Fuel in Oil??? rich condition or no?

[Spare_Time]

1987 stingray w/ Mercruise 165 4cyl. (similar to merc 470). 2bbl mercarb and alpha one outdrive.

I rebuilt the carb and started getting her tuned up and for the life of me it seems as if I can't get it to run. Its running way too rich so I pulled the carb checked the float measurements again etc... and still rich. I noticed as im running the engine I can smell an unusually strong gasoline vapor around the flame arrestor as if someone was pumping gasline fumes into my nose....

I continued to tinker around with the idle and mixture adjustemnt to no end leaning the carb out to almost seating the mixture screw...mind you i've also had two gaskets (valve cover and lifter cover gaskets) leaking like sieves. Never thought much about anything it until I pulled the breather tube off the valve cover while the engine was running. All the sudden the engine perked right up and ran nicely. The air coming out of the breather tube made my eyes water and STANK like gasonline vapor... now im no marine mechanic but even on an automobile the breather tube if anything should smell like OIL not gasoline.

Does this sounds like a fuel in the oil condition? Why else would the carb be runnig SO rich that I can't lean it out enough. Could this be the cause of my leaky gaskets that I can't seal? If the gas is thinning out the oil wouldn't it allow it to pass through the gasket? Its all starting to make sense and point to a shoddy fuel pump (in my opinion).

Thoughts, opinions, etc... I want to get my boat back in the water!!!! In stead of spending my "spare time" on the boat, im spending my spare time fixing this stinking thing. Summer is at its peak and i don't want to miss a day!!!!!! arrrrrrrrg

Thanks SO Much and happy boating to those who's boats work!
Al Conforti

 

[Robj]

Re: Fuel in Oil??? rich condition or no?

I am unfamiliar with your particular engine but a common cause of gas smell in the oil is a ruptured diaphram in the fuel pump. Assuming yours has a mechanical marine fuel pump, check the clear line going from the spark arrestor to the fuel pump. If there is fuel in the line, the fuel pump needs replacement. Also change the oil ASAP.

If there is no clear line, then you have a automotive pump that should be replaced with a marine one.

Good luck and have a great day,

Rob

 

[Maclin]

Re: Fuel in Oil??? rich condition or no?

What does the oil from the dipstick smell like? If it is obvious by the smell that it is contaminated with gasoline then you must change it and the oil filter out now then IMMEDIATELY FIX WHATEVER IS ALLOWING GASOLINE TO ENTER THE CRANKCASE. Then run it until warm and change the oil and filter again to be sure.

Some possible causes:
The fuel pump can be ruptured inside and be forcing gasoline into the crankcase. The carb could be overflowing and allowing raw gasoilne to run into the intake and on into the cylinders and leaking past the rings into the crankcase. Some carbs have some well plugs in the bottom of the fuel bowl that are epoxied in, it seems that the newer gasoline formations are dissolving the older epoxies and the gasoline can leak directly into the intake manifold until the fuel bowl is dry.

What to look for:
The fuel pump may have a small clear (or used to be clear and now yellow) hose running to the carb or the flame arrestor. If it has fuel in it then that is your sign that the fuel pump is failing internally.

If the carb fuel bowl drains by itself then that is your sign that the carb needs rebuilt and those plugs attended to with newer epoxies (if your carb has these, not all do).

 

[Maclin]

Re: Fuel in Oil??? rich condition or no?

Sorry, did not mean to double up on the advice, Robj's post was not there when I started mine....good stuff though.

 

[chiefalen]

Re: Fuel in Oil??? rich condition or no?

Does the float have pin holes in it? Maybe it's full of gas and not air.

Maybe the float is catching on something.

You could try tapping the carb to dislodge the float.

Others have already told you it could be the fuel pump you could pressure test it.

No matter what if the oil has fuel in it you have to change it out. Oil filter also.

 

[Spare_Time]

Re: Fuel in Oil??? rich condition or no?

Thanks Folks,
I suspected the fuel pump and pulled it. The clear overflow hose i guess you would call it was pumping quite a bit of gas. I assumed I was repacing the pump anyway so I took this one apart. The diaphgram is SHOT! THe oil is drenched with gasoline. Guess im throwing another $120 at this boat. AYE AYE AYE!

On a side note, once I change the oil and replace the pump, do I have to replace the cork gaskets again? or do you think they will be ok? I JUST replaced them and the gas/oil mix was leaking past them. Im hoping the clean oil will be thick enough to not leak past them.


THanks Again!

 

[chiefalen]

Re: Fuel in Oil??? rich condition or no?

New gasket please. Should come with the pump, if not 2 bucks.

 

[Maclin]

Re: Fuel in Oil??? rich condition or no?

I think you mean the valve cover and lifter cover plate gaskets. Up to you if you want to run it first to see if they leak less.

I do not know why they would leak at all even with the thinner oil mixture so they may need to be replaced again anyway. Be sure to scrape off all the old gasket, not just your last one but any previous ones that may be so dark as to blend into the block or head.