I never ended up changing my plugs last season, partly because I ran out of time and partly because of your suggestion...
This season I've noticed some surging on the right engine. Seems to only happen around 2000 rpm, and it surges between 2000-2500 rpm. You can feel the power changing as the RPMs change. Was initially thinking it was the fuel but have put a bunch of fuel treatment (Seafoam marine and Heet) in there and it's only happening at 2000 RPMs.
Next step to troubleshoot is to pull the plugs. Any thoughts?
These engines seem to go through plugs pretty quickly, and the FIRST order of business if an engine starts to run funny is to replace the plugs to eliminate the plugs as the issue, and for many that clears up the issue.
It appears you bought the boat used, so you don’t know how many hours are ON the plugs that are in the boat so you should change them. Be sure and gap them before you install them, and don’t over tighten them when installing them, follow the tightening instructions on the plug boxes. Buy the plugs specified in your manual.
As far as spark plug sockets go, you absolutely need to get one for spark plugs with the rubber insert, and some have a magnet at the top to provide even more purchase on the plug when removing the old ones and installing the new ones. After I pull the coil packs and the old plug is still installed, I blast compressed air down in the plug well to make sure there is no debris in there that could fall into the cylinder. When you’re changing the plugs don’t leave the plug opening without a spark plug in it for any longer than necessary….E.G. don’t pull the plugs and walk away.
Once you’re up and running go burn up the majority of the fuel that’s in the tank, I know it’s a tough task to go and drive the boat around for hours but I’m sure you can handle it
, and fill up with fresh fuel. If you have access to non ethanol fuel run that, if not just be sure to add Star Tron fuel treatment for ethanol laced fuel, and run that religiously. Use the octane of fuel specified in your manual, if it states 86 then run 87 as 86 usually can’t be found at gas stations. Contrary to what you may have been told or heard, 91 octane doesn’t have more power or make your engine run better, 91 octane has the same BTU’s as 86 does and will actually decrease performance of your engine that requires 86. Will it hurt your engine to run 91 if 87 is not available? No, just the pain in the pocket book.
In the United Staes we use PON or Pump Octane Number, so in the screen shot of your owners manual you can see the octane requirement for your boat as 86 PON. RON or research octane is used in other countries.
Don’t go ham on the fuel additives, just use as directed. Since your boat is older, you could run a tankful of fresh gas with the correct amount of Techron additive in it to clean things up. All “Top Tier” fuels have Techron in them, putting the additive in the fuel provides extra detergent to clean up piston, valve and injector deposits. Fill it up with fresh fuel with Techron and go burn a tank of fuel and enjoy your boat!
