Re: Mercury outboard not peeing.

[Ron Devries]

The impeller may be the problem, even though it looks OK. The tips of the vanes must contact the outer edge all the way around. If the tip separates from the pump wall, even just a tiny bit, it will not pump properly. As the little chamber gets smaller to force the water up the tube, enough slips through the gap into the next chamber that it doesn’t build any pressure.