Help with 1988 Johnson 25!!

I just bought a new to me 88 johnson 25. I took it to Lake Michigan today for her maiden voyage. The motor runs fantastic. 125 psi compression in both cylinders. Takes of like a monster on my 1440 Lowe, and tops out (in VERY high waves at 28 mph). The thing is, after running a few miles and coming to an idle the motor smokes pretty bad. At first it appeared to be steam, but when I got to a non windy area I could see the smoke in the sunlight and it was blue. Last owner replaced he impeller last year. Spots water out of midsection in rear and pisses water good out of the tell tale.

Water from tell tale is pretty warm, but I can keep my hand in the flow. Head is hot after run but once idling the pump seems to cool it down. Also, after idling a while the tell tale water becomes cool.

When I got home I pulled both plugs. Both plugs and cylinders had what appeared to be oil and fuel in them. I stuck a paper towel in one and it smelled and appeared to be only fuel and oil.

So here is my question, am I just running my fuel oil too rich? I have it mixed for 50:1. Or could it be an over fueling issue at idle? I was playing with the idle air fuel knob and set it to 1.5 turns out from lightly seated. Or is it over heating? My 15 up evinrude would pee cool water all the time from the tell tale. I just don't want to burn up my motor!

I'm not a mechanic but I don't see/read any problems with your outboard. If you can put your hand in the pee stream and keep it there, its normally a good indication that the motor isnt overheating. Older 2 strokes due tend to smoke at idle and perhaps your alittle heavy on the oil, this tank? All your numbers look great to me; happy boating.

What oil did you use? the penzoil semi-synthetic I use burns very clean-little smoke for old two strokes.

I was thinking everything was ok, however I have never had a motor smoke so bad. I run the evinrude red two stroke oil. I am thinking I may be running too rich (air fuel ratio), possibly the reason why when I pulled the plugs there was a puddle of fuel and water in the cyl?

When at idle I adjusted the idle air knob all the way from closed to 1.5 turns out. There seemed to be no difference is smoke even after turning the knob to say .5 turns from fully seated. I may pull the carb and give it a thorough cleaning.

Also, I was watching videos of other johnson evinrude a running and non smoked as bad as mine.

The fuel pump can leak fuel into the crankcase if diaphragm is ruptured, might check that.

I have the same motor except a 30 hp.
Maybe you have a leaky primer?
My manual primer was stuck open once and it smoked quite a bit.
Check your primer and make sure its shutting off the fuel.
Good luck.

Ahh didn't even think about the primer sticking. I assume you disconnected the discharge line for it and checked to see if fuel continues to flow?

Well seeing as I purchased this motor used and have no idea of the service history, I decided to do a full and complete tune up. I just ordered a new water pump kit, thermostat kit, fuel pump kit, new (and pricy) fuel primer pump, plugs and wires as well as I plan on cleaning the carb. Hopefully this helps with the smoking issue. Once I thought about it the motor would only smoke after a few minutes of running, after that it was every time the motor would start it would smoke. Although I am not an advocate of just throwing parts at things, I often run long distances so piece of mind knowing all is well is worth a few extra bucks...

Could be just the nature of the beast, I've got one 25 that smokes like that and one not as much. Both run well , same tank same fuel mix. But I agree Bowhunter, peace of mind is worth a few bucks.

I have a strong feeling that my smoking problem is coming from the primer pump. I disconnected the fuel line that goes from the primer pump to the intake manifold and although I did not see fuel continue to come out after I primed it, the O-rings on the inside of the pump are squeaking really bad. I sort of believe that they have become dry rotted and hard thus not sealing properly, and when the primer pump is under a vacuum while the engine is running it is drawing fuel from the bottom of the float bowl through the failed I rings. We will see when I get the new pump how it reacts.

I am hoping I figured out why my motor was smoking so bad. Apparently the guy I bought it from was full of poopy. He claimed the water pump was replaced but to me it looks factory... If he or the previous owner replaced the pump, they installed the pump backwards per the manual. Manual states to mount it in a counter clockwise manor. The old was installed clockwise. Also, the impeller was nearly melted to the cup. The bottom where water enters was almost completely covered in melted plastic. I believe my motor was running hot but not to the point it would burn itself up. Thank The Lord above!

Bowhunter1661 said:

... If he or the previous owner replaced the pump, they installed the pump backwards per the manual. Manual states to mount it in a counter clockwise manor. The old was installed clockwise.

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You can fix an impeller, ya can't fix stupid.

it looks like it was ran without any water.

I couldn't agree more that is was run outside of water. The PO of the motor must not have had a clue of what he was doing. Everything I touch seems to be out of spec. Linkages were all screwed up and out of adjustment. I feel he tried to make the motor run well but could never figure it out. It ran like a champ in a water tank though. Thank fully It looks like she is finally getting lined up.

When I bought it he ran the motor in a test tank for me. When he did this he reved the engine in gear and all seemed well (I believe due to the fact it wasn't under a real load). However when I got it home I notice right away how far off everything was. The butterfly was not even opening at WOT. He had the roller adjusted so it would ride on the cam during the entire throttle travel.

Thankfully I know somewhat of what I am doing on the motor. If I was an everage how looking for a motor ready to go I would have been screwed. In the ad he described the motor as "excellent running, excellent shape. Now I can say with confidence the motor is back to factory quality.

I find something interesting in your last post.
I have a "04" Johnson 9.9 that I followed the instructions from the manual for "link and sync." It would not idle when the throttle was turned all the way back to idle, it would stall. Also when I let off slightly on the throttle a WOT, it would run better. I tried to set it up as per instructions and no change. The roller was on the mark and everything was adjusted as per instructions; several times!
Decided WTH, and started playing with the linkage and got it to idle and run perfect. The linkage is now adjusted different than spec., and that's where it seems to work! ???????????
I have it on a 1654 FB Tracker GRIZZLEY, so when I'm running it it's definitely pushing a load.

When I ran the motor yesterday mine did the same exact thing. When at idle it would die. I luckily have an RPM gauge attached to the motor. With the adjustments made in the photos the motor would run approximately 400 rpm's at idle far below factory spec. My motor needed to run around 8 to 900 RPMs in order to get 600 RPMs in forward gear. In order to prevent the motor from dying I had to adjust the idle speed knob on the tiller handle. Also I set the idle adjustment needle at approximately 1 1/4 turns out from lightly seated. Once I made those adjustments the motor idled at about 900 RPM and in forward gear would run approximately 675 rpm's.

Just an update, the motor runs fantastic now. No smoke from over heating, pisses water like a fire hose. Runs like a dream, fires on first pull! Couldn't be happier with this motor so far. Although I do think I am going to to the 35 carb and intake swap..

Also, I installed a jack plate on the boat. The anti vent plate sits about an inch above the bottom of the boat now. Still has great acceleration, however, it does slightly ventilate when getting up on plane. I can throttle right through the ventilation though. Since I raised the motor it now has an insane amount of tq steer. The boat pulls really hard right. I do not have an adjustable trim tab. I did tighten the resistance screw though. I'll see if that helps, if not I may buy a tq tab.

I believe the motor can stand to go up another 1/2". The anti vent plate still slightly sits in the water with the 4.5" of setback the jack plate gives. Top speed is at 30 mph on the dot.