Fuel tank vacuum lock

[Big mick]

G'day all

Question for you all, if you fuel tank breather is blocked and the fuel won't flow is that enough to course the bike to run lean and damage internal parts

[William1]

With a 2s, possibly, doubtful it would hurt a 4S.

You do realize, the bike will run poorer and poorer and eventually stall from fuel starvation.

[Big mick]

With a 2s, possibly, doubtful it would hurt a 4S.
You do realize, the bike will run poorer and poorer and eventually stall from fuel starvation.

I'm sure the bike would stall eventually but if the bowl isn't filling quick enough the bike will idle but run lean on full throttle due to the lack of fuel available

[OLHILLBILLY]

Like William1 said, if it's blocked enough to pull a vacuum on the tank, the bike will run out of fuel and die, like when you forget to turn the petcock back on. There is a very thin line with most bikes as to how much fuel in the float bowl is required for it to run or not. My YZ has about a 3mm float height range between flooding and not running, if the fuel flow is restricted to the point of not allowing enough into the carb to maintain float height, it's not going to run for very long before just shutting off and making you wait until the float bowl fills enough to restart the bike. It will cause a momentary lean condition before the motor stops, but not enough to damage the it.