Hi , I wonder if any of you ever see this , and what this for ? It was found on a 72 Pontiac Formula behind the backseat (the wall that separate from the trunk area) Thank you same part , different angle
it is part of the gastank vent that also is conected the chacoal canister under the hood.my '72 gs has one also
This is the liquid/vapor cannister that is the "brain" of the Evaporative Emissions Control System (EECS). This system was introduced in 1970 in GM California cars and went across the board (except wagons) in 1971. They eliminated the vent in the carburetor, the vents off the tank and also went to non-vented fuel caps. There are 3 tubes on the front of the fuel tank that have a dual function to route gasoline vapors up into this liquid/vapor cannister, but also replenish air into the tank to replace the liquid fuel as it is used up. The air comes back through the 4th pipe which runs to the front of the vehicle to the charcoal cannister. It's the coffee can looking black plastic thing usually mounted down low in the engine compartment and has two vacuum lines on it. One to the intake and the other to the metal line that runs back to the cannister. :bglasses:
This is the liquid/vapor standpipe that is the "brain" of the EECS (Ecaoprative Emissions Control System. This system was introduced in 1970 in GM California cars and went across the board (except wagons) in 1971. They eliminated the vent in the carburetor, the atmospheric vents off the tank, and also vented fuel caps. The standpipe was located up behind the rear seat to get it as high as possible in the vehicle and also protect it from damage. It was eliminated a few years later by redesigning the fuel tank to put a dome on top with resuntant design changes to the rear trunk floor to clear it. Wagons have essentially a vertical tank and the line from the charcoal cannister connects directly to the tank "vent". There are 3 "vent" tubes on the front of the fuel tank that have a dual function to route gasoline vapors up into this liquid/vapor standpipe where it condenses and runs back into the tank as a liquid, but also replenish air into the tank to replace the liquid fuel as it is used up. The air comes back into the system through the 4th pipe which runs to the front of the vehicle to the charcoal cannister. That's the black plastic coffee can looking thing usually mounted down low in the engine compartment and has two vacuum lines on it. One to the intake and the other to the metal line that runs back to the this standpipe. BTW, on the 1971 and 1972 cars, these vent hoses did noy utilize clamps and were the "chinese finger torture" design with cross braids reinforcement that expand in diameter (while pushing on during assembly, but then shrink down when they relax or try to pull them off. These hoses were not under pressure, so no need for the clamps if the right parts were used (not always true). More than once we found standard hose being used that did not have this self tightening fixture. It was a lot cheaper and sometimes the salvage operations made the short connections from longer pieces of non crossbraided hoses. These leaked vapors like sieves. Clamps don't hurt, but aren't correct if you're going for the show points. :bglasses:
sorry i do not have a picture but yes it is mounted beind the back seat.mine looks exactly the same.dave is very good at answering all gm questions.thanx
