Installing an electric fuel pump as a booster pump

[Mike Self]

I know more than a few 02ers have switched to electric fuel pumps and blanked off the opening for the factory-supplied mechanical ones. 

 

My question:  I want to install an electric pump simply as a booster pump--controlled by a dash switch so I can use it to fill the carb's float chamber after the car has been sitting--historically my Weber will go dry if left for more than 4-5 days.  Then once the car has started, I can switch the electric pump off and rely on the mechanical one.  The electric pump would also serve as a backup in the (so far) unlikely event the mechanical pump fails (1 failure in 54 years).  

 

I know the electric pump must be mounted somewhere near the tank and appropriately wired; that's not a problem.   Will this work? 

 

TIA

mike

[dlacey]

Hey Mike, there are in -tank lift pumps that go together with another main pressure pump from the Jetronic era of early FI. My concern would be that most electric pumps have some form of non-return valve to stop fuel draining back to tank...would that restriction (even in fwd direction) interfere with the function of the original mechanical pump?? It won't have the "suck" to overcome the extra pump in the line?

Certainly agree with your concept, on my TR4A I can hand prime with a lever on the mechanical pump, and it really helps ensure a prompt start, rather than cranking the battery flat while the fuel comes up.

[visionaut]

Mike, I don’t think an inline electric pump will necessarily flow fuel when it’s powered off. As Dave mentioned, the mechanical pump might then be cut off from the fuel. Perhaps an in-tank pump might be able to provide a ‘pass thru’ mode…but I suspect not.

 

Tom

 

 

[tzei]

I would go with some sort of a hand primer. Change fittings to suit. One way valve might be a problem? Something like this:

Delphi Replacement Supply Pump Hand Primer (8mm): 9001-088A - Merlin Diesel

WWW.MERLINDIESEL.COM

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HAND PRIMER

 

Edited May 7, 2023 by tzei

[mccusername]

They also make fuel pump priming relays that automatically run the pump for a set number of seconds when the ignition is turned on, then turn the pump off. 

[Einspritz]

The Delphi squeeze pump is similar to an outboard motor priming pump used with an external 6 gallon tank.

 

Squeeze to prime, allows flow through, and return check valve.

 

Note though that these tend to fail after about 10 years in the sun and are a bit stiff when really cold.

[mgben]

The SU Fuel pumps and Facet style have check valves and allow flow through.

See this MGB Article. https://www.dbraun99.com/Dave DuBois/Back_up_Fuel_Pump.pdf

Most like to be mounted near the tank and push.  I ran wiring for one while my carpet was out, usage TBD, mine will be either mech or elec. 

[PhilC]

10 hours ago, visionaut said:

Mike, I don’t think an inline electric pump will necessarily flow fuel when it’s powered off. As Dave mentioned, the mechanical pump might then be cut off from the fuel. Perhaps an in-tank pump might be able to provide a ‘pass thru’ mode…but I suspect not.

 

Tom

 

 

+1

What about an in tank pump which is low pressure for carbs. I have literally, this morning, been fitting an in tank pump, although mine is for EFi.

I can’t see an issue if the pump was to then run constantly, effectively supplying fuel to the mech pump?

[jimk]

17 minutes ago, PhilC said:

+1

What about an in tank pump which is low pressure for carbs. I have literally, this morning, been fitting an in tank pump, although mine is for EFi.

I can’t see an issue if the pump was to then run constantly, effectively supplying fuel to the mech pump?

I have one of those pumps in the basement complete with fuel level sensor and electrical pigtail wiring that Mike can have.  Will bring to the MidAmerica02fest if wanted.

[Dick R]

Mike

I have pretty much the exact auxiliary fuel pump setup you described.  Three years ago, I installed an inexpensive electric pump near the gas tank using a very inconspicuous push button switch located under the dashboard just below the choke pull handle.  The switch is only activated when I hold it down – like a doorbell button.  These pumps are usually kind of loud and that’s a good thing in this case because the sound changes when the carb has been filled. I use it only to fill the carb after sitting for a few days. The engine will then kick over immediately. The normal mechanical pump continues to work like it always did.  The presence of the turned-off electric pump doesn’t seem to have any effect on the mechanical pump.  I got this pump on eBay for less than 20 bucks.

 

I installed the same setup on another old car I had years ago, and it did the same job reliably. 

[tech71]

20 minutes ago, Dick R said:

I installed the same setup on another old car I had years ago, and it did the same job reliably.

Does the trunk board fit down flush over it?

[Dick R]

Yes, both the highest point of the electric pump and the fuel filter are slightly below the level of the fuel tank top.  The trunk board fits normally.

[Son of Marty]

Mike the small cube Facet pumps will allow you to draw fuel through it when the pump is shut down and they will fit under the trunk boards. These pumps have a reputation of being unreliable but thats not as big a deal for a booster. Pegasus has what you need.

[Dick R]

Correction to my earlier post.  I purchased the Bravex fuel pump that I'm using on Amazon, not eBay.  The current price on Amazon is $18.

[Lorin]

The Pegasus Racing online catalogue has very detailed descriptions of all their Facet fuel pumps including which ones have no anti drain back valves allowing them to be used as an inline auxiliary pumps. 
 

Also, they are a great company to deal with. 
 

 

 

 

 

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Edited May 7, 2023 by Lorin