What to look for Johnson 9.9 Model#E10RL4EE

I am looking for a kicker, preferably a four stroke. Anyway, a private seller has this motor for sale, it's a Evinrude 9.9HP Model#E10RL4EE. The problem is it starts and idles fine on muffs. When on the lake "it seems to get back pressure when in the water and hard to start". The seller thinks the carb needs rebuilt, and it doesn't sound like he's even addressed the carb. I am thinking about looking at the motor. I guess the first thing I will do is check the compression, and go from there. What other things should I be paying attention too? Or should i just run. Thanks, Dave

"It's allways the carb"

OR

"Its always the black box"

Why, oh why, do people thiink that way?

At least you are thinking sensibly, begin with a compression test.

Or run.

I do not think back pressure comes into the picture as much on a 4 stroke.-----There are known issues ( rockers arms ) with these 4 strokes.-------Ask your local dealer about service on them.-------Check out price of parts / availability of said parts.-----Nice when they run and are properly looked after !!

Lol! The seller said that he was “quite certain the compression is ok”. FWIW. It’s always a dirty carb, just like when looking for a used car. Everything is great, the engine light is only on because of a bad O2 sensor. That is until you put a cheap OBD tool on it and pull two dozen codes.

Right. O2 sensors are a common failure, as are carbs on seasonal equipment. A compression and spark test are good starting points. Look for any evidence of overheating, like melting of any parts around the " business end" of the powerhead. If the owner has used ethanol fuel, then it could need a carb rebuild. I agree with my peers, a backpressure situation is only aggravating another problem. On any 4 stroke, some backpressure is helpful for a variety of reasons, but too much, of course, will cause loss of power, economy, and potential overheating. The additional pressure produced by the water is going to be minimal and likely not cause hard starting in your case.

I would say back pressure has a MUCH greater effect on a 2 stroke.-----On a 4 stroke the spent gasses are pumped out by the piston.-----Not so on a 2 stroke.-----I have 3 of these 4 strokes.----Picked one of them up when dealer said " was run without oil " so $100 its yours.-------Do not know if there was no oil in the lower unit or no oil in the sump.-----Just parts it was worth that and more.

Thanks for all of the input. With all of your info, I think I'll pass on this one and keep looking.