55.2-59 Fuel Tank Vent

[57FleetsideC4]

Hi All, As my 57 pickup project is getting closer to done I have a fuel tank question. My tank is located in the bedrails in the back LS power and has a roll over valve on top with a nipple. I am guessing I need to vent the tank. I ran a hose from that nipple forward along the bed. Actually I am thinking of running it between a heat shield and the bed. Does this sound like a good idea? Thanks Steve

[dsraven]

vent hose should end higher than the tank so, worst case scenario, no siphon effect can happen. I try to end the hose as high as possible
hose should be run with a smooth uphill flow, held with clamps along the route as required
a vent cap, like a differential would have, should be used on the final end to keep dust etc out
I always try to end the hose behind something so road splash doesn't have a chance to plug it. sometimes on the rear of a cross member or back along the tank filler hose so it vents near the filler, which is usually substancially higher than the tank. sometimes I will also run the diff vent hose along with it since it also needs to be placed somewhere with the same thought process
shield the hose from heat where applicable
also install a ground wire from the filler cap to the tank to stop static charge when filling. since the filler is insulated from the tank it's important

[Hcb3200]

"vent hose should end higher than the tank"

Yes and no depends on where your filler is.

If you have the filler at stock location by your door then when you fill and the vent is below that level then you could have a situation where gas will go in the fill then flow out the vent.
So you want he vent exit as close to or above the filler hole.
if you have a bed fill location then putting the vent on a crossmember or near the truck bed is high enough. From the looks of your build thread unless you changed it this is the case.


are you going to put a charcoal canister on it so that you don't have the vented gas smell?

In my scenario for that i ran the vent up and inside the sheet metal above filler on door then back down so the top loop was above the filler. then back under the truck and into the charcoal cannister then vented.

[mr48chev]

Ideally you want the vent hose to vent higher than the top of the filler neck. Plus run a filter of some sort or a charcoal canister. I've seen some folks run the vent hose for the rear mounted tank up the stake pocket with a filter on the end. One gave off a strong wiff off gas when you walked close to it on a hot day at a car show though. I found that when I was taking photos of the bed wood and pinstriping on the back of the cab.

[57FleetsideC4]

Thanks for all the great information. My tank fill is in the bed just above the tank. I think I will get an inline fuel filter to put on the end and it is almost level with the fuel fill cap. Once I start ti drive it will see how it works out. Thanks again Steve

[Stepside Jim]

I just finished building my tank and used a check valve / screen / cap from tanks inc.

I mounted mine inside the driver side rear wheel well as high a possible.

I also installed a fuel filter along the way to slow any possible fuel flow and air flow.

There are two holding clamps coming off the rear fender mounting bolts hold all in place.

The top piece is enclosed except for a small opening on the backside where there is a screen to breath and keep crud out.

It's been kept in a well closed building and in 4 months I've only gotten a smell of vented gas one time.

The pic of the vent line in the wheel well is sideways.

[mr48chev]

Originally Posted by 57FleetsideC4

Thanks for all the great information. My tank fill is in the bed just above the tank. I think I will get an inline fuel filter to put on the end and it is almost level with the fuel fill cap. Once I start ti drive it will see how it works out. Thanks again Steve

On that one you want the vent several inches higher than the filler.
The issue is that if you fill the tank and park the truck out in the sun the gas will heat up and expand and if the vent isn't high enough the expansion will push gas out the vent or in my case the vented cap. I made that mistake whne going to an event where I wanted to be on the highway for a long trip home right after the event and had gas leaking out the vented cap while sitting at the event. My bad that time for not leaving any room for expansion.

[dsraven]

as a firefighter I have been to many calls where someone topped up their tank on a full day. the gas from the underground filling station tank is quite cold and then the vehicle fuel tank is topped up. the gas warms up, expands, and no matter what vehicle you have there is going to be problems. leave lots of height above the filler if you can. your truck, do what pleases you and you think is right.

[57FleetsideC4]

Thanks for the information guys. This is a work in progress so will see what I can do to get it higher up. Steve