70hp 2 stroke yamaha question

[jwclbi]

So I have a very good running clean 70 yami on a whaler, the problem is it is very very difficult or impossible to get it to take the initial prime of fuel. I squeeze the primer ball and after 4-5 squeezes the primer ball is hard, normal. Engine won't fire. Pick up the primer and feels soft again. Prime some more (a lot actually) and now the primer ball won't fill and get real firm, but not flat soft either. So I put some gas in 2 of the 3 carbs and she fires right off and runs flawlessly. Ive checked all the fittings and swapped out the primer ball. Fuel pump looked fine when I opened it up, as well the little filter on the engine is clean. Any thoughts? Thanks