Adding Fuel Return Line?

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Nov 16, 2004
Oceanside, CA (Fire Mountain)
I need to add a fuel return line to the original tank on the 45 for the 3FE. Has anyone done this? I know the tank are different for different years so I wondered where best to put it.

Option 1: Add a return line into the sending unit. This would be the least invasive and keep the tank original. It would also be easy to add on without the dangers (extra steps of purging, dry ice, etc) of drilling and welding the tank.

Option 2: Add the return next to the pickup on the side of the tank like this:


Any suggestions appreciated.

No worries Dom. I'm glad to be of assistance. BTW that is a new from Toyota 72' tank I modified to use in my 78' 45 with a 12HT.
Easy....put it in the top of the tank. My guys used a punch to puncture the tank(no drilling so no particles in the tank.....we did this AFTER we had the tank cleaned and sealed....the port I was going to use turned out to not have the clearance we needed), then we tapped it out and ran in a 45 degree brass fitting(JB Weld on the threads) with the proper size barb on the end. Easy.

Normally I like to drill the return into the flange for the fuel level sensor but we couldn't do it with this setup.

20171129_173633 copy.jpg
I installed a "T" into the vent tube by the fill neck.
I'm not sure my LV had a vent tube in the fuel filler...I would have thought we would have used it if it did. Seems the vents in the LV tank were on the top and hard to tap into due to space. Something like that.

We use the vent tubes in the 40s and the 45LPBs....great spot and easy to hook up.
Closing the loop on this thread. I just used a custom stainless T fitting back into the vent line.

Works well so far... (Sorry I guess I didn't take a pic of the final product before installing)

Mock up...


Installed before clamps...

Thanks for the ideas guys. I read about the T in the vent line but was afraid of dumping fuel back in the area that’s supposed to vent and is near the fuel cap.

Haven't followed thread that close. Are you still using a vented gas cap with a 3FE? With a return line your trying to pressurize the tank and venting a bunch of fumes. While filling the tank wouldn't recommend do it with the engine running. But wouldn't recommend filling the tank any time the engine is running.

Using the original vented cap and not filling up while running. It’s pretty impressive to listen to the return line with the truck running at idle and the cap off. Lots of fuel coming back to the tank.

The seats and tank will eventually come out again once I finalize the tranny hump alterations. If I have any issues with this setup I may just braise a return line into the tank.

Just as an FYI I looked at putting a return line in the sending unit but it’s not an option on the early sender.

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