6v. Fuel pump

[Mike36]

Going to install a 6v pos grnd fuel pump to prime carbs with on a 39 Dodge D11. Anybody have any tips or pictures for doing this? I have been told to have the pump lower than the gas tank. Is that correct? Thanks for any help. Hope you’re all staying well.

[Doug&Deb]

Do a search in the technical archive on this forum. Many members have done this.

[Sam Buchanan]

1 hour ago, Mike36 said:

Going to install a 6v pos grnd fuel pump to prime carbs with on a 39 Dodge D11. Anybody have any tips or pictures for doing this? I have been told to have the pump lower than the gas tank. Is that correct? Thanks for any help. Hope you’re all staying well.

 

Why not just ditch the mechanical pump and run electric all the time? Having dual systems just complicates things. Most pumps can be wired for either ground system.

 

Here is the full-time Carter pump I installed on my P-15, it is located just forward of the rear axle:

 

Edited July 29, 2020 by Sam Buchanan

[Mike36]

Thanks for the picture Sam, I will think about that.

[keithb7]

I hooked up a 6V pump hastily for testing and troubleshooting purposes.  It works just dandy mounted in a not-so-great position. Mounted in the rear engine bay, attached to the firewall , about where the firewall contacts the car frame. Mounted down low, but not as low as the fuel tank. Nor near the fuel tank. My 6V pump is placed after the stock type mechanical fuel pump.  It is controlled by a toggle switch on my dash. I flip it on when when I want it on. It easily pulls fuel from the tank, sucks it through the mechanical fuel pump and pushes it up to the carb bowl. How do I know this? I tested fuel line pressure near the bowl, with pump switched on, engine not running.  I am not running any type of fuel pressure regulator either. The pump makes about 3.5 PSI. So I did not bother to install a pressure regulator. 

 

My fuel system is currently set up, described as below. Surely not what is ideal, but it works great as it is:

Fuel tank--steel lines along car frame---flex hose to mechanical fuel pump mounted to engine-- steel line up from mechanical pump----Rubber hose to electric fuel pump---rubber hose to fuel filter---Rubber hose to steel line--steel line to carb bowl fitting. 

 

My plan is to remove the extra rubber lines currently in use. Use steel lines wherever I can. I plan to move the fuel pump to the rear of the car down near the tank. I will continue to use the stock mechanical fuel pump.  6V electric pump for back up, and priming the system after its been left sitting for long periods of time. I'll get to the work this coming winter. For now I am just driving and enjoying the car over the cruising season. My system is damned, but works just fine.  On a related note the vast majority of my engine starting problems disappeared when I switched to non-ethanol fuel. The temporary 6V pump helped me confirm that. Today, that 6V pump is barely getting any use.

Edited July 29, 2020 by keithb7

[1949 Wraith]

I install an electric fuel pump on my vintage vehicles, to prime the fuel bowls before starting on the cars that sit longer between rides. Airtex makes a unit that is 6 volt and in the 5-8 psi range and usually available at RockAuto.

I only prime for about 6 seconds so the higher psi is not really an issue. The units are meant to push the fuel not pull it so they should be located near the fuel tank. They come with a small filter,  but I place my normal fuel filter before the pump. I have not heard of issues where it needs to be below the tank but that might be people installing the pump as a pulling unit.

I have 5 of these units both 6 and 12 volt and not had any issues with them, reasonably priced at around $30 and supposed lifetime warranty. unfortunately the 6 volt is presently out of stock.

https://www.rockauto.com/en/moreinfo.php?pk=293409&jsn=3

Edited July 30, 2020 by 1949 Wraith

[Pete]

I run a 6v positive ground Airtex pump on my 1939 Plymouth. I use it for priming just like Wraith said. I use the 3 - 4 psi one, as that's the pressure these old cars want to see. Works very well. I use just a rebuilt NOS mechanical pump for almost all of my driving. Handles the steep mountain grades well with the Airtex off. I used to have a Carter electric pump, but I could not run just the mechanical pump on steep grades unless the Carter electric pump was switched on. It seemed to have a restriction in the flow when it was turned off that the pulse pump does not have.

 

I spoke to a tech support guy at Airtex not long ago. He was one of the rare ones that would tell you the truth, not the company line. He said that Airtex was bought by the company that owns Carter, and is in the process of discontinuing the Airtex pumps. He said that if you order an Airtex electric pulse pump you will likely receive a Carter pulse pump, and that Carter only makes one part number for both the 12v and 6v applications. He pretty much said those were crap. The Airtex pulse pumps currently listed on Amazon still use the old picture but are not the pump that I use. I ordered one and sent it back.

 

Pete

 

Edited July 30, 2020 by Pete

[Mike36]

On 7/29/2020 at 3:30 PM, keithb7 said:

I hooked up a 6V pump hastily for testing and troubleshooting purposes.  It works just dandy mounted in a not-so-great position. Mounted in the rear engine bay, attached to the firewall , about where the firewall contacts the car frame. Mounted down low, but not as low as the fuel tank. Nor near the fuel tank. My 6V pump is placed after the stock type mechanical fuel pump.  It is controlled by a toggle switch on my dash. I flip it on when when I want it on. It easily pulls fuel from the tank, sucks it through the mechanical fuel pump and pushes it up to the carb bowl. How do I know this? I tested fuel line pressure near the bowl, with pump switched on, engine not running.  I am not running any type of fuel pressure regulator either. The pump makes about 3.5 PSI. So I did not bother to install a pressure regulator. 

 

My fuel system is currently set up, described as below. Surely not what is ideal, but it works great as it is:

Fuel tank--steel lines along car frame---flex hose to mechanical fuel pump mounted to engine-- steel line up from mechanical pump----Rubber hose to electric fuel pump---rubber hose to fuel filter---Rubber hose to steel line--steel line to carb bowl fitting. 

 

My plan is to remove the extra rubber lines currently in use. Use steel lines wherever I can. I plan to move the fuel pump to the rear of the car down near the tank. I will continue to use the stock mechanical fuel pump.  6V electric pump for back up, and priming the system after its been left sitting for long periods of time. I'll get to the work this coming winter. For now I am just driving and enjoying the car over the cruising season. My system is damned, but works just fine.  On a related note the vast majority of my engine starting problems disappeared when I switched to non-ethanol fuel. The temporary 6V pump helped me confirm that. Today, that 6V pump is barely getting any use.

Thanks Keith, I appreciate the info.

[Sniper]

I just run the stock mechanical pump, never had an issue with empty fuel bowls but I try to drive her regularly, when I am not in the company truck working I drive my Plymouth. 

 

Problem is I put about 50k a year on the company truck and maybe 500 on the Plymouth, something not right there.