Evinrude outboard motor repair?

1986 Evinrude 90 Shes running really rough?

• evinrude outboard motor repair Evinrude 90 trying to get to run right some help Please.. runs real rough and backfire 86 Evinrude 90 just purchased cheap and I don'want't to throw good money after bad any help would be greatly appreciated. owner said ran good till it sat. I'm more of a part changer than a mechanic but I do have the manual and did stay at a HowarJohnson'sns LOL Ok It had no spark on thPort sidede was running on 2 cylinders. When I moved power Pack to left side It had Spark so I ordered a new one from here and some carb kits . I put te power pack on tonight and It has spark on all four cylinders. I put a new set of plugs in it and fresh fuel . started it up still runs rough and left plugs seem much cooler she backfires runs rough and shakes. So I figured I'd give it a compression test results as followPort sidede top =80 bottom=83 Starboard top=70 bottom =70 low but they don't seem that far off from each other. So what's the next move Carbs? Timing? I'm getting lil Stumped any suggestions welcome

• Answer:

  Try one more thing. Pick any one cylinder and hook your spark tester in line with that cylinder then start the engine.......then do the same one at a time for the other cylinders. (If you have an rpm gauge watch what happens) This is a poor mans Cylinder Shorting test, but be careful that you set everything up correctly, so you will not blow your new pulse pack. Hook your timing light to each of the four spark plugs one at a time and watch for intermittent firing. Pull the flywheel and see if the key is sheared? These motors don't like to sit with fuel in them for any length of time. You can soak the rings with Marvel Mystery Oil and that might free them up. Just pull the plugs and squirt a lot in and let it sit for a couple days. Tilt the motor up and do one cylinder at a time, rotating the piston it to TDC. OMC tune up in a can is pretty good also. It can't hurt to rebuild the carbs...... and take a look at the reed valves while the carbs are off. If I had it in my shop, I'd just tare it down and make sure the crank and pistons where in very good condition. I'd rebuild the carbs and put the tester on the ignition system.