1988 88 hp johnson smokes excessively

[crabbydad]

hi,
i am looking at a 1988 88 hp johnson. the compression is 125 on all 4 cyl., but it smokes a lot. i read it may just need to be decarbed. are there any major problems that could cause this?
thanks.

 

[emdsapmgr]

Re: 1988 88 hp johnson smokes excessively

Great compression! That engine does not have an oil/fuel mixing pump. Just a stock premix type fuel pump. If the oil is being premixed at 50 to 1, then there must be another reason for the smoking. Possible the engine is running cold. If one (or both) of the stats is stuck open, the engine can run cold and smoke somewhat more. Check the powerhead temps with a laser temp gun when it's warmed up. Should be at least 143 degrees at idle. If the carbs leak any fuel out the front of the carbs, the excess fuel will get recirculated into the bottom cyl through the airbox drain hose-that can cause excesssive smoking till that extra fuel is burned off. Is there any smoke inside the cowling when running?

 

[crabbydad]

Re: 1988 88 hp johnson smokes excessively

i went ahead and purchased the motor and removed it from the boat. i took a chance assuming there was nothing major wrong with the motor. i paid $600 for the motor and control. the guy had just purchased the boat to restore, so the fuel in the tank was from the previous owner-status unknown. hopefully i will get it on my boat in the next week or 2. i dont think there was any smoke inside the cowling, i had it off. i smoked more right at startup, then not as much. the motor may not have been warmed up. when i get it on the boat i will check the temp. the motor did seem to be idling a little high. thanks for the help, i will report back when i get it running

 

[toddschubert]

Re: 1988 88 hp johnson smokes excessively

I recently bought the same motor on a Larson hull. I was told the main tank was empty and was running on reserve. I dumped the amt of oil in main tank necesarry for 50:1 but had cranked her up for a while thinking I was on reserve tank. Long story short, the lines were crossed and I was in fact running on main tank with nothing but oil hardly. Smoked like all get out but ran!!! Your guy may have had a build up of oil over years and in fact had more than 50:1 . Btw, I'm only getting 60 PS I out of all 4 aprox and water in number 4 and it purs like a kitten. I don't get it.

 

[boobie]

Re: 1988 88 hp johnson smokes excessively

Crabby, put fresh fuel in it mixed 50:1 when you get ready to run it and take it out and run the hell out of it and see if the smoking stops.

 

[crabbydad]

Re: 1988 88 hp johnson smokes excessively

thats what i figured. after closer inspection in my garage, i could very faintly smell old gas at the carbs, also the screw that holds the shift rod from the lower unit is broken. if i need to remove the carbs and clean them, i will fix that also. it looks like only the head is broken off, so i wont worry about getting it out know, unless i have time.

 

[crabbydad]

Re: 1988 88 hp johnson smokes excessively

put the motor on the boat last weekend. fired it up with fresh gas and it smokes normally. i'm anxious to get in the water and see how it runs