Boat trouble: Had the boat out yesterday was running good on the way back to the ramp it slowed to about 3/4 speed and when I slowed down it started missing only running on one...

Wv mike Loc: Parkersburg area. Wv

Had the boat out yesterday was running good on the way back to the ramp it slowed to about 3/4 speed and when I slowed down it started missing only running on one cylinder. Going to start with the plugs 🤞probably the shop after that.

Fredfish Loc: Prospect CT.

Wv mike wrote:

Had the boat out yesterday was running good on the way back to the ramp it slowed to about 3/4 speed and when I slowed down it started missing only running on one cylinder. Going to start with the plugs 🤞probably the shop after that.

Is it a 2stroke or 4stroke Mike? If it's a 2stroke, definitely start with the plugs. Next thing I'd check is the fuel filter, or for water in the fuel. Good luck buddy, and let us know how you make out.

Whitey Loc: Southeast ohio

Wv mike wrote:

Had the boat out yesterday was running good on the way back to the ramp it slowed to about 3/4 speed and when I slowed down it started missing only running on one cylinder. Going to start with the plugs 🤞probably the shop after that.

I hope it's something simple like a plug Mike. Good luck buddy 👍

Wv mike Loc: Parkersburg area. Wv

2 stroke. 35 hp mercury around a 1985 model

OJdidit Loc: Oak Creek Wisconsin

Fred is right on the money, start with the easy stuff as it may be a simple fix. Good luck!

Blackdog Loc: Round Rock, TX

Fredfish wrote:

Is it a 2stroke or 4stroke Mike? If it's a 2stroke, definitely start with the plugs. Next thing I'd check is the fuel filter, or for water in the fuel. Good luck buddy, and let us know how you make out.

That's exactly what I thought. Sounds like water in the fuel or not getting enough air. Since I don't know diddly Squat about boat engines, I waited to see what you guys thought.

Good Luck Mike.
Keep us posted.

BD

Fredfish Loc: Prospect CT.

Wv mike wrote:

2 stroke. 35 hp mercury around a 1985 model

2 strokes have a tendency to foul plugs, even the surface gap ones, so that's the best place to start. Good luck buddy.

Loveatightline Loc: Nv

Everyone is spot on ,air,fuel,spark. After that it gets expensive.
Good luck and hoping for a quick fix.

DozerDave Loc: Port Orchard Wa.

Fredfish wrote:

Is it a 2stroke or 4stroke Mike? If it's a 2stroke, definitely start with the plugs. Next thing I'd check is the fuel filter, or for water in the fuel. Good luck buddy, and let us know how you make out.

Check the plug wires, also. I wouldn’t think that you would foul a plug running under full throttle. Something happened in route back to the ramp. Could be a fuel supply issue…

🐟on

Fredfish Loc: Prospect CT.

DozerDave wrote:

Check the plug wires, also. I wouldn’t think that you would foul a plug running under full throttle. Something happened in route back to the ramp. Could be a fuel supply issue…

🐟on

I've had them foul while cruising before, once the carbon build-up bridges the gap. I've gotten into the habit of cleaning mine at mid season.

DozerDave Loc: Port Orchard Wa.

Fredfish wrote:

I've had them foul while cruising before, once the carbon build-up bridges the gap. I've gotten into the habit of cleaning mine at mid season.

Yes, I was thinking more along the lines of an oil/wet fouling …

🐟on

Fredfish Loc: Prospect CT.

DozerDave wrote:

Yes, I was thinking more along the lines of an oil/wet fouling …

🐟on

The older, premixing 2 strokes use a compromise oil/gas ratio. My 1990 is 50:1 , and my 1971 was 20:1 . The fixed ratio isn't ideal for all rpms, that's why they came out with oil injection, to vary the ratio. If you run lower rpms a lot they tend to get carbon build-up quicker.

DozerDave Loc: Port Orchard Wa.

Fredfish wrote:

The older, premixing 2 strokes use a compromise oil/gas ratio. My 1990 is 50:1 , and my 1971 was 20:1 . The fixed ratio isn't ideal for all rpms, that's why they came out with oil injection, to vary the ratio. If you run lower rpms a lot they tend to get carbon build-up quicker.

🐟on

Grizzly 17 Loc: South central Pa

Wv mike wrote:

Had the boat out yesterday was running good on the way back to the ramp it slowed to about 3/4 speed and when I slowed down it started missing only running on one cylinder. Going to start with the plugs 🤞probably the shop after that.

Mike I had fuel line collapse on me one time. It was rubber with a liner.
👍

1Oldboat42 Loc: Kearney, Nebraska

Wv mike wrote:

Had the boat out yesterday was running good on the way back to the ramp it slowed to about 3/4 speed and when I slowed down it started missing only running on one cylinder. Going to start with the plugs 🤞probably the shop after that.

My '93 Johnson did that last spring (2022) and it ended up being the motor was shot. So $4000 later with a new power head all is good again. That was "cheeper" than a new $12,000 motor. I now mix t fuel after doing away with the oil injector and check and clean the plugs every week.