I have a 2002 90hp Johnson motor on my pontoon boat that is intermittently getting too much fuel regardless of speed or rpms -- it does idle fine. I would describe it as a jerking motion that is cutting out. The best way to describe it is "intermittent" since it will drive fine for 15-20 minutes and then act like something is telling it to increase fuel and then it runs rich for sometimes a few seconds and other times a few minutes then go back to running good again. Sometimes it's so bad it seems like it will completely flood out and other times its mild and just irritating. One day it drove great even when pulling tubers and moving around with only 1 hesitation. The next day it was back to frequently having problems again. From what the previous owner stated, it sat for a couple of years so we thought it was "bad gas" causing the problem. When it acts up, it smells like gas and on the worse episodes I get bad gas mileage. I have taken it to the best outboard motor mechanic in my area who, through the process of elimination, is ruling out things to try and diagnose the problem. He started with the basics since it seemed to be a fuel issue: filters, cleaned carbs., changed air syphon valve, checked fuel pressure throughout motor, hooked up alternative gas supply and ran, etc. --- nothing changed. Then moved on to checking all wire connections/grounds, changed plugs and other electrical type things I don't fully understand. He was going to research the problem over the weekend and I'm taking it back to him to move on to other possibilities through process of elimination. Any other suggestions?
