Spitting oil from prop! See pic.

[toddingalls]

My 1990 Yamaha 115 hp 2 stroke is spitting oil from the prop exaust, quite a bit... see attached photo.
Smells like gas/oil mix which makes me think I am just running too rich, but I have oil injection.
Tried running premix oil/gas for about 10 minutes with same result.
Am I just burning off excess oil? Or is there another problem?
Runs rough, backfires. Plugs are also oily. Changed plugs a coule times already, cleaned carbs.
Any ideas?
Any help would be much appreciated.

 

[robert graham]

Re: Spitting oil from prop! See pic.

Looks pretty darn rich!..maybe a bad fuel pump diaphragm sucking raw gas into cylinder...maybe stuck or faulty carb float causing very rich mixture on that cylinder. Maybe you can put in clean/dry plugs, run the motor, remove/inspect plugs to determine which cylinder is running rich. Good luck and let us know what you find!

 

[toddingalls]

Re: Spitting oil from prop! See pic.

Ran new plugs, all 4 plugs came out oily. Carb floats seem okay. But I noticed carb floats don't rest parallel with the carb housing. They are kind of angled upwards. Do I need to bend these down so that they are parrallel at resting position? Seems strange for all 4 to be angled up like that.

Also, when I ran the premix oil/gas I just took the control arm off of the oil pump to disable it... would that method actually disable the oil pump for proper testing? I am thinking it could be a bad oil pump still.

What are your thoughts?

 

[robert graham]

Re: Spitting oil from prop! See pic.

I wouldn't adjust the carbs/floats, as they are probably O.K. When you pump the primer bulb does it get hard? If so, then your float valves are working good and shutting off the fuel when floats rise. Maybe your oil pump is pumping at max all the time? Good Luck!

 

[toddingalls]

Re: Spitting oil from prop! See pic.

Robert, thanks for your replies!
Primer bulb is not getting hard. Should I adjust floats? I looked for leaks in the fuel lines and replaced the bulb too.

 

[toddingalls]

Re: Spitting oil from prop! See pic.

Update: adjusted the oil injection to a lower setting, seemed to run a little better, but still running VERY rich. Oily plugs and still a lot of unburned oil and gas coming from prop exaust.
Checked fuel pump diaphram.. no visible holes/tears.
Also, primer bulb gets firm when pointing arrow up now.
Any ideas anyone how to fix the unburnt oil gas problem?

 

[toddingalls]

Re: Spitting oil from prop! See pic.

Still having problem with HEAVY unburnt oil and gas coming from prop exaust... any help from members?
This what I done so far:
-Cleaned carbs
-Changed plugs x 2
-Disconnected and capped oil injection line to test with premix
-Checked fuel pump diaphram for rips and holes
-Replaced primer bulb
-Checked floats and float needles

 

[toddingalls]

Re: Spitting oil from prop! See pic.

Okay, got my oily exhaust problem fixed... re-cleaned carb jets and adjusted fuel/air mix... and that did it!
Now I have another problem... runs and idles okay in drive-way, but won't idle good at launch ramp. Maybe being on the slope of the ramp is effecting my gas lines somehow?
Primer bulb doesn't really stay firm in either location.
Any ideas?

 

[Borgey401]

Re: Spitting oil from prop! See pic.

Pretty sure that when a boat will run on muffs but not in the water it's usually an electrical issue (humidity changes when going from land to on water). Either that or the back pressure on the exaust from the water.

 

[brentjsimm]

Re: Spitting oil from prop! See pic.

i may be completely off base here, but don't outboards typically "run rich" when on muffs? i've read that you will get SOME unburned fuel when on the muffs. maybe you had too much, i don't know. where i'm going with this is if you adjusted your fuel/air mixture while on muffs to run at good idle, you would be running lean when the boat is actually in the water, and the pressure against the exhaust is higher. that may be causing the stall-out, or cause it to not idle. what do you think? maybe you should adjust your air/fuel mixtured while in a tank, or in water, and not while the muffs are on. make sense?

 

[shallowmindedguy]

Re: Spitting oil from prop! See pic.

When you take oil control linkage off oil pump is in wide open or max oil position so you should have seen lots of smoke.

My guess is that it is a leaking fuel pump. (fuel is leaking into block from the back side of the fuel pump) Just loosen the 2 bolts that hold pump to block and squeeze the primer bulb to see if you have any leaking fuel. If you take pump off do you see any fuel in back of pump? In an engine of that age I would probably think it is time to change the diaphrams as a maintenance item anyway.