Electric fuel pump advice?

[drsfmd]

Hi all- 

I've owned my 51 Plymouth for about 23 years. I rebuilt the motor when I first acquired it, but it's otherwise original. This is the year it's finally getting restored.

It only gets driven a handful of times a year. and that leads to lots of cranking when trying to start it, as the fuel makes its way up from the tank. I currently have an original mechanical pump on the car, and I'd like to give it a little bit of help, by adding an electric pump. 

So, that leads me to a couple of questions... 

- Do I leave the original pump in place, and if so, do I place the electric pump before or after the mechanical pump? 
- Should I remove the original pump and fashion some sort of blank off plate or use that as a mounting point for an electric pump? 

- Is there somewhere I can tie into an electrical circuit so the pump runs automatically (the ignition perhaps?) or should I install a switch somewhere to turn the electric pump on and off? Unless it's a safety issue, I'd prefer to figure out a way for the pump to turn on and off automatically, so I don't need to remember to do it manually. 
- any particular 6v pump that is recommended by the community? 

thanks in advance! 

[allbizz49]

I'd say if you only drive it a handful of times. What's a few extra seconds of cranking? As long as your battery and starter are up to snuff, might not be worth the effort and money, although not a big deal, to install an electric pump. You could also pop the hood and shoot a little gas in the carb so it starts right away. If you are going to do an electric pump, put it close to the tank and feed the stock pump with it. Tie into your ignition for power. Pretty easy install. Good luck.

[Sam Buchanan]

51 minutes ago, drsfmd said:

- Do I leave the original pump in place, and if so, do I place the electric pump before or after the mechanical pump? 
- Should I remove the original pump and fashion some sort of blank off plate or use that as a mounting point for an electric pump? 

- Is there somewhere I can tie into an electrical circuit so the pump runs automatically (the ignition perhaps?) or should I install a switch somewhere to turn the electric pump on and off? Unless it's a safety issue, I'd prefer to figure out a way for the pump to turn on and off automatically, so I don't need to remember to do it manually. 
- any particular 6v pump that is recommended by the community? 

thanks in advance! 

 

Regular posters are no doubt tired of seeing me post about the electric pump on my P15 but I see this is your first post (several threads in the archives on this subject....the archives are your friend....  )

 

To address your questions in order:

 

#1; Your choice on whether to run two pumps, but if you have a reliable electric pump why would you want to keep the antique mechanical pump with its failure modes?

 

#2; That is what I did but not as a mounting point. See #4.

 

#3; If the electric pump is part time you need a switch. If it is the sole full-time pump power it off the ignition circuit. If you go full-time you might consider an inertia safety switch.

 

#4; I use a 6v Carter rotary pump located close to the fuel tank. There are other pumps available but the Carter seems to be a robust pump.

 

[blucarsdn]

There are a lot of opinions regarding the pros, cons of electric fuel pumps and/or mechanical, I'll fast forward to my experiences with electric pumps.

I always run a stock mechanical pump, can't beat them for trouble free operation. In this day and age you have to make sure the pump is unleaded friendly, not something that is old stock and been sitting on a shelf for many years.

I have a '36 Ford that I have owned for 71 years, I put an electric pump in the car shortly after I bought it.. The old Ford flathead pumps were famous for failings, usually out in the boonies. The pump is mounted close to the fuel tank, electric pumps push better than they pull.

I have a toggle switch mounted under the dash, if the car has been sitting for quite awhile I turn the pump on to pump fuel up to the carb, when the pump stops running I know I have fuel to the carb so I start the car.

I have a 39 Plym conv coupe that has an electric pump mounted close to the tank wired in the same fashion as the '36 Ford with one added feature. I have a yellow light wired into the circuit to alert me when the pump is on.

I have an Airex 6v pump #E8902  on my '36 Ford, have the same type on my '39 Plym, except it is 12v.

It is generally recommended that an oil pressure switch be wired into the circuit for an electric pump, the purpose being to kill the pump if  the motar stops. The problem with the pressure switch is that the pump can not be used to prime the carb when the vehicle has been sitting for awhile.

A good mechanical pump will pull fuel through a good electric pump and the electric pump will push through a mechanical pump with no damage to the pump.

I also run an electric pump in tandum with the mechanical pump on my boat.

[drsfmd]

Thanks Guys. 

Sam, I spent a bunch of time in the archives before registering, and I found a couple of posts about electric pumps, but not exactly the questions I was asking. The search function is... lacking (or maybe I just don't understand how this one works, but the Boolean logic I was using wasn't helping")

With regards to the old pump, I have no problem removing the mechanical fuel pump- would you suggest leaving it in place and bypassing it, or removing it and putting a blank off plate in place? I'm unclear from your earlier response (i offered two options, so I'm not clear on which you did). Did you tie into the ignition at the ignition switch, or elsewhere in the harness? 

