2008 115 EFI Fourstroke - No start

[silverviper]

So my 2008 115 EFI Fourstroke Merc has been working flawlessly the last 11 years. This last Friday while putting around on the pontoon it died suddenly after having it out the day before with no issues for over an hour. Tried to restart it, to no avail. Wouldn’t even fire, just crank over. I needed a tow and then dry docked the toon.

I pulled the plugs, they were drenched in gas. First plug was full of carbon on the tip, second plug was a little cleaner, third and fourth were better yet. I cleaned them up and put them back in. Same result. I looked through the fuses, seemed to be in good shape. I checked for spark, confirmed I do indeed have spark. I pulled the fuel filters and gas dripped from them.

New plugs, fuel filters, and an air filter will be delivered this week. I am doubting these will solve the issue and I’m slightly concerned it’s the fuel pump or ECU. This weekend with the new fuel filters I plan on disconnecting the one upstream and try to start the engine and verify if gas shoots out to eliminate possibly the fuel pump. Anything else to try? Half a tank of new gas with the other half treated with Stabil last fall.

Engine # IB724895

 

[silverviper]

After troubleshooting I discovered the 4” cable inside the FSM had ruptured. I learned that the float pump switch should also be replaced as there was issues with them and a new part number indicated a revision. After the replacement the engine works like before, ran great.

However now I am having a throttle issue that I didn’t have before. The boat will slide from Neutral to the first click and start off slow, then after 5 seconds I can hear the engine rev into higher RPMs. From 1200 to 1400, and stays there. When I shift back into neutral it keeps the higher RPM. If I turn the engine off and back on the process repeats. The first “click” on the throttle forward has always been slower. Reverse works as well. When I pull up to the dock I’m coming in faster than I would like.

Is this related to the FSM troubles I was having? Did something come out of adjustment? Did I miss anything to connect?

Thanks.

 

[silverviper]

After running the boat for 2.5 hrs, and to my surprise, the boat automatically adjusted itself to the lower RPM at idle speed. Instead of cruising around at 1400 RPM it adjusted down to 700. I believe the ECU started adjusting to the new upgraded air filter, fuel filters, and float switch? I did open it up after 10 minutes when it adjusted and backed off to idle speed immediately and the engine stalled. It started up fine thereafter and I ran at idle speed and various other speeds for an hour. I then tried to get it to stall, even at wide open by shifting back to idle speed like before. No speed could make it quit. Hopefully all is good and well for awhile.