Had some problem a few weeks ago on my 77 SC. Ended up replacing fuel filter and fuel pump on the side of the road with my camper on back. When I get in it, it sounds like it is starving for gas. I have replaced most of the rubber line on it, but being a SC with Dual tanks, am ponder replacing all the hard lines with rubber. There are some really tight and goofy bents in the steal lines an this truck.

Any pros or cons to running all rubber lines? Any particular product I should use?

 

Long rubber lines tend to collapse after a while especially with today's crappy fuel. They also tend to "flake off" internally boogering up the carb...unless you have a fuel filter between the pump and carb.

If you're planning on rubber lines anyway, go with the fuel injected lines. They're expensive - around a buck per foot, I think, and made to withstand today's fuel.

 

Why not make the long runs with hard line and use flexible rubber for the tightest bends? It'll be more work to install, but Filthy Beast is right, the ethenol in modern gas eats rubber (also plastic, aluminium, zinc, and carburetors...cuz they're made out of that stuff). Unless you can fill up regularly with NE 92 (NonEthenol 92), you're best bet to avoid roadside fuel system repairs is to keep the rubber to a minimum...or use the FI line which is made for crappy gas.

Also it's good to remember that flex line will kink when bent too far. The same can be said of hard lines, but if you make a good bend, it'll stay good. Rubber gets weird with use and temperature...it could close-up on you at any time....probably somewhere "inconvenient".

 

I very seldom use ethanol, unless I forget while in a hurry, in my dents. Maybe 1 out of 20 tanks full.

I currently have the existing hard lines in place, but my problem is there are like 8 small chunks of rubber line, some of the hard line has really stupid complicated bends. I am just looking for an alternative to the factory system. Since FI line has a weave in it, is it less likely to collapse?

 

Normally a good 3/8" hard line is your friend... tough and not restrictive.

The short rubber lengths can be a problem. If they are old and soft suction can collapse them causing the problem you are having. I had a similar problem. Replace them if there is any question but suggest you keep the steel.

Another possible problem is a partially blocked pickup screen in the tank.

Yet a 3'rd possibility is vapor lock when the engine is running hard and pulling a lot of fuel. I had this issue after replacing the OE 3/8" pickup with an available 5/16" re-pop. She would fall over with any heavy sustained throttle. The system was right on the edge and couldn't handle the slight additional restriction. Confirmed with a fuel pressure gauge "T'ed" into the line feeding the carb. Heavy throttle in hot weather pulled fuel pressure to near zero. The fix for that was a rear frame rail mounted electric pump... which also helps her start a lot easier/faster.

 

Another issue with rubber line is that it will crack after it gets hard and usually does so at a bend or connection. Yes, the hose with the weave in it will hold up better, but steel line is still the better way to go.