Does a gas tank that does not have an in-tank pump, need a vent line? Or is a vented gas cap enough? Does it even need venting at all?

I have a dune buggy project that I'm doing with my old LT1 gas tank and it's all ready to go as far as the new fuel bungs, and sump tube, but I didn't build a vent of any kind into it. Emissions do not matter in this case of course.

 

A tank will need some sort of venting, either cap or separate vent. Otherwise as the fuel lowers it creates a vacuum and can stop the flow of fuel.

Jody

 

Thanks alot camojb, so I can either:

A) run a add on tank vent routed to a junk yard fuel evap canister.

How would I do this just runt the vent tube from the add-on tank vent to the canister where it would vent out the other tubes?

B) just run a vented cap and go old style.

Are GM vented caps the same thread as non GM non vented? I could just buy a vented cap once I found a older year that had one.

 

yes,the caps are threaded the same.

 

WooT

Well then, I guess it would be easier to run a vented cap than anything else, so anybody know a f-body that used a vented cap?

 

Well, all the vented caps I see are "cosmetically challenged" to say the least. I can't find one single vented cap that looks like a late model. Surely to god there has to be a late model with a vented cap.

It's like brother where art thou, but with a cap.

 

I'm not surprised you can't find a late-model cap that's vented. They stopped using them many years ago due to smog issues (fuel vapor released into the atmosphere). All the newer cars will have closed systems; vented tanks with vacuum pulling the vapors and recycling them.

I know my 69 Camaro had a vented tank, but it wasn't long after that they got rid of them. My 71 Camaro used a separate canister and non-vented gas cap.

Jody

 

Indeed, the only caps I can find are from 69-70, and as mentioned above, fugly. I found a add-on tank vent, and now I'm leaning towards adding it to the tank and running a hose from it to a evap canister. I found a canister at my local yard for 10$ but it has 3 ports and I'm not exactly sure where to route the hoses. I'm thinking one is an intake and 2 are output? I checked shoebox's sight but even he didnt have a schematic.

 

Anybody have the evaporative fuel canister routing diagram, for a 4th gen?

 

I'll check when I get home from work because I think I still have the cannister and instructions from when I replaced it in my 93 Z28.

 

I appreciate it Jeff. I'll keep checking back.

 

No dice. I must have thrown out the instructions with the diagram. I found installation instructions for 15 different things in my garage last night, but not the cannister hook ups. But check this link for some details on the purge setup LT1 EVAP Purge

 

Thanks Jeff. I can probably cobble something together with the link.


OMG, I just said "cobble"