1996 johnson 112 power loss and failing spark plugs.

[doityourselfer1]

After our last trip on the intercoastal waterways runing around for about 2 hours the engine was working flowlessly.we anchored for 10 minutes to fish and decided to go home anyway since the wind was cold and we where freezing.started the engine took off the boat almost plained out and quickly was loosing power. Just barely made it back to the boat ducks in idle speed. After i got home i found the#1 spark plug was badly kind of burned,and inside the sparkplug there was tiny pieces of melted aluminum chunks lodged in. I performed compression test,and all 4 cylinders 105 to 110 psi. I figured this is ok for a 1996 engine. The boat has brand new fuel lines,new racer filter with water separator, new sparkplugs again,new powerpack,timing was checked twice with timing lite. Checks out ok.pickup timing on idle is at 4 and wot timing is at 28 btdc. Just like the manual tells me.i tested the rectifier with a ohm meter folloving the instructions in the manual,and getting low readings on all connections. I am not familiar with the ohm meter , not sure i am testing it correctly, but suspecting a bad rectifier.the carbs where just taking a part and double checked, rebuilt the fuelpump too. I am runing out of ideas here. Sparkplugs always gapped at 0.30 inches, the another thing i suspecting here is when i purchased the boat 3 months ago it looked like set for a while. The boat came with a half of tank of gas in it . I jut topped it off with fresh 93 octain. Used johnson 2 stroke oil to pre mix to 50 to 1 mix.the engine runs like a champ on the hose with earmuffs and starts the first time. After all this work it is still acting up when in the water under load!! Could be old fuel? Or bad rectifier ? I dont know any more.i purchased a 6 gallon portable gastank put fresh fuel to 32 to1 mix this time to give it some extra lubrication. Going out to the local lake to test this sunday just to rule out the old fuel problem. Any ideas?can anyone help please?? All inputs are appreciated . Thanks. Robert.

 

[dieselcat]

Re: 1996 johnson 112 power loss and failing spark plugs.

im no expert but i would try a decarb before going any further.get 1 gal of 50:1 gas and mix a whole bottle of sea foam with it also.run the entire gal of mixed gas with sea foam through motor,it will smoke due to sea foam but sometimes it works wonders,especialy if there is carbon build up in motor.hope this helps good day and best of luck...

 

[seahorse5]

Re: 1996 johnson 112 power loss and failing spark plugs.

IF those were aluminum pieces on the sparkplug, the piston is starting to come apart from detonation. Pull the cylinderhead and inspect everything closely before something happens that is expensive and/or leaves you stranded on the water.

 

[emdsapmgr]

Re: 1996 johnson 112 power loss and failing spark plugs.

You could have residual water in the fuel tank from the original fuel. Not only does it affect the engine performance, but may also affect lubrication of the rotating assemblies. For peace of mind, I'd pump some out via the (engine) fuel hose into a large, clear water glass. Let it sit for 15 minutes and check for water. If you don't want to pull the head to check for aluminium, remove the spark plug and shine a pencil light inside to make your visual inspection. Aluminum debris on the plug tip is usually not good news.

 

[boobie]

Re: 1996 johnson 112 power loss and failing spark plugs.

The first thing I would do is find out why you had aluminum on the spark plug before running it any longer.