96 CB400SF fuel tap leak from vent at the bottom!!!

[daveshep29]

My CB400SF was running beautifully for the first few months of this year. I have moved to Cyprus and shipped it out with me. To do so it spent several weeks on a ship a few more in customs, basically it wasn't started for 2 months.
Now when I start her, she starts but not with her usual enthusiasm and more disturbingly fuel runs from a small hole in the bottom of the fuel tap. It is also coming out of the two pipes that I think are attached to the carbs!
Can any one give me a clue to as why this is happening??

[Superjack44]

My CB400SF was running beautifully for the first few months of this year. I have moved to Cyprus and shipped it out with me. To do so it spent several weeks on a ship a few more in customs, basically it wasn't started for 2 months.
Now when I start her, she starts but not with her usual enthusiasm and more disturbingly fuel runs from a small hole in the bottom of the fuel tap. It is also coming out of the two pipes that I think are attached to the carbs!
Can any one give me a clue to as why this is happening??

Not sure what the small hole is in the fuel tap but the two pipes are probably vent pipes the only way fuel could come from these are if the needle valves are sticking and allowing excess fuel into the float chambers, there are four needle valves 1 per carb it only takes 1 to have a dirty seat to cause problems.
The petrol tap operates on a vacumn from no1 cylinder, try this close the petrol tap and start the engine if the engine runs smoother once the level of fuel is reduced in the carbs turn the tap back on again if it again runs rough turn the tap off again if it again starts to run smooth it would appear the problem is the needle valves.
Another way might be to tap the carbs gently (very) with a small spanner to try and vibrate the needle valve shut .

[daveshep29]

Thanks for the tips. I have been fiddling today, the fuel is no longer running from the overflows but as soon as I switch on the fuel tap it leaks from the bottom.

[Superjack44]

Syphon the fuel out of the tank once empty remove and dismantle the petrol tap and give it a good clean , just in case you forget how it goes together take digi pictures when you dismantle it as to where the bits go.

[Patch29]

Suggest a new tap, probably the diaphragm had perished, I bought new tap from China, hasn't missed a best...

[daveshep29]

Thanks for your replies, I stripped the fuel tap, seemed fine, refitted it and no change so have ordered a new one just in case. Will take a while to arrive from China, will let you know if it sorts it!

[CeeBee400]

I'm looking forward to hearing how easy the new value is to install and if it solves the problem. I have the same issue