Fuel tank breather blocked

My ‘07 RTP requires that the filler cap is opened every fifty miles or so to release a vacuum. The rubber pipe on top of the fuel pump assembly is clear and it's plastic spigot won't let me push anything through it

There is no charcoal cannister on this bike so short of replacing the whole and expensive FPA can any one suggest a way forward?

ps. if I let the fuel level fall too low the sides of the tank collapse pushing the base outwards which in turn interferes with the left stanchion and low speed steering

My ‘07 RTP requires that the filler cap is opened every fifty miles or so to release a vacuum. The rubber pipe on top of the fuel pump assembly is clear and it's plastic spigot won't let me push anything through it

 

There is no charcoal cannister on this bike so short of replacing the whole and expensive FPA can any one suggest a way forward?

 

ps. if I let the fuel level fall too low the sides of the tank collapse pushing the base outwards which in turn interferes with the left stanchion and low speed steering

Morning Kritou

How was the tank vented to atmosphere after the charcoal canister was removed?

The tank vents from the TOP of the tank through the safety valve (not through the fuel pump pass through).

If the tank vent hose is open and connected and is NOT BLOCKED or PINCHED then your problem is probably in the tank-top safety valve (you might have to remove that & make sure that it isn't blocked with varnish or crud.

Also verify that the exit vent hose from the tank-top safety valve is open & not blocked or pinched.

There is some sort of roll-over vent-shut-off in the tank top safety valve (probably a ball or spring loaded ball but I haven't ever had one apart to look inside).

Thanks DR - would it be correct to say that your blue arrows could be drawn round the other way to allow atmospheric pressure in, and would it be OK to attach a bicycle pump to the tank venting line to blow through the safety valve?

As I understand it, it was only bikes intended for the North American market that had canisters fitted - so my authority bike never had one

Thanks DR - would it be correct to say that your blue arrows could be drawn round the other way to allow atmospheric pressure in, and would it be OK to attach a bicycle pump to the tank venting line to blow through the safety valve?

 

As I understand it, it was only bikes intended for the North American market that had canisters fitted - so my authority bike never had one

Morning Kritou

Yes, the venting can go both ways with probably the air-in direction being restriction free & the "venting" (overpressure-out) being held at a positive pressure slightly above atmosphere for emission concerns.

You are probably better off using your mouth to blow in through the end of vent hose then listening for air coming out the open filler cap. (air flow IN should flow pretty restriction free but air out might have some resistance or restriction)