Unidentified hard line from Fuel Tank

[goathearder]

Hey Guys,
In the midst of troubleshooting another issue, I'm replacing the fuel pump and soft lines. At the tank, there are two soft lines that run to two hard lines on the frame rail. The upper hard line on the frame rail supplies the mechanical pump but the lower hard line doesn't seem to do much.

Where the upper hard line goes to the pump, the lower hard line runs across the front of the motor and terminates near the power steering pump.

I'm guessing that this was supposed to go to some kind of Vapor Control canister which would explain why the damn truck smells like gas all the time.

Can anyone confirm?

If it did go to a vapor control canister, what can I do? Just leave it open? Hook it to an aftermarket canister?

Thanks,
John

 

[sweetk30]

3/8 = fuel feed / suction

5/16 = return line if return line fuel pump is used or efi

1/4 = vapor / vent line to charchole canister on core support. ( ends near p/s pump )

 

[goathearder]

I totally think its a vent line. I didnt even know 73s had vapor canisters. Anything i can connect it to instead of buying a freakin 80 dollar canister or just leave it open?

 

[sweetk30]

if your gas cap is a vented style then cap it off.

if not then i cant safely say were in my past experince

 

[goathearder]

How do i know if its a vented style?

 

[K85 Octane]

How do i know if its a vented style?

suck and blow on it, J

I dunno, vents in the end

 

[goathearder]

suck and blow on it, J

Hahahaha, turns out this is right! It lets air in when you suck on it (all gas caps do apparently) but nothing when you try to blow air out which means its a sealed cap.

Now, none of the autoparts stores around here offer a "VENTED" cap for a 73 K5. Anyone know where I could get one?

 

[dyeager535]

I never had any luck finding one. The parts store manuals all list the incorrect one.

Can you post a picture of the gas cap?

I can tell you from experience that if it has a black rubber "tit" sticking out on the underside, which is obviously part of a valve, push that in with a small screwdriver until it goes under the guide, and push it out of the way so it no longer aligns with the upper guide. That will vent the cap.

 

[goathearder]

My current is a locking gas cap and I can't see anything that looks valve like on it. I actually just bit the bullet and ordered a vapor canister. NO ONE carries one for a 73 blazer for some reason so I ordered one for a 77 blazer which apparently everyone has. I can live with 50 bucks to reduce the smell of gas in my garage.

 

[dyeager535]

I tried to find pics, can't find any unfortunately. I think the vapor canister is the right solution, sucks the right caps are nowhere to be found.

I had an old vented cap and it stopped venting for some reason, so I ended up just wedging that piece (the end of the valve) as I suggested. It really doesn't look anything like a valve, you can just tell when you depress it, but I suspect different brands/types of caps are assembled different. Is it a stant locking cap? I have one on my '87 I can check, as I'm now curious.

 

[goathearder]

Its a MCS Masterpro cap from Oreillys.