I had a similar problem with my ’51 25hp Evinrude. I did a complete rebuild, slipped it into the water. It started hard when it finally came to life it popped and farted something awful! After a couple WTF’s and threatening some hammer time. I calmed down and started over. It had a bad new condenser! The wires points coils and condensers were new. I replaced the whole shebang. Something to check!
dale
“get’em wet….don’t let’em set!