Reply To: 1957 johnson 18hp fuel mixture

[duralark]

Wow… MANY thanks to all who have responded re my no-start AD-12!

I hadn’t had the flywheel off this one before, but had looked thru the adjuster hole, and everything looked nice, for what that’s worth — green coils, shiny newer-looking condensers, etc and it ran well, so that was that. This time around, I decided to renew everything including the plug wires. The only visible problem was that the points had been installed without benefit of cam lube, so the rubbing blocks were almost completely worn away, retarding timing of course. All is new and proper now, but regardless of how good the ignition is, there is no air-fuel mixture getting through the reeds, and the plugs remain completely dry after 25 pulls with the choke closed. Pumping up the tank will fill the sediment bowl, and 4 or 5 more strokes will result in a firm tank plunger as the inlet valve closes. Removing the high speed jet will result in a few oz of fuel running out, verifying that carb bowl is filling, too.

All the gaskets in the intake tract are good, no evidence of any leakage there. Mention was made of possible air leaks at crankshaft seals, but a) I can’t see any such seals in the exploded parts diagrams and b) there’s no evidence of anything leaking OUT at either end of the crank, so I don’t know what to think. The compression is strong and even too.

There was a slight amount of corrosion/buildup on the reed plate so I smoothed it all off with some 400 sandpaper and will reassemble with new reeds in a few days and report back. Thank you all again!

Duralark