EFI gas sending unit for a '73 Charger?

Triple Black 73

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I'm done with the Charger running rich, running lean, and generally running like poop. So, I'm converting to a Holley Sniper EFI system.

My question is the sending unit. I currently have a 7/16 unit with no return. I need a 3/8" with a return. Does anyone make an EFI sending unit with an in-tank pump? If not, does anyone make a sending unit with a 3/8" return?
 

PurpleBeeper

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I run carburetors, but I "think" you cut a big hole in your tank to install the high pressure fuel pump & leave your stock sending unit in place....for the gas gage only....you don't pull fuel through it any more and just plug off the fuel line.
 

bhemi

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Purple Beeper is correct, Sending unit has nothing to do with it. Sending units are just a float and electrical circuit with a variable resistor based on tank level. If you have an in tank pump (not necessary but quieter) you need fuel out and a return line with fuel back in. On another project I am running an external Weldon pump pushing fuel to a Hilborn EFI on a nailhead, then excess fuel goes back to the tank. Other than connections I suggest hard lines.
 

Triple Black 73

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Great ideas and thanks for pointing me in the right direction. This in-tank pump (link below) would be prefect, but it's pricey and would require drilling a massive huge hole in my shiny stainless steel gas tank. I'm not sure I'm willing to do that right away, but that could be the long term goal.

http://www.tanksinc.com/index.cfm/p...ct_id=227/category_id=61/mode=prod/prd227.htm

I'm thinking I'll use an external pump, swapping in an OEM style 3/8 sending unit with a return line then using a 3/8 to 1/4 reducer for the last few inches of the return feed. Sure, it's not the best solution but it should work OK. Right?
 
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70chall440

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I have installed 2 Tanks Inc. tanks and done one modification on an existing tank. The one thing you need to keep in mind is that just punching a big hole into the tank and installing a pump may work but is not usually the best way unless you install some Hydramat or some other tank insert to pull up and hold any fuel. EFI system (pumps) do not like to run dry and can burn out if that happens as a result of a low fuel level or during cornering, braking, and/or accelerating. EFI tanks are baffled and have a little area where the pump sits that will typically have fuel in most conditions. Just something to be aware of as you go through this. When I put EFI on my 70 Challenger I thought about using my existing tank but at the end of the day, it was much easier and better to purchase a new EFI ready tank. On my Cuda, I cut the tank apart and installed baffles.
 

Triple Black 73

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I have installed 2 Tanks Inc. tanks and done one modification on an existing tank. The one thing you need to keep in mind is that just punching a big hole into the tank and installing a pump may work but is not usually the best way unless you install some Hydramat or some other tank insert to pull up and hold any fuel. EFI system (pumps) do not like to run dry and can burn out if that happens as a result of a low fuel level or during cornering, braking, and/or accelerating. EFI tanks are baffled and have a little area where the pump sits that will typically have fuel in most conditions. Just something to be aware of as you go through this. When I put EFI on my 70 Challenger I thought about using my existing tank but at the end of the day, it was much easier and better to purchase a new EFI ready tank. On my Cuda, I cut the tank apart and installed baffles.

You're spot on about baffling and the pump running dry. I heard a good EFI tank will also have a sump the pump sits in which is an inch or two below the sending unit. I haven't seen a good off the shelf EFI tank for a '71-73 Charger and I don't even want to know what a custom made tank would cost (I might find a way to buy it, lol). Maybe in a few years I'll learn to TIG weld a custom aluminium one.

So after I weighed my options and to keep this project somewhat restrained (it's already over 2 grand!) I've created this plan:

Screenshot from 2018-12-05 11-10-59.png


The plan will be to get an OEM sending unit with 3/8 and 1/4 lines. I'll cut off the barbs to put on 6an hard line compression fittings. The 4 inches of 1/4 return line shouldn't be that big of an issue. I'll then run a line to the filters and a pump mounted on the frame rail, then up to the throttle body with 3/8 line brackets along the way. I also found out I'll need to remove the kickdown rod and switch to a cable system and brackets.

Parts list for anyone curious:

https://www.summitracing.com/parts/ear-at165006erl
https://www.summitracing.com/parts/ear-at165064erl
https://www.summitracing.com/parts/msd-8985
https://www.summitracing.com/parts/hly-526-7
https://www.summitracing.com/parts/sne-550-511

https://www.ebay.com/itm/STAINLESS-...E-AND-BRACKET-KIT-6054-6055-6056/253831656274
https://www.ebay.com/itm/10Pcs-lot-...apter-for-3-8-Oil-Fuel-Hose-Line/153128864276
https://www.ebay.com/itm/Plymouth-M...B-Body-New-Sending-Unit-3-8-Line/253281197236

Note: I found other sending units for less, but this one has 90 degrees bends on both lines. This should help with routing the fuel lines away from the exhaust.
 
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andyf

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I highly recommend that you just buy a new tank with an internal pump. That will be the easiest approach for you. If you want to roll your own then you'll most likely need to take it to a pro and have the tank modified for the pump. Here is a picture of what we did with the tank on my '65 Coronet.

Notice that the sending unit was not modified and it has nothing to do with the EFI fuel pump.
DSC_1084 (Large).JPG
 

Triple Black 73

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I highly recommend that you just buy a new tank with an internal pump. That will be the easiest approach for you. If you want to roll your own then you'll most likely need to take it to a pro and have the tank modified for the pump. Here is a picture of what we did with the tank on my '65 Coronet.

