[steveo]

simple question;

on a 4-line fuel sender/pump thing, i know which lines are pump and return

but there's a big vent line, and a small vent line

what do they do? one goes to a check valve inside the sender, right?

if i was to put a vent filter on one of the lines right at the tank and block the other one off, which should i use? or does it matter

suprised there's no diagram on shbox

 

[steveo]

decided im just going to tee them both into a filter, but.. still curious

 

[GaryDoug]

One goes to the EVAP canister and the other goes to the bidirectional tank vent valve. Not sure which size goes where. These may help a little:
FUEL TANK & MOUNTING. Fits: 1997 Chevrolet Camaro | Nalley Buick GMC Brunswick
FUEL SUPPLY SYSTEM. Fits: 1997 Chevrolet Camaro | Nalley Buick GMC Brunswick

 

[sweetbmxrider]

Yup, one is that funny looking thing that mounts next to the rear brake line and the other goes to the charcoal canister which is tucked in the driver quarter panel area. You would want a filter on that one if you do away with the evap system.

 

[steveo]

what i did is i put them both into an inline filter, and put a metal fitting with a pinhole vent in it at the end, laying right on top of the tank..

that way not too much evaporation will happen, and if gas does spew out of there for some reason, it'll be restricted in a big way.

i think my fuel pump is a big fan of this setup, as it seems less noisy with consistently atmospheric pressure in the tank.

 

[95 Firehawk]

Sounds like it will work. Just remember the vent also needs to draw in air to displace the dropping fuel level. The pin hole must allow the same volume of air through it as fuel being consumed by the engine so as to not create a vacuum in the tank and a possible drop in fuel pressure at high rpm WOT situations. Just something to monitor for a few tanks of gas.


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