Hello,looking for some help.i have a johnson 70hp model J70ELCSA think its 1980's?.starts fine but is flooding itself.i can start it no problem but if i turn it off it wont start again as its flooded.when i pump the primer it holds pressure but when i turn key to restart and it seeps fuel out of all the carbs.if i disconnected the fuel and let it alone it clears and starts again so i reconnect petrol.but if i turn it off this happens.it makes it unreliable hence usless.is this a small problem or what.help greatly appreciated