Allbizz49- if it were a question of a few seconds of extra cranking, I wouldn't worry about it. When the car hasn't been started in weeks (or months, during the winter) it takes a *long* time for fuel to get to the carb. If it's only been a day or two, the car starts right up. 

[1949 Wraith]

If you are going to keep your mechanical pump and want to prime your carb I would use one of the Airtex units as they are a pulse pump and the mechanical will pull fuel through fine. I have a few of these on a couple of my 3 of my vehicles. If the vehicle has been sitting for a long time I throw the switch for 5 seconds then turn off before attempting to start the car. I figure it saves the starter from additional wear and a backup if the mechanical fails or have a vapor lock situation.

 

If you want to delete the mechanical I would use one of the Carter pumps as they are the rotary units and I think they are more robust as well. I would remove the mecahnical pump so there is no possibility of fuel contaminating your oil if your mechanical pump starts leaking into the block.

 

Both are best to be mounted near the tank with a fuel filter before the pump. Wire both to the ignition and place a switch inline if you go the primer route.

 

I think Airtex is going out of business as Rock Auto says the 6 volt Airtex I want is discontinued.

[capt den]

if my 54 windsor sits for 3 or 4 days it takes alot of cranking to start it. i learned on this forum that if i remove the wingnut on top of the air filter and pour a small amount of gas in there, it will go into the carb. and makes the car very easy to start. of course if you want an electric pump, then ignore this suggestion. i operate on the theory that the way the car was originally built often works just fine and is less prone to problems. i would like to have disc brakes but i am too old now to start that project. modern radials are also better in my opinion. either you way go with this you should have a fun car to drive.     capt den    

[Sam Buchanan]

1 hour ago, drsfmd said:

Thanks Guys. 

Sam, I spent a bunch of time in the archives before registering, and I found a couple of posts about electric pumps, but not exactly the questions I was asking. The search function is... lacking (or maybe I just don't understand how this one works, but the Boolean logic I was using wasn't helping")

With regards to the old pump, I have no problem removing the mechanical fuel pump- would you suggest leaving it in place and bypassing it, or removing it and putting a blank off plate in place? I'm unclear from your earlier response (i offered two options, so I'm not clear on which you did). Did you tie into the ignition at the ignition switch, or elsewhere in the harness? 

Allbizz49- if it were a question of a few seconds of extra cranking, I wouldn't worry about it. When the car hasn't been started in weeks (or months, during the winter) it takes a *long* time for fuel to get to the carb. If it's only been a day or two, the car starts right up. 

 

I like to search the archives using Google's site search function:

 

site: p15-d24 "electric fuel pump"

 

That search will bring up a bunch of threads.

 

Pumps are personal preferences and there won't be a consensus. I replaced the mechanical pump with a block-off plate.  The pump is powered via the ignition switch and also has a safety inertia switch (Ford) in the circuit:

 

 

Having said this, my Triumph TR6 still has the mechanical pump but the first time it gives any problems it is history.  ?

Interestingly that pump has a primer lever on it but there is usually enough tank head pressure to deem it unnecessary.

 

 

Edited February 8, 2021 by Sam Buchanan

[Pete]

Hey, Blue.

 

That's exactly the same setup I use on my '39 Plymouth, and I use it the same as you do. #E8902 Airtex 6v electric pump for brief priming if it's been sitting for a while or after heat soak. Turn if off and use mechanical pump for driving. I bought an NOS Mopar mechanical pump and had it rebuilt by Then & Now. Never had a problem with it.

 

Pete

 

[drsfmd]

Thanks all-

 

This is super helpful! 

Sam- what function does that inertia switch perform? 

[Sam Buchanan]

1 hour ago, drsfmd said:

Thanks all-

 

This is super helpful! 

Sam- what function does that inertia switch perform? 

 

It is intended to shut off the pump if a hard impact (crash) occurs but I have no idea if it would work as intended. The modern cars that use these switches undergo a lot of engineering and crash testing---the only engineering these switches can receive in our old cars is of the shade-tree variety......  ?

[DJK]

I also use the Carter pump as Sam did .Along with the inertia switch, I also have a toggle switch to turn off the pump while engine is running to drain carb of fuel to prevent difficult hot restarts. Works great.

[wagoneer]

I inherited an electric pump, and a failing mechanical pump. The electric pump worked well but somehow I still had issues. I think the bigger problem is the risk of too much fuel pressure and overwhelming the carburetor. I installed a new mechanical, and my Windsor runs fantastic on mechanical only. I still have the electric as a backup, but I installed a fuel pressure regulator that limits output to 6psi (max the B&B can handle), because I was flooding it with the mechanical + electric. 

 

[Sniper]

I ran out of gas at the post office yesterday.  After getting back with a gas can full of fuel it didn't take long for the mechanical pump to fill the carb's bowl.  12v fed to a 6v starter makes it spin fast, lol.