Merc 50 HP 2005-Power Loss

[fishyree]

I hear a lot of boats are being affected by Ethanol Gas. I've limped back to the ramp twice this week. After the first time, I took some advice and used a can of Seafoam in the remaining 12 or so gallons in my tank. I replaced the fuel/water seperating filter and the plugs. Checked all my wires carefully. Motor has less than 30 Hrs on it (Like new)
Yesterday was the second day. It ran perfectly out of Matapeake for a mile and then started to sputter and lose power. The motor will not stall but will not accelerate over 3000RPM at full throttle. Occasionally, it surges and regains power for a moment or two. I even sprayed seafoam and throttle cleaner directly into carbs and it still didn't seem to help. I'm at a loss. I feel like a read somewhere about a HIGH SPEED MODULE that's easily replaced. There were no obvious signs of water when I changed the fuel filter.
I'm trying to avoid the inevitable $200.00 + trip to the boat doctor.

Any thoughts are appreciated. Any great free lance technicians on or near Kent Island with Merc Outboard Experience--PLEASE HELP!!! I'll take you fishing!!!!:helpsmilie:

[Bob H.]

Not much of a description to go on for day 1. The switch module failure usually shows up once the engine is warm and the heat has had to soak into the module. Since the two days can't be compared from your description it's probably still a fuel problem. There's also no mention of how long the boat has been unused and an whether or not it's E10 in the tank or a mix of MTBE and E10. Pull the carb bowl and see what's inside. Take a spare gas tank with a gallon of gas a dump in a can of Seafoam. Run the off the spare tank and see what happens.

[bottom scratcher]

If the engine doesn't surge at lower RPMs, I would suspect water in the fuel. As for not getting full throttle, it sounds as though you have clogged high speed jets. I'm taking that you have a 2 stroke 50 hp. At the base of each carb on the side is a plug that unscrews. If you remove it you can remove (carefully) the high speed jet behind it with a screwdriver. Clean it with compressed air. Hopefully, you also have a 10 micron fuel/water separator. I know a lot of Merc dealers say not to install it but I wonder if it's said for job security. We have a few 50 hp Mercs at work and had similar issues until I installed the separator. I also put 3 ounces of Startron into the separator and into a six gallon tank and cleaned out the system. I haven't had an issue since. Good luck.