Strange water problem

[barry m]

Hi,
I have replaced a full water pump on a yamaha 75 hp 2 stroke.
This included the inner housing,so a complete new pump.

This engine refuses to start pumping water from a barrell.
When i take of the thermostat cover and back fill water with a hose into the system and replace the cover in a hurry,It will then pump away no problems.
It is driving me mad
So when i fill the system from the top it pumps away.
This engine does not seem to be able to start the pumping process.
But when it does start pumping its fine.

Has anybody got any ideas of what is going on with this engine ?

 

[dloves82]

Re: Strange water problem

Have you tried checking the pump with the boat in the water? I experienced a similar problem on my Suzuki trying to check the pump from a barrel. Turned out my barrel wasn't deep enough. The water has to be well above the cavitation plate to about the same level as if the boat were in the water otherwise the pump can't get a prime. Don't know if that's your problem but somthing to think about.

 

[barry m]

Re: Strange water problem

dloves82
Thanks for your reply.
I have been reading around the forum and doing searches and it looks like this could be my mistake ok.
The water level is just below the cavitation plate but is covering the inlets.
Have to try it out in a bigger barrell tomorrow.
Thanks again
barry...

 

[playme1979]

Re: Strange water problem

why not get a set of water ears for your boat

 

[dloves82]

Re: Strange water problem

That's the same thing I did when I was checking my pump. At least you're smart enough to come here first and ask. I took mine to a mechanic and he backed the boat down a ramp at his shop and the pump worked perfect, I felt like an idiot at the time.

 

[stylesabu]

Re: Strange water problem

MY BOAT doesn't like the muffs either,try it in the water before you go ant farther

 

[99yam40]

Re: Strange water problem

If you get the pump under the water it should pump,or muffs should provide pressure to get the impeller wet, but they do not have suction to pull water upwards unless the impeller is wet.