Telltale working only when Propeller is Off!

[Jura Jock]

Anyone heard of the above issue on an older 2.2hp Mercury at all? No prop on and the water is squirting through telltale perfectly.....put Prop back on and dry as a bone,nothing coming through. So obviously water intake, impeller and circulating pipes running fine. Any history on this from guys with a small mercury ?

[jeffstevens763@g]

My 3.3 pees with the prop on not the best pressure but it’s only an indicator

[Jura Jock]

cheers for that,but engine block heats up so cant risk it even though i know water flows with prop off!