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Returning fuel to the tank

Old 11-27-2020, 12:04 AM
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Default Returning fuel to the tank

Hello and Happy Thanksgiving,

I am returning my fuel back to a 90 gallon tank after the pressure regulator. This is an EFI setup with approx. 55 psi fuel pressure. Does this return fuel need to go thru a pickup tube (dumping fuel at bottom of tank) or is it OK to simply dump it into the tank thru one of the bungs at the top of the tank? I have an extra pickup tube that can be used for this if needed but at the time of rigging I didn’t think it was necessary so I removed it. Now I am second guessing myself as my concern could be possible aeration of the fuel as it dumps in at the top. Probably overthinking this but wanted to get some opinions from more experienced folks.

Thanks
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Old 11-27-2020, 08:11 AM
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Gas can go back high or low, doesn't matter
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Old 11-27-2020, 09:57 AM
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Ideally you want to add the return to the pickup to not cause aeration when running low fuel level. You can get a fuel fill return adapter or return return at the filter head. I believe high pressure From the top of the tank into fuel might be the worse case scenario.
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Old 11-27-2020, 10:28 AM
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On my 28 cig I built a hose splice the had a fitting in it that I returned my fuel into the Fuel tank fill hose. I had no bungs on the tank I’ve never had an issue with my 650hp blown small blocks
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Old 11-27-2020, 10:44 AM
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Not to disagree with the Fuelab vid, but as they said, there using mineral spirits which does foam more then gas. Also note the amount of fuel being returned is quite a lot in 2 of the 3 set ups. If there is a high volume pump (something like aeromotive a1000) then maybe. The pressure going back to the tank is low once it leaves the reg.

I have MPI using a 40 psi pump and the return goes back to the return to tank fitting which is near the top and have had no issues. Even ran out of fuel one time because of fuel gauge issue, and noticed nothing until the motor started dying (was heading to fuel dock on plane)
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Old 11-27-2020, 11:10 AM
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I`ve been dumping the return next to the the intake for years .
With EFI I`m running a 2 stage Holley pump. second stage only comes in after 3# of boost.
No need to run the fuel pump at full power while at idle etc



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Old 11-27-2020, 11:19 AM
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Thanks guys. Appreciate the input.

‘Running an a1000 pump so I am returning a lot of fuel I suspect as this is a moderately built 502 mag.

I am heading to the boat shortly to check how I plumbed it. I just looked for my original pickups and only found 1 which means I may have actually plumbed the return through a pickup tube and have forgotten that fact. I had to make a new supply pickup so I had two left over pickups in total. I think either way I am probably OK, but I have really easy access so I will plumb the return thru the pickup and send the fuel to the bottom of tank if it’s not already done that way.
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Old 11-27-2020, 11:43 AM
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Hope fuel doesn't get to hot with the a1000
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Old 11-27-2020, 11:46 AM
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what efi are you running that requires 55# of pressure
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Old 11-29-2020, 11:57 AM
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Originally Posted by F-2 Speedy View Post
what efi are you running that requires 55# of pressure
It was dyno tuned with the same fuel delivery setup (a1000 with return) and that is where the tuner set it. It is basically the stock 502 fuel rail and injectors with #7 opened up. I also thought that was crazy high pressure as the old fuel setup was around 38 psi. I eliminated cool fuel setup, etc..

What are the drawbacks to too much fuel pressure?
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