Unburnt fuel/oil mix out the wazoo! Pics included!

[littletunny]

1991 Evinrude 48 Special.

I have noticed a lot of unburnt fuel mixture (sludge) running out of the exhaust after a day of boating. I am also experiencing wet plugs though the motor runs fine.

I am assuming the wet plugs have a connection to the unburnt fuel/oil mix.

According to Clymers manual, wet plugs or wet fouling is caused by:

1. Spark plug heat range too cold
2. prolonged trolling
3. low speed carburetor adjustment too rich
4. improper fuel oil ratio
5. induction manifold bleed off passages obstructed
6. worn or defective breaker points

So I am thinking its either 5 or 3.

How could I check the bleed off passages?

I have done the low speed carb adjustment per the manual.

Thoughts?

 

[psteurer]

Re: Unburnt fuel/oil mix out the wazoo! Pics included!

I think what Clymers means by "induction manifold passages obstructed" are the recirculation valves. These are at the top and bottom of the manifold and connected by a hose. They serve the purpose of recirculating unburned fuel back into the combustion path. Is the hose connected? Your second pictures shows a black oil coming down from the engine block so it could be this.

Also, make sure that the stuff coming out is unburned fuel and not lower unit oil. You can smell it and tell or you can pull the lower unit drain plugs and see what it looks like. Unburned fuel is a normal thing with 2 strokes. If you do a lot of idling you have a lot more.

 

[mikesea]

Re: Unburnt fuel/oil mix out the wazoo! Pics included!

I would bet its one of 2 things,your primer is either in the on position,or its leaking thru,OR ,your fuelpump is going bad,allowing fuel to enter the engine thru the port that operates the diaphram ,which makes it work,over fueling is a result of any of the above,you can disconnect the hose that picks up the vaccuum for the pump,while squeezing the hose ball,note if fuel passes out that vac.line,it shouldent,as for the primer,disconnect the smaller lines to the carb,while running see if fuel passes ,it,should not if the red lever lies peredicular wiyh the primer body,be sure eng is already been running to ease starting for test

 

[CaptainHook]

Re: Unburnt fuel/oil mix out the wazoo! Pics included!

My brother's 1996 Evinrude 112 spl was doing the same thing. A carburetor rebuild and fuel pump replacement solved the problem.

 

[ezeke]

Re: Unburnt fuel/oil mix out the wazoo! Pics included!

What you have on your skeg is not unusual after a day of boating, especially if you troll a lot. But, in addition to the things already mentioned, you may be able to improve it by making sure that your thermostat is functioning properly. Synthetic TC-W3 oil should help as well.

BTW, If your gear oil looks like that, it's worn out.

 

[littletunny]

Re: Unburnt fuel/oil mix out the wazoo! Pics included!

Hey Guys,

Thanks for all the advice.

I no its not foot oil because I can see it leaking from the exhaust when I pull the prop. I just replaced the fuel pump so that shouldnt be it.

Mikesea you may be on to something. I will check this afternoon and report back. How does the primer solenoid work exactly?

 

[mikesea]

Re: Unburnt fuel/oil mix out the wazoo! Pics included!

are you absolutly sure there is raw gas in that black gunk,it is common for residue to settle out after running ,the black is carbon.As for the primer,the larger port is the fuel feed from the line that also feeds carbs.There is an electric plunger ,that when you activate your choke function will give a squirt of raw gas into the intake manifold ,sometimes you get an electrical problem and cant get the choke to operate via the elec.so,they have a bypass,if you turn the red handle 90 degrees and squeeze your ball ,you get same effect manually,once started ,you need to turn red handle back,or it will flood,sometimes it gets a bit cocked and will pass a bit or more,but,there is also a rubber diaprham in the unit that can go badmor orings that can pass,with the new ethonol gas,the older rubber pieces are getting hell from the alchol and breaking down.Fuel hoses,fuelpumps etc.Even some gas tanks.Let us know how you do.There are rebuild kits for that primer.You might also take it apart,easy,just four screws,then check the orings on the lever.If it was passing bad,you would have trouble mostly at idle

 

[psteurer]

Re: Unburnt fuel/oil mix out the wazoo! Pics included!

It is a very common thing for an unsuspecting owner to turn the red handle on the primer in order to compensate for a engine that will not run due to a clog in the idle circuit of the carburetor. The primer is then serving as a bypass for the carburetor idle circuit. But it sure will result in a large amount of unburned fuel that would come out the exhaust and/or the lower unit relief holes.