Hi, In a nutshell once I had the charcoal cannister but post suby conversion I have nothing in place. Possibly unrelated but in the summer I pulled into a service station to fill up and my filler cap popped off due to pressure so something is not as I want it's to be. I've run like this for few years but time to fix it but I don't know what's needed or missing. The orig VW vapour pipes still run around the top of the engine joined by the T but then go nowhere (I had blocked them :-/ So what's the best route, I thought maybe getting the suby setup reinstated would make the most sense, mine a early 94 engine. Any thoughts/help or pictures would be grateful. Pg
Most people just run the breather hose straight to the air cleaner, or like me you could get a second hand charcoal canister from a car & put the breather through that then to the air cleaner. You can see it mounted here next to the leisure battery.
The charcoal canister is for emission control so it shouldn’t make a difference if it’s no there, sounds like your fuel tank isn’t adequately vented, perhaps in the summer the heat of the day plus engine heat and empty tank caused lots of vapour and pressure, how’s your tank vented as the cap should have a vent as well as the tank
Hi, I'd blocked off the pipes across the top in my Subaru conversion ( didn't realise) so can unblock and can run into a new cannister. I've bought another cannister, so is the solution to run outlet into the air filter (you said cleaner but it's that the same?) Thanks for the replies, appreciate the help I'm a little bit unsure on this one. Pg
No, you could potentially run petrol straight into the engine like that, have you still the canisters in the rear vents
Hi, No I only had 1 cannister attached to the firewall which I pulled when I did the engine swap so now I have nothing except the pipe running around the top
You are not describing this well. There was never a fuel tank vent canister on the firewall, they are up in the air intakes.
If the original fuel tank breathers are intact from the tank (12) up to the air intakes (10 & 10A) and back down to the T (15A) - where it sounds as if you have joined the ends together - all you need to do is connect the T to the Scooby air-filter/cleaner box. Forget the charcoal canister.
I thought this as that’s all the Vw air cooled engine did but assumed that as it had not been mentioned that it would cause a problem with a more modern engine air intake.
A Scooby engine sucks air through an air filter just the same as a VW air-cooled or any other IC engine.
Thanks everyone (thanks @zedders ). I think I was getting very confused, I'd just blocked off 15A and thought I had to run the pipe (T at 15A) into a charcoal cannister which on my orig FI engine was mounted on the firewall. But I'm reading these are 2 separate things. So I just feed 15A in the diagram into the air filter which should be easy enough. Thanks again for your help and happy New year as well !
Thanks @davidoft , Yes Im good there and I'm glad I asked as I was confusing things. I still have to run the engine fuel vapour as that's last job but I'll do this air filter pipe first. I read the suby had a charcoal canister for vapour so I just need to figure where our how it went together. Thanks again though
Think of the charcoal canister at a filter , it filters out some of the crap to reduce emissions and should be changed periodically
Hi Last Q, I've got another thread which just deals with the cannister (properly now) but on these breathers, I've got an aftermarket air filter so I need to modify it slightly. Should the vent pipe that runs around the top go in at the mouth/inlet of the filter or should it be after the filter? I'm assuming the mouth but a few pictures on the web seem to show several inlets after the filter so I'm a bit unsure. Thanks Pg
Normally after the filter but you said on your other thread that the Scooby has a fuel vapour connection that goes into the manifold and an ECU controls when it opens. Where does the 'engine fuel vapour' come from?
That would be the MOT valve for the fuel tank vapor which is ecu controlled on modern cars. All to do with euro emissions. I would just vent it into the airfilter on the throttle valve side of the air filter.
This explains the ECU control of the fuel tank vapor purging. When pressure in the fuel tank reaches 30-50 mbar (0.435 - 0.725 psi.) the breather valve opens allowing fuel vapors to flow from the fuel tank to the charcoal canister where they are absorbed. With the engine running at a coolant temperature above 70°C (158°F) and the idle speed contact on the throttle valve open the switchover valve applies vacuum from the intake manifold to the purge valve. Thus, the purge valve opens allowing fuel vapor from the charcoal canister to be drawn into the intake manifold via a port in the throttle plate. At a coolant temperature of greater than 95°C (203°F) or intake temperatures of greater than 55°C (130 °F), and a vehicle speed of less than 3 miles mph purging takes places even with the idle contact closed. When a vacuum of 1-16 mbar (.062 - .45 in. Hg) is reached in the fuel tank the breather valve opens drawing air through the diaphragm and fuel vapors from the canister to flow to the fuel tank.
