I bought a 1984 CVX-20 with a 1977 Evinrude 200hp. I have been working on it non-stop to try to get it in prime condition. Keep in mind that I am new to boat engines.<br /><br />I was having a gas issue where at WOT the engine would die. I pulled the tank and there was all kinds of gunk in it. Verified this was the problem by hooking it up to a 6 gallon tank directly.<br /><br />Decided I should decarb using SeaFoam, so I put the muffs on was in the decarbing process when I heard the overheat warning horn come on. I immediately shut the engine down. My Hose stopped pumping as it is connected to my sprinkler system pump which burned up while I was doing this. I know it ran between 30 seconds and possibly upto 2 minutes without water. <br /><br />After cool down, engine started up fine and sounds fine. I took it to the river and it seemed like I had lost some low end power, and high end Max RPMS were around 4000-4200. Now there are two issues first off I put a new 21" prop on because the 19" that was on there was banged up. Secondly considering I only ran it that one time at WOT with the 6 gallon tank I don't really remember what my Max RPMS were. I am sure the prop was part of the power loss. But I would think I should easily be able to turn a 21" with my setup.<br /><br />Some questions:<br />Should I replace the impeller? It was brand new 2 days old before the overheat.<br /><br />Shouldn't I be able to turn a 21" prop?<br /><br />What might I have damaged from the overheat?<br /><br />How do I check for spark?<br /><br />The engine sat for over a year with out being run do I really need to rip the carbs apart. I would prefer not to mess with them. <br /><br />What type of spark plugs should I be using? The type that were in there didn't match factory #'s.<br /><br />Sorry for the long post, but I really appreciate the help.
