BIG underfloor tanks on a '71-what're they for?

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brider

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Some of you may have glanced at my parallel thread on gas fumes in my '71 Pig. Now I've begun researching the fuel system as it SHOULD look, if I hadn't ripped it all out without thinking.

One member posted a diagram from what looks like the SOR cataogue, but it DOESN'T show the big underfloor tanks that were on my '71. I did a search of the SOR catalogue, and could not find these tanks.

Any '71 or early Pig owners out there that can confirm the existence of these tanks, and maybe describe how they're plumbed?
 
are you thinking of the vapor storage tanks? if so, none of my pigs have had them. well, wait..not sure about my 76, i'd have to check that one. but i'm pretty sure none of the others have had em.
 
the 72 model year looks much like the 71 and earlier but without the underbody tanks. Maybe mimic the 72 system if you still have the ones in the quarter panels???

My 7s definitely has the quarter panel tanks, but being a 12/'71 it doesnt have the underbody ones.
 
The diagram of the emissions gear previously posted is of the 72 onwards 55s. The early pig's gas tank vents into the 2 plastic rear thermal expansion tanks and they in turn vent into both the single metal "fuel vapor storage case" and the air cleaner. The FV storage case vents(gets sucked) into the VSV when it is energized which in turn transfers these un-burnt fumes into the intake manifold. There is no charcoal canister involved in the early system. The VSV has four small hoses that connect to the base of the carb, one to the distributor diaphragm unit, one to the throttle positioner diaphragm unit and the last to the ? I have all this gear still in place but the VSV is not set -up - in turn I am suffering from the same problem as you....excessive fumes from the driver's side rear quarter area. I have yet to check all my connections and the state of my gas tank, so i still have some exploring to do.. If you want any specific photos of the the emissions gear, let me know. It is an unfortunate problem to deal with.
 
The diagram Trollhole posted pretty much sums it up, the 09-'71 and on models did not use these underbody tanks, and DID vent into a charcoal canister. Funny, I could've SWORN I removed a charcoal canister from mine along with everything else.

Why isn't the charcoal canister vented into the air cleaner intake?
 
Fuel vapors pass from the charcoal canister to the intake manifold(rather than the air cleaner intake) so that they get "burned":D
 
brider said:
The diagram Trollhole posted pretty much sums it up, the 09-'71 and on models did not use these underbody tanks, and DID vent into a charcoal canister. Funny, I could've SWORN I removed a charcoal canister from mine along with everything else.

Why isn't the charcoal canister vented into the air cleaner intake?
Click to expand...

offkilter said:
Fuel vapors pass from the charcoal canister to the intake manifold(rather than the air cleaner intake) so that they get "burned":D
Click to expand...

Is it possible the canister vented into the frame. My FJ73 had a set up like that on the line from the tank .
 
Gas fumes

Sherman is an early 72 FJ55. We always smelled gas, especially when the tank was half full or more. If I remember, it turned out it was a crack in the vent line that runs parallel to the filler tube into the gas tank. I replaced that and all was well.
 
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