Hi all, grateful for any help. My 900ss has been standing for a few months. Previously ran well. Starts ok (now that I’ve changed the start switch and relay) but the Airbox is flooding with fuel. Any ideas ? I’m guessing it’s carb related? Thank you!
I would think more tank related, as this is (obviously) above the carburettors? Have you checked the tank integrity plus fuel gauge, petrol tap, drain plug and two hose connections for weeping? I know I'm stating the obvious, but have a look for weeping at all five possible junctions plus perforation of the tank itself. can't think at the moment how any of these would lead into the air box, but route has to be from above obviously. does your airbox retain the standard top, or is it a cutdown version?
Hi, thanks for replying. Tank and hoses all looks fine tbh. All hoses are ok, no leaks or weeping. Airbox and filter all standard. The fuel is coming in from the black plastic pipe connected to the two black boxes under the seat (ignore my terminology ignorance). I’d read that if carb floats are stuck this could be an issue…I’ll recheck the fuel tap ,wanted to ask before I start removing things. Appreciate your response.
so sounds as though it's being pumped in by the fuel pump? Does sound a bit bizarre as you've not changed anything have you? i'm sure you've also checked for a pinched fuel hose, even wondering if you still have the small thimble filter in the supply line and it's decided to block.
it does sound like you could be right, and one of the needle valves is not shutting off, it's incredible that it's managing to return all the way via the breather though, I guess that's what you mean? The hose that goes to the little plastic boxes mounted to the left and the right of the frame.
Hi Chris, not changed anything other than starter switch assembly, starter relay, then got flooded on start up. I’ll recheck all lines as you say, incase I’ve pinched a hose etc. Was just curious incase was a familiar issue with anyone. That’s my Saturday now planned…
i've never had this happen on a Ducati hopefully someone else has, and will pick this up and confirm.
Not sure what's happening here but generally if the needle valve is not sealed then the fuel can leak past the inlet valves, into the bore(s) and into the sump so would first check the oil sight glass to see if it's overfull and before trying to start it take both plugs out and turn the engine over by hand to make sure there is no fluid in the bores. Can only think the whole contents of the tank have leaked into the crankcases, and escaped via the engine breather into the catch tanks under the seat.
Thanks Chris, really appreciate you responding. I’ll recheck everything and repost (no doubt admitting some incompetence) if I can sort it. Cheers.
thought of this, and nearly added the same, but don't believe the crankcase is capable of venting up into the air box if it hasn't run.
just a thought, did you run the bike? maybe I missed this, as if you did, and sump is full of fuel then a small amount could vent into airbox, and have had this before.
My initial thoughts as well, but hypothetically gravity fed fuel could fill the crankcases, travel up the breather pipe to the breather tank under the seat and then along the breather tube into the airbox. A route normally reserved for dispensing with air/oil vapours vented from the crankcase, but if there is a sufficient head of fuel that may be what's happening here. Most important thing at the moment I would say is not to try and start the engine if one of the cylinders is full of fuel and the associated problems with hydraulic lock. Potential fire risk as well if a lot of fuel has escaped. Certainly be interested in the OP's eventual findings.
