I have a Mercury hp outboard engine (1986) that will not pump water.
I installed (correctly) a new water pump and it still will not pump
water. Any ideas? Thanks! Bill

On Aug 20, 10:22 pm, The Bewley Family wrote:
I have a Mercury hp outboard engine (1986) that will not pump water.
I installed (correctly) a new water pump and it still will not pump
water. Any ideas? Thanks! Bill

Not really sure. will it pump water at idle or low rpm? did you use a
genuine mercruiser water impeller?

The reason I'm asking is because a friend of mine installed an after
market impeller that was too soft. it would pump water at low rpm, but
when wound out it would quit. found out the compound in the impeller
was too soft, and at higher revs it would literally fold back and
allow water to slip around the housing. He then installed a genuine
OEM impeller and that cured it.

I've also heard of that happening with Johnson/Evinrude outboards.

The Bewley Family wrote:
I have a Mercury hp outboard engine (1986) that will not pump water.
I installed (correctly) a new water pump and it still will not pump
water. Any ideas? Thanks! Bill
**********
Had a similar problem with my newly purchased 95 Yamaha OB. Guy I
bought it from said the impeller had been recently replaced, but on my
first time out water stopped coming out the pee hole. I thought the guy
had been lying and bought a replacement WP kit but when I took the thing
apart I found tool marks, and a perfectly good impeller.

I put a hose on the tube up into the engine and water wouldn't go
through it. Eventually I pulled off a hose from the cylinder head to
the pee hole outlet and water squirted out of it. Seems like the
channel in the gear housing was plugged up. (About a 6" channel from
the power head to the pee hole.) I managed to work a wire in from both
ends and cleared whatever was plugging it up.

Hope you're as lucky.