115 Johnson Stalling as soon as dropped in water

[mzescamilla]

Guys, I have a 1992 Johnson, 4 cyl. The engine looks very clean. I have replaced filters, spark plugs and did a carb kit. When I start it out of the water, with a water hose attached, it starts like a match. The problems begin when you take it to the bay. It will crank great outside the water, but it will give you a hard time to start once you place the lower unit in the water. Sometimes when you finally get it running, it will run great and all of the sudden it will bogg down and maybe die on you. I am a rookie boater but a good auto mechanic. please advise. Thanks to all you guys.

 

[R.Johnson]

Re: 115 Johnson Stalling as soon as dropped in water

When the engines bogs down and stops,pull all 4 spark plugs, and have someone crank the engine over and see if there is any water vapor coming out of any of the plug holes. Ground the plug wires when you do this. I am not in the shop right now, and don't have the service manual in front of me. Does this engine have the bolt on exhaust cover? You could have a water leak there, or around a head gasket. You could have a blockage in the exhaust passage such as the engine setting to low on the boat and releif holes are covered.

 

[K Hultgre]

Re: 115 Johnson Stalling as soon as dropped in water

With the muffs on the engine at home it will start and run perfectly for 15min, correct?<br />If you could use the muffs at the boat launch (boat out of the water) it would start and run the same as at home, correct?<br />Now if you put the boat in the water (saltwater?) the motor will give you a hard time, correct?<br /><br />Have you tried backing the boat down the ramp so just the lower unit water pickup is in the water not the whole boat or even a majority of the transom.<br />I'm thinking you are having a electrical problem that will only show up when a certain part is below the water line. Something like your "Trim and Tilt" motor/connection. Or something like galvanic action if in saltwater creating a voltage between the motor and something like the zinc anode causing the ignition to misbehave. <br /><br />Good luck, my $.02

 

[AUGIDAWG]

Re: 115 Johnson Stalling as soon as dropped in water

Your engine will run lean on the muffs.<br />If it runs great on the muffs, then your engine set-up is too rich.<br />When you put it in the water, you get more back pressure on the exhaust, causing it to run richer.<br />If it is too rich, it will foul the plugs and run poorly.<br />Also, with no back pressure, it will idle very high. If the idle timing screw was set with it running on the muffs, then it will be way too retarded in the water.<br /><br />I don't buy the galvanic action stuff.

 

[K Hultgre]

Re: 115 Johnson Stalling as soon as dropped in water

After rereading the original post about the carbs being rebuilt I think Augidawg is more on target. But I have seen some strange electrical and mechanical problems arise only when the boat is in the water.

 

[james roach]

Re: 115 Johnson Stalling as soon as dropped in water

Could we possibly be overlooking the obvious. The idle maybe set to low. I have run into this before. Before you start replacing parts just check this in the water. Good Luck

 

[AUGIDAWG]

Re: 115 Johnson Stalling as soon as dropped in water

That is what I meant about the idle timing being adjusted while on the muffs. I bet that's what is happening.

 

[Melvin Hatcher]

Re: 115 Johnson Stalling as soon as dropped in water

Not being a boat mechanic but, a fair auto mechanic myself.<br />I have learned to really pay attention to the carb linkage snyc and cam follower adjustment. <br />These darn things will not idle worth a darn if the carbs are not fully close at idle.