35hp Johnson Seahorse - Need Some help

[k1llsw1tch]

Hi, all. I have never registered to this site but have mainly used it for research purposes. I am new to the boating world and my neighbor sold me his 16' Aluminum boat with a 35hp Johnson Seahorse with Jack Plate. I still do not understand all the lingo but bare with me here. The boat sat for almost 2 years. He stated that it ran fine before he parked it. I have two plastic 6 gallon tanks. I put new gas in it with sea foam, put it on the water and it would not idle and would just start surging as I gave it more gas. I brought it home and began breaking into the carb. When I removed the front cover to the carb (where the carb adjust needle is) I found the front facing gasket was half there. Replaced that and then bought a carb kit and replaced all he gaskets and cleaned thoroughly with gum off and air. I was astounded at how clean the carb was. Took it back to the river and tuned in the carb and i could get it to idle for a couple minutes and it would die out. I then ran it full throttle and it only feels like i am getting 20%. When i have it on muffs the thing sounds like a race engine (I learned through this site not to go high rpm's on muff's after the fact). Took it back to the river and ran it all day, fresh gas, replaced the fuel lines (internally) and i felt like i was going 10mph at full throttle. The engine doesn't event sound the way it does on muffs. I also went through 14 gallons of gas from 2 1/2 hrs of running at full throttle. Prior to all this, I did replace the spark plugs. I have no clue what i should do next. I had my dad bring his boat who has a 16' alumicraft with 90hp Johnson FI and he even stated that i was not getting the power I should be. Any help would be greatly appreciated! Thanks for providing such a great forum, I have already learned alot!

 

[F_R]

First things first. What year was your 35 made? Makes a lot of difference. Secondly, I suppose you realize by now that tearing into the carburetor was a waste of time and money, and was based on assumption. Thirdly, symptoms such as you describe are almost always caused by running on one cylinder. It could be doing that because of something as simple as a bad spark plug to an ignition system problem. Or even as bad as no compression on the missing cylinder.

So, what I am saying is do some troubleshooting before tearing into anything else. 1st on the list should always be a compression test to make sure you have something worth fixing. Follow that with an open air spark test. Expected results vary according to what year the motor is. More than likely by now you will have zeroed in on the real problem.

 

[k1llsw1tch]

Thank your for the information. It is a 1981. Do you have suggestions or a how to on the compression test or should I go with a spark plug test first since that should be the easiest?

Thanks again.

 

[flyingscott]

Do a cylinder drop test take one spark plug wire at a time off while it is running. If it stops running when you pull one off the other cylinder is not working. Find plastic pliers to do that otherwise you will get zapped.

 

[k1llsw1tch]

Flyingscott,

I did as you asked and it did indeed die when I unplugged the bottom cylinder. It did not when I unplugged the top. I take it that my top cylinder coil is bad as it has new plugs and wires? I also included a video of it running and the white smoke coming out.

 

[flyingscott]

Now you need to switch the coils around to see if the problem follows. When you switch the coils make sure you switch ALL the wires

 

[k1llsw1tch]

So I swapped the coils around and the boat won't start. Checked plugs again. Weird.

 

[k1llsw1tch]

Swapped them back and it started back up

 

[F_R]

Do you have spark on both plug wires, yes or no? My wild guess is you have two problems, a bad coil, and something wrong with the top cylinder. Could be something as simple as a bad spark plug, or as bad as a blown piston. ...OR...that missing piece of gasket could be jammed in the reeds.