My ’76 F-150 4X2 LWB truck originally had two fuel tanks. The PO had deleted the tank switcher blocking off the line that goes to the aft of rear axle tank and then connected the midships tank directly to the line that goes to the fuel pump. In other words, he was using the midships tank exclusively. After I got it, I installed long tube headers which required removing the midships tank.
The plan is to replace the aft fuel tank and use that exclusively. The problem is figuring out how best to route fuel from the aft tank to the fuel pump under these circumstances.



While most of the fuel lines run inboard of the frame, the tank switcher and the lines that led in-to and out-of it were all outboard of the frame.



Thus, the easy way out would be to follow the PO’s example and run a length of rubber fuel hose from the output of the aft fuel tank line to the input of the fuel pump line. Doesn’t that sound like an unnecessarily vulnerable fuel line?



Alternatively, it might be wiser to keep all of the fuel lines inboard of the frame.



I even have this nifty fuel filter with replaceable element that could become part of the fuel route and facilitate connecting the two lines. So, how would you approach this?

 

Those outer fuel lines look OE, but I prefer the fuel lines to be inside of the frame.

I like that fuel filter, and yes, it could bridge the gap between the existing outer lines, but I think it will bug you and won't look professional !

I had a 3/8'' line customised by a shop to fit last year, and it was inexpensive. (Per below pic)

That said, I'm about to replace the entire line with zinc copper 5/16'' line.

(5/16'' is rated up to 400HP, and my engine produces less than 400HP)

I can do this at home, and I bought a cheap flaring tool for the ends which will attach to short rubber sections.

Basically you'll be doing a custom job, so you might as well do it so that it looks OE.

 

Thanks FMJ for the encouragement to go the extra mile and keep it all inside the frame rails.
On the filter, I was thinking about using that inside the frame rails also but have read that it's not a good idea to have a possibly restrictive filter on the tank side of the fuel pump. The reasoning given was that a mechanical fuel pump does better at pushing rather than pulling fuel.

 

Inside the frame rail is a great idea with a couple of compression couplers to do the job. Although I agree with the push vs pull of the fuel pump, I have a fuel filter on the suction side at the area where you described. It is one of those paper units, but is about 2.5 inches around to make sure that there is always flow. I also use an Edelbrock low psi fuel pump for my Holley. Don't know if that makes a difference, but fuel flow has not been an issue since all these were installed. Hope this helps.

 

Haha ! I think this thread is actually encouraging me to be honest !

The last of my goodies arrived from Summit yesterday, and I spent a couple of hours today planning the new line and pump fitment.

Fitting to the outside is definitely easier than the inside, BUT, inside the frame gives privacy, and prevents crap hitting the parts flung up by the front tyre.

I'm routing my line down the passenger side (right side), up the firewall, and to the carb from the firewall side, so it's a complete custom job.

I've never liked the fuel line coming up over the front of the engine. Maybe I'm just being a girl ! LOL

Hmm, that reasoning seems odd !?

Mechanical fuel pumps pull, and electrical pumps push, and both will be setup for the vehicles given HP, allowing for volume and pressure, and measured in GPH.

I've had my fuel filter on the tank side for the last +/-50,000 miles.
(I didn't like the filter smack bang on top of the engine, and I'd rather keep crap out of the mechanical pump.)

My filter is 100 microns only, but I use a couple of tanks a month and the tank is clean.

I look forward to seeing other responses to the reasoning.

 

I just looked at your ''Rebuilding a wrecked F-150'', which I remember reading back in 2014.

Wow ! What a project !

Fitting your line within the frame will be a walk in the park for you !

If fitting the filter on the tank side worries you, maybe get an opinion from the supplier of the filter.

Thinking about it some more, I can't see any problem in fitting it on the tank side to be honest.