Where do the B30 series fuel tanks vent or breathe?

[DevonOrange]

I have a B2530 (EU model but same as other B30 series so lik3 a B2630). Recently I have been struggling with fuel starvation and the engine dying and have narrowed this down to a vacuum in the fuel tank. When operating for a little while and I open the fuel cap, I get a big suction sound and there's definitely a vacuum in there.

I've checked the fuel cap and it doesn't look like it vents or is the breather type. Just the cap and a rubber seal under there.

I was wondering where the tank would breathe from so I can check if that may be clogged?

These are the pics I have for the tank and related connectors:

Thanks!

 

[GreensvilleJay]

gizmo #120 'magically' vents out hose #030 ?
maybe mudwasp has plugged the hose

lightly blast air 'backwards', see what comes out of the hose ??

 

[DevonOrange]

gizmo #120 'magically' vents out hose #030 ?
maybe mudwasp has plugged the hose

lightly blast air 'backwards', see what comes out of the hose ??

Sorry, I posted lots of pictures with 30s and 120s! Did you mean in the last picture?

That is just the overflow pipe for the retainer that goes around the fuel cap. I assume this is there so that if you spill any diesel around the filler cap that it just drains down through the pipe and doesn't sit in the cup.

 

[BAP]

You should be able to take the rubber piece number 120 out of the cap and make sure it’s clean so that it can vent properly. Sometimes, a little bit of junk will get in between it and the cap causing it to not vent properly.

 

[GreensvilleJay]

yes, last picture.. while 030 is the 'overflow drain ?' pipe it might act as a way for venting to occour. If the cap if smaller than the 'overflow basic piece, then #120 that's inside the cap 090 may be plugged.
Your cap is similar to that on my BX23S so I'll have a look at it cause now I'm curious as to how it DOES vent . Most riders/small engines I see have a small hole in the cap and a 'rubber' valve inside but I can't recall seeing a small hole in the fill cap of the BX23S.

 

[Henro]

Sorry, I posted lots of pictures with 30s and 120s! Did you mean in the last picture?

That is just the overflow pipe for the retainer that goes around the fuel cap. I assume this is there so that if you spill any diesel around the filler cap that it just drains down through the pipe and doesn't sit in the cup.

When I make assumptions I often remind myself of the first three letters of the word assume. I’ve learned that lesson many times… I hope you solve your issue quickly.

 

[D2Cat]

The item #120 is what vents. It's failed for some reason, probably build up of dirt. Try to clean it. If nothing else solves the problem, buy a new fuel cap.

 

[DevonOrange]

OK, so this is the complete cap:

Cap with gasket (#120) taken off:

Underside of gasket. Looks like a little maze in there - this is probably the route through which the air can escape and vent:

Filler nozzle also missing thread on two sides. Maybe this lets the air vent out too?

I'll give it all a good clean and maybe solve the mystery without ASSumptions

 

[GreensvilleJay]

neat pictures..
OK, My idea is that air 'magically' vents through the 6 dark oval holes in the 1st picture.
I'm guessing air goes in them to the center of the maze where a 'rubber' valve lets air in ?
If the 6 slotted holes do lead to the center of the maze, maybe some bugs made nests in there ?
blast of air may fix it ??

this is more fun than brush painting the trailer I'm making.

 

[DevonOrange]

Spoke to the dealer and yeah, it vents through the little maze. Gave it all a good clean and will try it again. If that doesn’t work then I’ll try a new cap. I don’t think those 6 slotted holes go anywhere, but I’ll check just for good measure! Happy painting!

 

[GreensvilleJay]

hmm the air HAS to come in somewhere....maybe those 'slots' in the threads like you said ??
Surely someone has to know how....

yup, good old enamel paint and a 2" brush... goes on easy-ish and EASY to repair unlike yuk, powder coat !

 

[North Idaho Wolfman]

Yes it vent out the missing threads.