redsinthehead
New member
I have a 2000 Yamaha 50 hp 4 stroke that is driving me nuts. Have done everything I know to do... Cold start, it cranks no problem but sounds funny. Runs for a few minutes then RPM's slowly drop and stalls. Won't crank again without raising warm-up lever. Once I get it running again, still sounds strange. Pull #2 and #3 plug wires - no change in motor. Pull #1 or #4 and it stalls - assuming it's running on only two cylinders? Loud popping from spark as I pull and replace plug wires..., mechanic checked spark and it shows good - new plugs don't help... Have rebuilt the carbs (BIG $'s), used alternate gas tank...., mechanic works on it - pulls, flushes and adjust carbs and it runs great for one or two trips, then right back to same problem...has done this several times - fortunately mechanic is a good friend and Yamaha mechanic of 26 years (free labor) - but whipping him... yes I use gas with ethanol, but use stabil ALL the time.... carbs look clean when disassembled?? I baby this rig, garage kept, bought new, LOOKS new..... I have heard Yamaha has always had trouble with this carb set up - anyone heard that? I have had the motor for 12 -13 years and it has always run a little funky, but lately so bad I can't even use it.