.

The reason I know that is, there is no way a "Universal" Mechanical Pump could fit hundreds of Engines, certainly NOT a Studebaker.

As usual everyone has their own reasons for preferring different things, count me in the: "If it isn't broke, LEAVE IT ALONE Group".

[30seagrave]

Years ago I had a Ford F950 Super Duty fire engine, it had a factory installed switch to an electric fuel pump with the notation to hold for 5 seconds before starting, always made for very quick starts.

[ken-renda]

This all started with a comment that my R2 grinds too long before it starts and you have to be careful to avoid flooding the engine. In any case it sound like an electric pump, energized for a few seconds before starting engine might help. A friend with an R2 has the same issue. A question though, will the electric pump (installed at he tank) push gas through the mechanical pump up to the carburetor without damaging anything? Ken, Deltaville, Va

[64V-K7]

, will the electric pump (installed at he tank) push gas through the mechanical pump up to the carburetor without damaging anything? Ken, Deltaville, Va

Yes, any electric pump will push fuel through the mechanical, however only a vane type or a solenoid type can be used on a switch. If you choose the inline gearotor type, the mechanical pump won't be able to draw fuel through it after it's switched off. So the gearotor type is a primary pump only..

[SN-60]

This all started with a comment that my R2 grinds too long before it starts and you have to be careful to avoid flooding the engine. In any case it sound like an electric pump, energized for a few seconds before starting engine might help. A friend with an R2 has the same issue. A question though, will the electric pump (installed at he tank) push gas through the mechanical pump up to the carburetor without damaging anything? Ken, Deltaville, Va

At what position are You keeping the throttle at when You go to start that hot R2?

[jlmccuan]

Try a NC Hobbs switch (pressure activated switch) mounted at the carb inlet line set for 5psi. Gas line out of the tank to a T with one outlet to the electric pump the other bypassing through a check valve reconnecting on the pressure side of the electric pump with a T, then continuing to the engine as normal. The Hobbs switch is wired to the key switch and the electric pump. In operation, the ignition is turned on to start. If there is 5psi pressure remaining in the fuel line the electric pump doesn't engage. If, as it would be normally, there isn't 5psi, the electric pump is engaged until the mechanical pump can maintain 5psi. The mechanical switch doesn't have to pull through the pump as it bypasses around it. The electric pump doesn't pump back through the bypass because of the check valve.

[ken-renda]

At what position are You keeping the throttle at when You go to start that hot R2?

Have not had a problem with hot starts. For example a gas station visit - starts almost instantly; when left for longer periods, but still hot, will start -- but it might be a little longer. In any case, I don't press throttle until I know it will start. Cold starts often require pressing throttle 5 or 6 times, where upon it will start and often sputter, run rough, and stop. Starts instantly on shot of starting fluid, but that's not an acceptable solution. Myer rebuilt the carburetor so I'm certain it is OK. Ken, Deltaville, Va

[gordr]

Given that the quality of gasoline has changed, and not for the better as far as our cars are concerned, I think the only logical solution is to go to a full-time electric pump, and block off the mechanical. You could also install a momentary switch in the line to allow you to manually shut off the fuel pump before parking the car in a situation where percolation after a hot soak might be an issue. Shut the fuel pump down about a quarter-minute before stopping the engine, and less fuel will remain in the bowl to cause percolation issues. Hide the switch under the dash, and it also serves as an anti-theft device.

Any full-time electric fuel pump installation should also include a switch and/or relay intended to kill power to the pump if the engine quits, but the ignition remains on. As a safety feature.