Mystery Spring ON F60

[plummet1]

Hi All, i am in a bit of a quandry, i am having trouble with my 2006 F60, it is spluttering and surging when i put the throttle on, it then starts to shake at tick over and cuts out
my mechanic friend suspected dirty filters in the VST, upon opening the VST, he found this spring and steel ball at the bottom of the tank, he is at a loss as to where these parts came from,would any of you knowledgeable guys have any clue, i have just ordered a new pump at his request to see will that cure the problem, but i dont think the parts are from the pump as its a sealed unit, we are confused at this point in time, any advice or help is greatly appreciated, i have attached a pic of the mystery parts

[Keithbaja]

Wow, that would be a first. Looks like the ASV anti sipon valve from top of the tank.
. I've removed ,100's of them... Problem child...one hr later edit. Without seaing or looking at what you got. I can tell you a lot of pumps have a check valve like that to hold/maintain fuel pressure.. More pics of fuel system from tank to vst

[plummet1]

Thanks Keith, I appreciate the reply, I am waiting on a pump to be delivered, I will take more pictures then as he will have the VST removed at that point, hopefully it is just the pump otherwise I could be in a bit of bother as good outboard mechanics are thin on the ground here,