Aux fuel line leak

[clinem03]

Prob a silly question as I think I know the answer, but wanted to try and learn more about how the dual fuel tanks work and the folks in this forum are always so knowledgeable and helpful. I’ve been getting in some dial in miles since restoring my 76 bronco wagon. Got her back on the road today after replacing a rebuilt PS box (AGR rebuilt it) and filled the rear tank (which I’ve done before and used it with zero issues) and the aux tank for the first time, it’s been bone dry since I bought her 2 years back. When I got back to the house I noticed that the short section of rubber gas line connected to the tank selector to the fuel line was leaking like crazy. My initial thought is that it is just the short section of rubber line that needs to be replaced. I never used the aux tank (only used the main tank during the ride) and only filled it with 2 gallons to “test” its seal. Could it be anything other than just that little rubber fuel line where it was leaking (top and bottom at both connections)?

 

[Broncobowsher]

Looks like stock 45 year old hoses. I wouldn't even question it and just replace them.

Now for a lesson on fuel hose. The basic stuff from the parts store, well it is basic. It will be hard and brittle in a couple years. often disintegrating internally as it does so. There is good fuel hose, better compatibility with today's fuels. Barrier hose. Not typically found at auto parts stores. They sell basic hose based on price point, not quality. I use marine rated fuel hose.

And there are clamps as well. I see the original spring clamps on the hoses. They are a better clamp than the worm clamp from the parts store. The bad part, they probably won't be sized correctly for the replacement hose. There are better clamps for fuel lines besides the basic worm drive. I can't think of the correct name for them, but they have an even pressure on the hose a full 360°.

The selector valve itself can also leak. But that is typically inside, around the shaft where the handle is at. Rebuild with fresh O-rings typically takes care of this.
But I would start with the hoses.

 

[clinem03]

Looks like stock 45 year old hoses. I wouldn't even question it and just replace them.

Now for a lesson on fuel hose. The basic stuff from the parts store, well it is basic. It will be hard and brittle in a couple years. often disintegrating internally as it does so. There is good fuel hose, better compatibility with today's fuels. Barrier hose. Not typically found at auto parts stores. They sell basic hose based on price point, not quality. I use marine rated fuel hose.

And there are clamps as well. I see the original spring clamps on the hoses. They are a better clamp than the worm clamp from the parts store. The bad part, they probably won't be sized correctly for the replacement hose. There are better clamps for fuel lines besides the basic worm drive. I can't think of the correct name for them, but they have an even pressure on the hose a full 360°.

The selector valve itself can also leak. But that is typically inside, around the shaft where the handle is at. Rebuild with fresh O-rings typically takes care of this.
But I would start with the hoses.

Awesome, thanks! QQ - what’s the brand of the fuel line you like to use? I did a search for Barrier and didn’t find anything…

 

[Oleguy 74]

i use fuel line rated for fuel injection.just a better hose.

 

[Broncobowsher]

I used https://www.amazon.com/Sierra-116-368-0383-Permeation-Fuel-Feed/dp/B0002CAD9Y/ref=sr_1_10?dchild=1
There are other options as well.

FYI, EFI has a high pressure rating, but often does not have the barrier liner. Earl's Vapor Guard is the only EFI barrier hose I found. I am sure there are others, but they are hard to find.

 

[TheLimeRanger]

FYI from the factory the aux tank hose runs from the selector to a section of hard line and then another small hose from the hard line to the sending unit. The hard line basically sits on top of the tank.