Fuel Line Question

[Spilfner]

So I need some input on my restoration. I'm working on my 1983 K10, and need some help with what to do with fuel lines. Originally, it had a 3 port sending unit (3/8" fuel, 1/4" return, 5/16" vent or vapor?), and 3 ports on the fuel pump. I have installed a new fuel tank and sending unit. I bought a new 3 port sending unit, but the new fuel pump only has an inlet and an outlet. I hooked up the sending unit to all 3 original metal lines just like it was before. My plan is to plug the return line (at the far end of the metal line by the pump), but what do I do with the 3rd vent line? Should I leave it open somewhere or just plug it off as well?

 

[Taylorb27]

I would get a 3 connector fuel pump. You can cap that 3rd line that goes to the charcoal canister but you will need a vented fuel cap. That is your "vent" line. Without it you will create a vacuum in the tank and have fuel starvation problems. You can also drill a small hole in the middle of your gas cap. Ive seen that before


Why plug your return line?

 

[Curt]

Same situation here.I used the return port on the fuel tank to plumb in a in bed toolbox/aux tank.Worked great.

 

[Spilfner]

I had just read that a return line wasn't necessarily required, so when I got a pump from summit I just got one without the return. The only reason I bought a 3 port sending unit was so I could hook up to the metal lines in case I ever decided to use them all.

I did buy a vented gas cap, will that be enough? For some reason i thought that only let air in but not out...or the other way around.

 

[Curt]

It’s enough.

 

[75gmck25]

Having a return line should help prevent vapor lock. With no return line the fuel dead-heads when the float needle closes off flow, and it picks up more engine heat. With a return the fuel keeps flowing and extra fuel returns to the tank, which pulls cooler fuel up to the pump. YMMV

Bruce

 

[Ricko1966]

Put the correct pump back on it.Throw away the vented cap.As a matter of fact your post starts with you are restoring your truck,altering your truck isn't restoring your truck.GM went to 3 port pumps to prevent vapor lock, everyone went to sealed fuel systems and a purge system to prevent your gasoline from evaporating and to stop condensation(water) from contaminating your fuel and rusting out your gas tank.