Originally Posted by danny
I believe that it's supposed to be as near to the tank as possible. Anyway surely before the filter.
On this topic of where the primer bulb should be - i speak not as a voice of experience but due to my rationale :-
The bulb is a pump - you squeeze it and it pushes fuel forward (the squeezing force being supplied by your hand which is relatively strong which would be more than enough force to push fuel along a long stretch of pipe or through a filter)
When you let it go however it is the elastic properties of the rubber trying to return to its natural state that pulls more fuel from the tank (this force is relatively weak so i would guess that anything that restricted this flow of fuel - ie long pipe or a filter would increase the likely hood that this weak force would not be sufficient)
Therefore i would have to agree with danny - the closer to the tank the better. because if the force required to pull fuel from the tank exceeded the force available from the rubber the bulb would collapse and effectively cut off fuel.
As i said that is not the voice of experience so there may be other reasons i have not factored in for placing the fuel primer bulb in a different position.