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Electric Fuel Pump

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Ironman View Drop Down
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    Posted: 12 Apr. 2018 at 2:19pm
Hello Everyone:
I am in the process of rebuilding my 68k mile L134 CJ2A and was thinking of going with an electric fuel pump in line before the manual fuel pump. Essentially piggy backing the manual pump with an electric assist. Has anyone ever done this? Will the manual fuel pump even allow the flow of fuel from the EFP? 
My reasoning for this is when i originally built the motor and it was running, sometimes when it was hot and i stopped the motor the fuel would actually boil in the manual fuel pump and if i were gone from the vehicle for say 10 minutes it essentially would vapor lock and i would have to crank it for a long time before the fuel could get to the carburetor and re prime the bowl. Or should I just block off and remove the manual pump on the block and go totally electric?  I apologize in advance if this topic has been discussed before. Thanks for all your help in advance too !!!!
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ggordon49 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ggordon49 Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr. 2018 at 2:37pm
Couple thoughts:
1.) Why is the fuel boiling? Many purist's will tell you 6V, mech. fuel pump is all you need... Work then, works now. No need for electric fuel pump unless you are converting to EFI.
2.) Here is a diagram of an example I took from my 1949 International manual. This was a factory option in 49 for vapor lock.

3.) Dont forget about saftey.... You will need some type of kill switch to shut off the EFP if you ever roll over Confused
4.) Keep this in mind: I believe carburetors can only handle something less than 8 MAX pressure?? 5 psi is often stated as spec for fuel pressure on old vehicles with carburetors, so a regulator may be required.





Edited by ggordon49 - 12 Apr. 2018 at 2:52pm
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tumbleweed View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tumbleweed Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr. 2018 at 4:12pm
Ironman,

I put in a low pressure electric fuel pump to resolve vapor lock issues on my 3A a couple of years ago. I put a switch under the dash so I can turn it on when necessary as well. Make sure that the electric pump is a flow thru so when you don't need it, the manual pump will still pump thru the electric pump. The electric pump does a great job when we are in the mountains of Colorado. I wish I didn't have to run an additional pump but I have never been able to resolve the VL issue and I have done a number of preventative features to try and fix the issue. Some guys never have a problem but for me the electric fuel pump did the trick. During the FCT in Colorado I saw guys pouring water on their mechanical fuel pump to cool things off and it worked great. Be sure and put a fuse in line and some type of switch to turn off and on. I hope I never roll over so I did not have a kill switch in the event that happens. If I did roll over the EFP would not be my first concern!

Hope this helps. Just my 2 cents worth.

Edited by tumbleweed - 12 Apr. 2018 at 4:20pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 64CJ5 Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr. 2018 at 4:15pm
After suffering vapor lock on our CJ5 during the Fall Colors Tour three years ago I installed an electric pump.  I put it in line between the tank and fuel pump.  No extra pipeing, no safety switch.  If we were to roll over the fuel tank would be up side down and the pump would be starved for fuel as the fuel pickup is on the bottom of the tank.
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Mark W. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark W. Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr. 2018 at 5:02pm
I know a bit about electric pumps having used them on 5-6 different vehicles. The first thing to know is you are nuts if you do not install a Oil pressure Safety switch in the power circuit. The way the safety switch works is when cranking the engine the power goes straight to the pump. As soon as you let off the Key (or starter button) the power switches to being routed through a pressure switch that will open (sh*t off the power) if the Oil Pressure drops below 5-7PSI this prevents the pump from running if the Needle/Seat valve in the carb is held open either due to something like a roll over or if debris were to get stuck in it AND the engine is no longer running.

You should also run a Pressure Regulator to make sure the Pump is delivering the  recommended pressure to the carb. With some of the smaller/cheaper pumps this is less of an issue as they only operate at low pressures.

The inlet on the Electric should be at or blow the pickup at the tank (electrics do not SUCK fuel well they are designed to PUSH fuel) The back of the Riser is a good place to mount the pump. Make sure the mount has some rubber vibration dampening as well as it is BEST to run flexable fuel line into and out of the Pump.

Its also a VERY good idea to run a fuel filter just prior to the pump. It can even be screwed directly into the pump in many cases.

In my own case CHUG will be running a Holley Red electric fuel pump to a Shut off valve (to allow filter service with fuel in the tank as the filter will be below the level of the tank) to a Summit Racing serviceable 40 micron filter then with the line running inside the frame rail to a Holley Pressure regulator set to 2.5lbs (the Weber DGV carb I am running likes that pressure) then on to the Carb. I have made a blocking plate to remove the mechanical pump from the engine (along with the push rod)

Not at all suited to a stock jeep but I thought I would explain how I have chosen to run my fuel supply system. 

Link to the Post where I show the Holley recommended wiring circuit for an electric pump.

https://www.thecj2apage.com/forums/uploads/6692/pressureswschamitic.jpg


Edited by Mark W. - 12 Apr. 2018 at 6:15pm
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Rick G View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rick G Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr. 2018 at 7:12pm
I just installed a low pressure (4psi) electric fuel pump inline with the manual pump. I have a switch to operate it only when I feel I need it.  I wired it to the ignition switch “on” position.  Works great.  I only use the electric pump about 1% of the time.  I’ve never had vapor lock, btw, even when I ran with just the manual pump.  I run my Jeep from 3600’ to 13000’ and never had any fuel delivery issues.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ironman Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr. 2018 at 8:23pm
Thanks to everyone who has responded to this thread. I have been schooled in the art of EFP !!! Now all I have to do is put all this knowledge to work. I will let everyone know how it works out when complete. Again thank each and every one of you for your help.
Ironman 
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