help with 93 johnson 90hp

[weekend boater]

I have a 93 90hp johnson. Have had some difficulty getting it to warm up properly. Takes a few trys to keep it going. 2 weeks ago, the motor just stopped running on a full run back from a fishing spot. Couldnot restart, just fished for a bit. Changed the plugs on the spot. After about 10 mins of cranking, got it going. Ran for about a mile and then quit again. Fished for a little bit and tried to restart. Got it going in fast idle but would die when engaging in gear. Did get home to the dock.<br /><br />Week later, checked spark on all 4 cylinders, okay there. Took about 4 tries to start but got it started in the driveway(earmuffs on the motor). Ran a little ruff.<br /><br />Went to a couple of shops for compression test. Top 2 cylinders read 110 psi.<br />bottom left averaged around 80 psi. bottom right averaged 85 psi. Both places said i need to have the power head rebuilt(1500 to 2500). <br /><br />Just talked to another shop today. Mentioned that the top ring could be sticking and allowing blowthru. Said to take the omc engine decarbonizer, spray the bottom 2 cylinders, let soak overnight. Fire up motor and decarbonize the motor with the rest of the can. Then take new set of compression readings. If they read in the normal range should be okay.<br /><br />I understand some of this. But could this last guy be right about the rings sticking or do I have other problem with this?<br /><br />Any help would be appreciated.<br /><br />Just got the boat this summer.<br /><br />thanks.<br /><br />I

 

[Dhadley]

Re: help with 93 johnson 90hp

DO NOT let the engine tuner sit in it overnight. Follow the instructions on the can. I usually fog the engine and let it sit for 1 to 2 hours and then run it long enough to get the tuner out. If it helps then you can always do it again. But NEVER leave the tuner in the motor longer than 4 hours.<br /><br />It's kinda hard to believe they called for a rebuild without pulling the heads. You can do so to inspect the walls (and check out the deflectors while you are there). The bottom carb may need some attention no matter what.<br /><br />By the way -- it's gonna be the bottom ring that stucks first from carbon. <br /><br />It doesn't sound good but here's hoping the tuner does the trick -- Good luck!