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Old 07-04-2019, 12:32 PM   #1
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Join Date: Apr 2018
Location: Penngrove, CA
Posts: 331
'75 C20 dual fuel tank issue/questions

I have a '75 C20 with dual 20g tanks. I've always had trouble filling up my tanks. Here in CA the fuel nozzles have these very annoying "Vapor collar" thingys that completely block off the filler neck to prevent fuel vapor from escaping. In doing so, they prohibit the tank vent from operating properly, which leads to fuel puking out of the filler neck and onto the ground. That's a pain in the ass all in itself, but recently I noticed the filler tube hose on my aux tank was leaking profusely as well. That led me to crawl under there and inspect the system. Turns out all the rubber fuel lines are in pretty shoddy shape.

I dropped the aux side tank yesterday and am in the process of cleaning it up, replacing the lines, and deciding whether or not i need to replace the sender.

If anyone can help chime in on this question, please do.

After pulling the tank, I found this setup at the top:

Untitled by awesome_adawson, on Flickr

Untitled by awesome_adawson, on Flickr

What exactly am I looking at here? And is it safe/legit/factory? I'm assuming that there's a fuel output line, and then a breather, but what sort of breather contraption is that? and is it safe? Also, if i plan on swapping the sender, is it wise to recreate this exact setup?

Another question, I had planned to relocate the tank vent to a location outside the filler neck, thereby eliminating the issue caused by the CA fuel pump vapor collars. has anyone done this? Would there be any hazard or problem with removing the vent hose from the filler neck and just terminating it somewhere under the bed? It would still allow the fuel vapors to escape, hopefully resulting in successful fueling. Thoughts?

Please let me know if you have any experience in the fuel systems in these trucks... Thanks!
"Sweet Pea" 1975 Cheyenne 20
”Otis” 1970 C10 SWB -SOLD
”Chebby” 1962 Impala Sport Coupe
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