Bad luck with 2 motors

Took my new to me 1980 15hp johnson out on the lake,had brought a 2008 8hp 2 stroke yamaha as a spare,,,murphys law,if something gonna go wrong it will,,,15 hp snuffed out,so whopdidoo put the 8 on and away I went,,,,8 hp died also,rowed 3 hrs to get back to base,,my guess is I forgot to put oil in the gas for the smaller engine(musta doubled up on the 15 hp tank by error) tought it was toast but an old friend of mine who used to be a small motor mecanic stuck a big screwdriver on the flywheel and got it to rotate,it works fine in a drum at the moment but the top cyl reads 140 lbs n the lower one 130,,,wonder if it will affect it a whole lot,,,the 15 hp according to the old timer was sucking air so got a new hose and fittings from the gas tank to the engine and also a new hose from gas pump to the carburator, it runs fine also(in a drum) gonna head back to the lake in 3 to 4 days since were getting high winds and rain (sucks) my main worry is how that yammie is gonna hold up with 10lbs diff between the top and bottom,,,nyway next trip Im gonna bring 3 motors, got a little 1.2 tanaka might be slow,,, but shure beats rowing. Mikey

I wouldn't sweat that 10 lb difference. Those numbers are averages and it's not that much anyways. As for your problems always look to your gas for the first source of problems. I use the ethanol gas in my Mercruiser and have for years but don't in anything with a small carb. For some reason those small passages just love to get plugged and corrode. If you do use booze gas or have to then make sure you drain the lines at the tank. Disconnect it from the tank and just let it run till it quits.
The second issue with ethanol is the lines themselves. If you leave it in there as most people do even in layup ,it will degrade your lines. The inner lining begins breaking down into almost microscopic particles that form black goo. This goo happily goes right through the filters (even the big spin ons) and deposits itself on the innards of the carb which plugs it up tight. The water wicking properties seriously promotes corrosion on the float bowl and other innards of your carbs aluminum surfaces as well. It's a good idea to replace old outboard lines with ones marked "Ethanol Resistant"., They aren't very expensive on amazon / ebay. Also consider the prior owner likely used ethanol and did leave it sitting in there right?
Soooooo, in short try to use real gas, it's not all that unavailable anymore. If you have to use booze gas, when you are finished for the day remove the fitting at the tank and let it just run till it dies assuring the lines are dry. Here is one thing an old outboard wrench told me. " If engine quits, dies ect and has spark CLEAN THE CARBS. He said he fixed about 2 to 3 "blown engine" people brought in every week by simply removing and cleaning the carbs. Carbs are the weak link in outboards in most cases.