Intermittent running. Sometimes she will start and run, sometimes she refuses to fire other than an occasional backfire through the carb. Lately it won't start at all. I've rebuilt the carb as it had some leaks. Electrically I pulled the plug to check for spark... grounded it to the exhaust pipe and cranked her over. Sometimes a weak yellow spark, sometimes a strong blue spark, sometimes none at all. Seems to come and go. Weird to me. You guys have any ideas on where to start, or have seen this before? Starting fluid doesn't help, won't fire at all when it has decided it won't run.
