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Where do you guys run your gas tank vent lines to?

Arrover

Arrover

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I'm replacing the soft fuel lines around the dual tanks and tank switch on my crew cab. The vent lines that were on it were only 2-3" long without any sort of breather cap on them. I do not have a charcoal filter to run them to. Do you guys just have a short hose with a breather cap on them or do you run the vent hoses somewhere? I was thinking that I could run them up higher between the bed and cab and then cap them with breather caps. They would be more exposed to rain that way though. I could run them into the bed area. I won't be intentionally crossing any really deep water but I wouldn't mind if the truck were more prepared for it just in case.
 
I ran mine from the top front of the tank towards the pass side, then towards the rear, then towards the drivers side all on a downward slope until it was below tank level, then at the end, I pointed the line upwards so it was above the tank level with a filter/check valve on the end.
 
charcoal canister
seems to do fine (though truck isn't idling currently, will update if it's the vents fault lol)
 
I'd agree with retrofitting a charcoal cannister. It's such an insignificant concern in reality installing a charcoal cannister would be a pain, but it's probably the overall best solution.

Outside of that, do what I've done for the last ~12 years. Plug the vent with a bolt, and vent your gas cap. They aren't complex, you can easily make them vented.
 
Thanks guys. The vented gas cap is pretty simple. I think I'm going to look into that.
 
FWIW I have had *no* luck finding vented gas caps, which did exist OEM. No idea why stant and the like are selling non-vented as vented, but they are. In actuality even the non-vented caps are vented, but it's at something like 16PSI.

The caps I've dealt with come apart pretty easily, and it's pretty easy to figure out which "valve" does what.
 
Thanks Dorian. That's good info. I've got two pretty new locking caps so I'll take a look at venting them. Thank you guys for the help.
 
I fought fuel tank venting issues on my K10 since 2008 when I installed the 8.1L. The truck doesn’t have a charcoal canister and there is no room for one under the hood. I found “vented” fuel caps were anything but vented. Even the so called diesel caps that are supposed to be vented even more. For the last few years in hot weather I had to drive the truck around with the fuel caps loose to keep the pressure down. There were a few times on desert off-road trips the tank would build so much pressure the fuel pump would start screaming then stop.

Finally last winter I dropped both tanks for some other maintenance reason and ran the vent hoses from the tank up into the fuel door area held on with a p-clamp with an axle vent plug on the end. That is basically how all the new GM trucks are vented. The only difference is on the late model trucks the vent comes from the charcoal canister to the fuel door area whereas mine is from the tank to the fuel door. I bounced the truck all over AZ and UT this summer and it works great. No more issues with pressure build up in the tank and there also hasn’t been any fuel spill or sweating from the new vent location. So far so good :waytogo:
 
Awesome Larry! Thanks. Now I've got a couple of good ideas that I hadn't thought of.
 
No concern for rollover protection?
 
76zimmer said:
No concern for rollover protection?
Click to expand...


Yeah, a little bit. More of an incentive to keep the shiny side up :haha:. The interesting thing is a few times I’ve forgotten to turn off the fuel transfer pump and overfilled the LH tank (main tank) where fuel breached the fuel cap anyway. Not a drop got pushed out of the vent. Damn vented caps don’t vent worth the s hit but they sure let fuel spray out :dunno:. If this camper truck ever rolls over I've got bigger problems to worry about. Might as well let her burn and sell it to insurance :haha:
 
dyeager535 said:
I had my tank out the other day. Pretty sure the stock sender has a rollover valve on the vent.

Different setup, but I'm 99% sure mine is set up with the rollover valve on the vent line in the same location as this: http://www.gmforum.com/howto/p0440/Rollover_Valve_2.jpg
Click to expand...


Ah, you're right. I remember seeing those valves now on the vents on the sending units in both tanks. Probably explains why when I overfill the LH tank with the transfer pump fuel never gets pushed out the vent. Forgot about the check valve on the sending unit. Now I feel better about my vent location :haha:

Here is the vent on the RH tank. The LH is just like this. My 2001 Silverado is similar.

IMG_20141008_161218_348.jpg
 
If it were me, if you ever need to deal with the vents again, look into modding the cap. The one I have I didn't even have to modify it, I just took one of the rubber "valves" and wedged it open. No drilling, cutting, nothing. Not trying to impose my will, I just don't think many people have actually opened up the cap and looked at how they work.

Obviously for those that the EVAP cannister won't work, as it's just a better option if practical.
 
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