Notice that the sending unit was not modified and it has nothing to do with the EFI fuel pump.
View attachment 688408

That's slick looking. I think I'll put the pump in the tank because:
  1. There isn't enough room to tap into the sending unit because of the exhaust.
  2. There isn't enough room to mount the pump below the tank on a plate mounted to the tank strap hanger because of the Hellwig rear sway bar.
  3. I don't want to mount the fuel pump on the frame rail a quarter mile from the tank.
  4. There's less noise when the pump is in the tank.
The shelf would need to be welded in on the left side of the tank because the sending unit is on right side and vent tubes are in the middle. I can mount a filter/regulator high up on a plate in the middle of the tank between the tank strap bolt. I can then run a return line back to the tank and a single line to the engine bay.

The lay out will look like this:

Screenshot from 2018-12-08 16-21-55.png


Here's the parts list:

https://www.summitracing.com/parts/sne-19-360
https://www.summitracing.com/parts/sum-220996
https://www.summitracing.com/parts/hly-162-550
https://www.summitracing.com/parts/sum-250890b
https://www.summitracing.com/parts/hly-162-574
https://www.summitracing.com/parts/sum-250687b
https://www.summitracing.com/parts/ear-at981666erl
https://www.summitracing.com/parts/ear-at593204erl
https://www.summitracing.com/parts/ear-at592906erl

Edit: Another design change. This time I plan to use a Holley 19-360 with a built in regulator, no return, and PTFE braided stainless steel hose that is ethanol safe. The filter will be mounted somewhere on the frame rail or engine bay. I don't know yet.

Thanks!
 
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Triple Black 73

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I just remembered I still have the original steel tank in Alabama. I don't know how I forgot about it. I can modify, clean, and paint that tank then sell the stainless steel tank.
 
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andyf

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I had some blanks cut out on the laser and then bent to use on my tank. This approach works but it requires a lot of skill. I had to do it this way since an EFI tank wasn't available for my car. I highly recommend just buying a new tank if one is available for your car. If you want to modify your own tank then you might copy what I did.
AR385c (Medium).JPG
AR385d (Medium).JPG
AR385e (Medium).JPG
 

Triple Black 73

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I had some blanks cut out on the laser and then bent to use on my tank. This approach works but it requires a lot of skill. I had to do it this way since an EFI tank wasn't available for my car. I highly recommend just buying a new tank if one is available for your car. If you want to modify your own tank then you might copy what I did.
View attachment 688479 View attachment 688480 View attachment 688481

Thanks for the pic. Did you TIG weld it? The weld looks nice with good penetration.

Even if there were an EFI tank is available I don't have the budget for an in-tank pump and an EFI tank right now.

I think I'll use your pictures as a guide to modify the old tank. I'll then sell the stainless one and put a proper EFI tank on the BIG LIST. My dad can help me with the fabrication. He has 40+ years doing body work. He even repaired the tank on his '59 Olds a few year ago by brazing in a piece of plate to it. Not sure what lead to it. My dad doesn't like to talk about his screw ups but loves to talk about how he fixed something.
 

451Mopar

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The Hydra mat is expensive, but a good external pump pre-filter is not cheap either. If your modifying a stock tank like Andy, you can add a fuel sump inside the tank that the pump sits into. I think the Fuel pump module Andy is using includes a built in sump?
 

67Charger

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The Hydra mat is expensive, but a good external pump pre-filter is not cheap either. If your modifying a stock tank like Andy, you can add a fuel sump inside the tank that the pump sits into. I think the Fuel pump module Andy is using includes a built in sump?
Yes, a rubber bucket full of baffling foam. BE CAREFUL! I installed mine and unknowingly crushed it down a little during installation and it ended up closing/crushing off the little holes at the bottom that let fuel in. Anything under 1/2 tank, which is the height of the bucket, and my car starved for fuel over 3000. Learned that the hard way during the 1st race after installing the system in a new tank. Other than that, its a great system.
 

Triple Black 73

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The Hydra mat is expensive, but a good external pump pre-filter is not cheap either. If your modifying a stock tank like Andy, you can add a fuel sump inside the tank that the pump sits into. I think the Fuel pump module Andy is using includes a built in sump?

It might be expensive (150 doll hairs!) but it's so cool! The mat works like a big diaper that soaks up fuel then uses capillary action to flow fuel. Awesome design!

Yes, a rubber bucket full of baffling foam. BE CAREFUL! I installed mine and unknowingly crushed it down a little during installation and it ended up closing/crushing off the little holes at the bottom that let fuel in. Anything under 1/2 tank, which is the height of the bucket, and my car starved for fuel over 3000. Learned that the hard way during the 1st race after installing the system in a new tank. Other than that, its a great system.

Are you talking about the Aeromotive kit with the yellow foam bucket looking thing? I don't dig that design, but the mount and pump included in their kits are top notch.

https://www.summitracing.com/parts/aei-18688/overview/
 

Triple Black 73

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Since you're talked about starving for fuel, I got something to admit.

I got started down the path towards EFI because the car was running really lean above 3500 (and cranky cranky cranky when it sat for a while). The car would run great at idle and below 3k but the faster it went the more it chug chug chug. I couldn't get rid of it with timing. The other night I remembered the ONLY thing I didn't remove, replace, refinish, or restore was the original 5/16 fuel line. Back in May of 2016, we had to blow air through it to get fuel flowing. New lines was once on my list to replace but I totally forgot about it so it got dropped. There's strong reasons to think the carb was getting fuel starved due to rust causing blockage in the line. Live and learn, right? Oh well. This EFI system should be pretty dang cool when it's all done.

The progression and knowledge building over the last week has been fairly massive. Thank you everyone that chimed in. I went from trying to modify or replace the original sending unit to having the stainless steal tank professional cut open to TIG welded self for an intake fuel pump with a diaper for a pickup.
 
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