rumpfy
19-05-2013, 07:15 PM
The charcoal cannister fitted in the emissions control part of the fuel system uses the property of 'ADSORPTION' to trap fuel vapour. Vaporised fuel flows into the cannister through the 'TANK' port AND the 'CARBY' port. The vapors are trapped in the cannister until the 'Purge Valve' is opened by vacuum taken from ABOVE the throttle flap; and then the airflow through the cannister is induced by a hose connection from the purge valve to the inlet manifold.
The charcoal granules are held inside the cannister by a sheet of foam 'rubber'. There is a sheet of this material at the top of the cannister and this sheet stops granules from being sucked into the engine AND the carby. At the bottom of the cannister there is a spring loaded ventilation disc which has a sheet of the foam material. Over time, the foam breaks down and the cannister leaks granules. At the very bottom of the cannister, there is a plastic disc which is heat welded to teh cannister body.
The bottom disc must be cut away from the cannister body. Cut the plate around the inside surface of the cannister. Remove the plate and the spring loaded disc and tip the granules into a bucket.
Clean the bottom disc of all the foam, and also clean the top of the inside of the cannister.
I used some 'craft felt'. This material is a felt and is porous to fuel vapors.
I glued the felt to the plastic material of the cannister using a contact adhesive.
The top part on the inside of the cannister is a pain and needs to be done with some patience. I used a leather punch to punch holes on the required grid. errors in hole location didnt matter much because the felt can be pulled around to fit the holes over the pins. When you open the cannister it is obvious what is going on.
To reinstate the bottom cover, I made up a couple of steel angle pieces and fitted these to the bottom of the cannister and fixed them with self tappers to the thick edge of the cannister body. The bent up edge is only say 3 mm deep and goes approximately at the side of the large central hole in the bottom cover. Its probably neater to have the angle supports parallel to the bulkhead.
Note that when the granules are inside the cannister and under the force of compression from the spring, then it will be difficult to hear any granules rattling around.
I recommend the cannister be checked AND repaired because I found on my carby that over time, the granules had been sucked into the region behind the 'Bowl Vent Valve'. These granules are hard and they wore holes in the diaphragm of the BVV and effectively destroyed it.
My work has indicated that the BVV is CRITICAL to achieving good fuel economy. I will discuss this aspect in further posts on another thread.
Took me about 4 hours to repair/rebuild the cannister.
The charcoal granules are held inside the cannister by a sheet of foam 'rubber'. There is a sheet of this material at the top of the cannister and this sheet stops granules from being sucked into the engine AND the carby. At the bottom of the cannister there is a spring loaded ventilation disc which has a sheet of the foam material. Over time, the foam breaks down and the cannister leaks granules. At the very bottom of the cannister, there is a plastic disc which is heat welded to teh cannister body.
The bottom disc must be cut away from the cannister body. Cut the plate around the inside surface of the cannister. Remove the plate and the spring loaded disc and tip the granules into a bucket.
Clean the bottom disc of all the foam, and also clean the top of the inside of the cannister.
I used some 'craft felt'. This material is a felt and is porous to fuel vapors.
I glued the felt to the plastic material of the cannister using a contact adhesive.
The top part on the inside of the cannister is a pain and needs to be done with some patience. I used a leather punch to punch holes on the required grid. errors in hole location didnt matter much because the felt can be pulled around to fit the holes over the pins. When you open the cannister it is obvious what is going on.
To reinstate the bottom cover, I made up a couple of steel angle pieces and fitted these to the bottom of the cannister and fixed them with self tappers to the thick edge of the cannister body. The bent up edge is only say 3 mm deep and goes approximately at the side of the large central hole in the bottom cover. Its probably neater to have the angle supports parallel to the bulkhead.
Note that when the granules are inside the cannister and under the force of compression from the spring, then it will be difficult to hear any granules rattling around.
I recommend the cannister be checked AND repaired because I found on my carby that over time, the granules had been sucked into the region behind the 'Bowl Vent Valve'. These granules are hard and they wore holes in the diaphragm of the BVV and effectively destroyed it.
My work has indicated that the BVV is CRITICAL to achieving good fuel economy. I will discuss this aspect in further posts on another thread.
Took me about 4 hours to repair/rebuild the cannister.