Gas cap/charcoal canister

[Norwester]

Ok....I just purchased an '86 C10 with dual tanks. I wanted locking gas caps so I went to NAPA and they sold me two non-venting caps. Now I'm wondering if I should have got the venting type??

Another associated question.....I'd like to remove the charcoal canister. Right now, it has one hose coming from it.....the hose closest to the fender. I'm thinking it goes to the fuel tank. This is not the factory engine. Somebody put a crate 350 into it somewhere along the line.

It's not clear to me what I need to do to properly handle the gas tank pressure/venting issue.

Not concerned with needing an emission test as it's not a requirement for this age of truck.

Thanks in advance for any help!

 

[MadOgre]

Ok....I just purchased an '86 C10 with dual tanks. I wanted locking gas caps so I went to NAPA and they sold me two non-venting caps. Now I'm wondering if I should have got the venting type??

Another associated question.....I'd like to remove the charcoal canister. Right now, it has one hose coming from it.....the hose closest to the fender. I'm thinking it goes to the fuel tank. This is not the factory engine. Somebody put a crate 350 into it somewhere along the line.

It's not clear to me what I need to do to properly handle the gas tank pressure/venting issue.

Not concerned with needing an emission test as it's not a requirement for this age of truck.

Thanks in advance for any help!

The tanks MUST be vented. You should have 3 ports on the top of tank on the fuel sending unit. One is a supply line. The others are a return and vent. As long as one of those lines are open to atmospheric vent then it doesn't matter if your caps are vented or not.

the charcoal canister should be routed to the top large 3/8" port on the front of the Quadjet. It is slightly angled towards the drivers side. It is front and top of carburetor. If you have any other carb other than a q-jet it likely will not have the provision to run your charcoal canister. In which case just make sure the tanks are vented some how.

Basically the 3rd vent line from the tank runs to the charcoal canister and is routed from there to the carburetor fuel bowl and is re consumed as fuel.

I have 2 trucks that do not use this system any more and run just fine. Both of mine just vent the tanks to atmosphere and the canister is just totally disconnected.

The canister was designed to trap fuel vapor from entering the atmosphere and re routing it to be used again as fuel.

 

[Norwester]

Ok...are you suggesting that I can snip the line going to the canister and tuck it away someplace so that it still vents? Will that bring air into the tanks and also serve to release pressure in the tanks?

And I thank you for your response.

 

[MadOgre]

Ok...are you suggesting that I can snip the line going to the canister and tuck it away someplace so that it still vents? Will that bring air into the tanks and also serve to release pressure in the tanks?

And I thank you for your response.

Yep you know what the little plastic breather end looks like on the breather tube for your axle?

Just use something like that. My k20 has 4" of tube and then those breather ends on the end right off the tanks. Works fine. Thing is you don't want the line to allow debris or moisture into your tanks and you don't want the breather line to get plugged either.

So long as the tank can breathe you do not need the canister or vented caps.

 

[MadOgre]

I converted a diesel to gas and it did not have vent lines from the fuel senders. So one day I went and bought new caps but they only vented after 2 psi (found this out after my disaster lol) Well one hot day the 1 1/2 psi formed in my tanks pushed fuel out of every where and nearly emptied a full tank of fuel onto the ground LOL IT was a huge mess!

 

[Norwester]

Hey, Mad...I appreciate the help. Not being much of a mechanic, I'm not aware of the part you mentioned. If I went into a NAPA store, what would I ask for?

 

[MadOgre]

A breather tube filter end for what ever size hose you are needing it for. LOL I dunno what the actual name of it is haha

You must be registered for see images attach

 

[MadOgre]

http://www.andysautosport.com/products/goodmark__GMK4044860654.html

 

[Norwester]

You've been more than helpful......my course of action is clear !!

 

[Norwester]

Hey, Mad...I appreciate the help. Not being much of a mechanic, I'm not aware of the part you mentioned. If I went into a NAPA store, what would I ask for?

 

[MadOgre]

You've been more than helpful......my course of action is clear !!

Hey no prob

 

[Norwester]

Well, looks like I led both of us astray. The vent line is not hooked to the canister. God only knows what happened to that line.

The only line that is connected to the canister is the innermost line, closest to the passenger side. It's a hose that goes down under the radiator and attaches to a hard line. Couldn't really see where it goes.

Do I need that line?

 

[Georgeb]

I believe that line that goes down under the rad and is conneced to the hard line is the vent line for the tank.

 

[MadOgre]

Yep that hard line will run back to the fuel tanks. It is your fuel tank vent line.

 

[Norwester]

Thank you Gentlemen!