Checking your water pump.

Details:

We recommend using a water filter before your pump as it's possible to pick up a gum nut or other objects which may instantly destroy the impeller.

Any extra fittings installed before the pump for flushing the engine must be airproof or this will impede the suction.It's not recommended to run your engine longer than 10 seconds without water going through the pump.

Method of checking
A simple test any owner could do is fill up a bucket of water and with the boat on the trailer sit the bucket on the ground, connect a hose to pickup line insuring airtight connection, start your engine and the pump should start sucking water from the bucket.
If this doesn't happen you may wish to pressure feed a bit of water to expel air from the line to hasten suction.
If suction still doesn't occur then maintenance is required.
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If you are feeding water direct to the waterpump with a hose from a mains pressure supply we advise to fit a tee fitting in the line near the pump and from it run a piece of hose back over the side of the boat and waste the water and in doing this you are not pressurizing the pump and motor as the pump is designed to draw its own water in. If you do not use this setup you would be forcing water in up to 70 or 80psi. and the gaskets in the engine may not maintain a seal.

Out on the water you can check the water pump condition by with the motor running you should be able to run the palm of your hand along the side of your water-cooled manifolds without burning your hand. If the pump is requiring attention or a blockage the manifolds will get the hottest at idle revs as the pump is not getting assisted with water pressure as the case at speed.

A sign of a pump in need of attention is when a boat accelerates away and after a few seconds you notice a drop in engine noise as it is water through the exhaust pipes that has a factor in noise control.

If you are running a cam driven water pump you should be alert of any engine oil discoloration as water can get forced through the pump seals if they are in need of replacement or to much water pressure at speed.
The life of an impeller could be from 5 minutes to 5 years all depending on care and the situation it is used under.

Warning
If at any time you find parts of the impeller broken off and missing it is common for these pieces to become lodged in water fittings and therefore impede water flow after the replacement impeller has been fitted.

The above info is only personal views put forward to assist ski
boat owners from Bob at R & M Precision Marine