Pressure in return line

[Guest RWilliKiwi]

My (other) 78 280's return line, between the motor and the hard line, is hard as a rock and has fuel leaking out of one side of it. Is there an area where these typically get clogged up? Is my only option to strip out the whole line and replace it? Where should I start?

 

Thanks

[innerware]

Just replace that rubber hose. The hoses get real brittle over time and need replacing. Make sure you get high pressure fuel hose though.

[Guest RWilliKiwi]

Its a new one, sadly.

 

edit - But should the return even be under pressure??

[johnc]

Any hose or line that has fluid moving through it is under pressure. When designing, replacing, or modifying a fuel return line you have to assume that it might have as much pressure as the feed line.

[Pyro]

The return line should have only a few psi. 1 or 2 at max for a stock application. And, 1 or 2 psi can leak out. Yes, buy new fuel line and replace it. Use rubber line for fuel injection. If it doesn't say fuel injection on the hose don't use it. You will know you are buying the right stuff when you pay 6.00/foot for it. Any local auto parts store will have it. Get 5/16" hose.

[Tony D]

The Return elbow INSIDE the fuel tank is where the EFI return lines clog!

 

Many times you can rooter it out using a piece of brazing rod cut to have a sharp spade tip to act like a drill to poke through the swarf in that elbow.

 

While the return line should NOT have any appreciable pressure in it, it MUST still have full pressure rated softlines and appropriate clamps as John C said.

 

I have seen 100psi in the header, and then the return line burst AT THE TANK spraying fuel all over the muffler...

 

Nice, huh?

 

My bet would be the elbow inside the tank is where the obstruction lies. Easy way to check: pull the line off at the tank and see if you get freeflow. If so, I lay money you can't pump into the tank through the return line connection!

 

Good Luck Rootering!