Ongoing saga 84 85hp low rpm at wot

[84force]

Thanks for a great forum to discuss force outboards! I have a continuing battle on my hands in the form of an outboard that will not reach the proper rpm at wot. I can only reach 3200-3500 rpm. I have checked all the usual things including: throttle plate open and level, compression 130psi all cylinders,timing, fuel pump, line,vent, linkage. Most recently I did a decarb on the engine both liquid and spray, seafoam brand. This increased my acceleration but did nothing for my rpm or top speed. I have tried both a 17 and a 22 pitch prop with almost the same results. Last evning I discovered a burnt spark plug boot on #3. I am planning on repairing the problem this evening. Is this an indication of a coil problem and if so how do I test the coils? Any ideas or suggestions would be great. Thanks

 

[eurolarva]

Re: Ongoing saga 84 85hp low rpm at wot

Could be an indicator of a bad plug wire and it was arching. Test for spark in that unit and if you can just replace the plug wire do that first then re test spark. If you can watch the motor with the cowling off while it is running in a dark area with muffs or in a tub of water you can look to see if there is arcing somewhere. Your low RPMs could very easily be a missing cylinder.

 

[84force]

Re: Ongoing saga 84 85hp low rpm at wot

Could be an indicator of a bad plug wire and it was arching. Test for spark in that unit and if you can just replace the plug wire do that first then re test spark. If you can watch the motor with the cowling off while it is running in a dark area with muffs or in a tub of water you can look to see if there is arcing somewhere. Your low RPMs could very easily be a missing cylinder.

Thank you for the tip. Did not have a chance to work on it last nite, will try again soon.