Reply To: 1960 Evinrude Fisherman stalling

[JACQUES]

External pumps work by getting a pressure pulse. Since on a pre-60 engine  both crankcase  provide a pressure pulse  and each pulse is kept separate by the flapper valves….. allows air pressure to exit via the  nipple and pressurize  the  2 line  fuel tank.  Hand priming only serves to fill the carb so theengine can run a few minutes to pressurize the tank to force fuel back up the fuel side hose !

To run an external pump  using a sinlgle line hose one crankcase chamber’s downstroke pressure  is used hence the need to block out one channel otherwise the pressurized air would uturn into the other crankcase  half section .

The accepted notion  here is that gluing up one channel as per the viedo impairs the ability of the crankcase’s accumulated fuel-oil to be dumped out the purge valve. This juice can be  burnt off with WOT runs to create   in flow turbulance  in the   now  ” sealed” crankcase.

Using rubber caps like in the video allows proper drainage  of fuel oil residue and is probabaly the best way to go.

All this to say some  do like two line operation .

 

here is an interesting article of  keeping sludge out of the lakes

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