MG Car Repair: Evaporative Loss - Liquid Loss, charcoal canister, vent hose

Question
I have a 72 MGB with the original Su Carbs still in place, recently I went to take her for a spin and noticed a fuel smell. I found that the Evaporative Loss Canister was puking fuel out what appears to be the drain hose. It wasn't just a minor drip but a stream similar to what would come from the fuel lines if diconnected fter the fuel pump. I don't believe any vacuum lines have been rearanged in the 3 years I have owned the car since I haven't touched them. Obviously I would need to replace the Charcoal canister, but would like to know the cause of the fuel loss first. Any thoughts?

Answer
Hi Jason,
Fuel in the canister can only come from two places, the vent for the fuel tank and the vent from the carburetor float chambers. About the only way it could come from the tank is for the tank to be overfilled.

The most likely is that one or both carbs flooded and it migrated to the canister. You can test both carbs now by removing the vent hose from the float chambers and rout it down to a catch jar or can. Then turn the key on and let it set for a while to see if the carbs are flooding now. If not it was still likely that a piece of trash was in a float needle and caused the flooding of one or both carbs. Make it a habit never to leave the key on without the engine running because there is constant fuel pressure on the float needles when the key is on. Even good needles can seep a little with fuel pressure on them. Also you may want to test the fuel pressure especially if you have replaced the fuel pump as some pumps pump too high pressure for the car. 1 to 3 PSI should be MAX. I found some aftermarket pumps the were 5 to 7 PSI.
Howard