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Gas Tank switch .
Posted: Mon Oct 16, 2023 1:04 am
by Psychagogic
Re: Gas Tank switch .
Posted: Mon Oct 16, 2023 6:40 am
by Stuka
Welcome to the forum.
The fuel lines (sending, return, and vapor lines) all connect to the sending unit itself (EDIT: This is not true of older tanks (per the post below this and the TSM), and there is a vent line on top of the tank even on newer tanks). The tanks from 63-77 are all roughly the same as far as I know (Or at least, the replacements list those years as compatible).
As for if you NEED the vapor canister. Technically no. But they do reduce fuel vapor smells as the carb won't vent to atmosphere under the hood, or external if you use a vented fuel cap (required if you don't run the charcoal canister). Your original canister may or may not function as a vapor canister after 50 years. The purge valve may no longer function, and the charcoal may be depleted. You can buy new replacements if you choose to go that route.
Re: Gas Tank switch .
Posted: Mon Oct 16, 2023 6:59 am
by tgreese
A '72 is different wrt the vent lines. Look at the picture in the TSM, page 4-1-3. Also look at the emissions chapter. A V8 truck will have a charcoal canister. The charcoal canister is under the hood; the tank at the rear is an expansion tank, meant to block liquid fuel getting to the canister.
Your original tank has maybe four lines going to the expansion tank. Each of these comes from a corner of the tank, so that the air bubble above the fuel always communicates with the canister. The replacement tank will have one or maybe two vent lines, with much of the plumbing to each corner internal to the tank. It's ok to connect that one line to the expansion tank, and plug the rest.
TSM.png
As Stuka points out, you don't _need_ the charcoal canister. However, it vents your fuel tank, and you must provide a vent somehow. Lacking the vapor recovery system, typically this is via a vented gas cap. Note aside from the emissions question, your Jeep will smell of gas without the vapor recovery system.
First post! Welcome from Boston.
Re: Gas Tank switch .
Posted: Mon Oct 16, 2023 1:56 pm
by tgreese
Jeep72TruckFuelTank.png
NB this is the Thriftside (aka step side) pictured, and the filler neck parts are different from the more common Townside. There is a picture of the Townside parts in the '62-73 parts book free to read and download on the Tom COllins site. COnfig of the plumbing is the same for both models however.