Do I even need a gas tank vent tube?

[projo198]

On my '78 K10 when I replaced a leaking gas tank I moved the mounts up so that the tank didn't hang so low below the body. In doing so I believe I caused a fueling issue because now it takes forever to fill without the fill tube locking up and spitting gas out.

I've been researching remedies, but wouldn't a simple one be plugging the existing vent tube from the fill assembly and running a hose and filter directly from the tank vent port upwards and mounted to the truck? Much like we do with our differentials and transfer cases to keep water and dirt out.

Only sacrifice I see is this won't automatically shut off the pump handle at the gas station.

Thoughts?

 

[Bloodhound1981]

That is the setup I have on mine, but that's because I relocated the tank to the rear with a blazer tank, and my fuel filler is now in my bed. I have a vent hose going from the tank into the top inside of the wheel well, with a filter on it. As long as the height of the vent is higher than the fuel filler hose, the pump handle shuts off when the the filler hose fills up to the nozzle. One of the potential down sides is people say you can get a fume smell when parked. But mine lives in the garage, and I have zero gas fume issues.

 

[Bextreme04]

On my '78 K10 when I replaced a leaking gas tank I moved the mounts up so that the tank didn't hang so low below the body. In doing so I believe I caused a fueling issue because now it takes forever to fill without the fill tube locking up and spitting gas out.

I've been researching remedies, but wouldn't a simple one be plugging the existing vent tube from the fill assembly and running a hose and filter directly from the tank vent port upwards and mounted to the truck? Much like we do with our differentials and transfer cases to keep water and dirt out.

Only sacrifice I see is this won't automatically shut off the pump handle at the gas station.

Thoughts?

Your problem has nothing to do with the vent. The saddle tanks are notorious for having the fill tube almost horizontal, which makes it hard for any volume of fluid to move through the tube and into the tank while filling. When you moved the tank upwards, you made the fill tube go past horizontal and now I bet your fill tube actually goes upward to the tank... which is obviously a problem when you need fluid to be moved along by gravity. You need to move your tanks back down or convert to a single blazer tank.

 

[TotalyHucked]

^This

 

[Zelph]

The above advice would be applicable if you are not on a body lift. Based upon your avatar pic and moving the tanks up I assume that you do have a body lift?
Either way, I would suggest running a vent line to a charcoal canister.

 

[projo198]

Your problem has nothing to do with the vent. The saddle tanks are notorious for having the fill tube almost horizontal, which makes it hard for any volume of fluid to move through the tube and into the tank while filling. When you moved the tank upwards, you made the fill tube go past horizontal and now I bet your fill tube actually goes upward to the tank... which is obviously a problem when you need fluid to be moved along by gravity. You need to move your tanks back down or convert to a single blazer tank.

Thank you. The hose still has a downward angle but likely not enough like you said. I will do some research on the blazer tank, have not heard of that. I only have 1 tank now.

 

[75gmck25]

Blazer and Suburban tanks will fit if you have no spare tire. Not sure the big 40 gallon Suburban tank will work, but smaller tanks definitely fit.

 

[projo198]

Well I feel dumb. The vent hose had in fact kinked behind the fill tube. Instead of paying $25 for the correct hose I just added a brass 90-degree PEX fitting and voila! Took 5 gallons without a drop lost.

You must be registered for see images attach

 

[Zelph]

Gotta love when it’s a simple fix.

 

[Grit dog]

Thanks for posting the solution.
It’s prompting me to look at my 77 now.
The aftermarket saddle tank actually fill a little easier than the factory one. Wonder if the vent tube is collapsed?
Any of the vapor recovery style pump nozzles also absolutely suck for filling old school vehicles in general. That’s part of the problem. Lol

 

[TotalyHucked]

Thanks for posting the solution.
It’s prompting me to look at my 77 now.
The aftermarket saddle tank actually fill a little easier than the factory one. Wonder if the vent tube is collapsed?
Any of the vapor recovery style pump nozzles also absolutely suck for filling old school vehicles in general. That’s part of the problem. Lol

Yep. It's a 50/50 shot if I can leave the cruise control on the slowest setting or if I have to sit there and babysit it while it clicks off every half gallon

 

[CalSgt]

Yep. It's a 50/50 shot if I can leave the cruise control on the slowest setting or if I have to sit there and babysit it while it clicks off every half gallon

Once upon a time when I worked at a Full Service gas station, many of the squares (and a few others) we would flip the hose nozzle upside down and they would pump without interruption.

 

[Zelph]

^thats how I fill my Corvair.

 

[TotalyHucked]

Once upon a time when I worked at a Full Service gas station, many of the squares (and a few others) we would flip the hose nozzle upside down and they would pump without interruption.

I've always read about that online but never think to try it when I'm at the pump