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Gas in oil 50 merc 2bbl

T

tombo23

New member
can someone tell me possible r

can someone tell me possible reason for fuel in my oil
Found a lot of gas in oil
had hard time starting after unwrap so quite a bit of starting cycling (sensor was gone but since replaced)
also noticed when i was trying to start engine after returning key from start to run(engine didnt start) the fuel pump would keep running for few seconds is this normal shouldn't the pump stop at that point i know oil switch powers pump while running and starter controls it while starting could i have a faulty oil switch that keeps pump on and dumps fuel into intake could it be a faulty starting circuit doing this?
i know i am talking to much but i need help bad !
 
""Found a lot of gas in oi

""Found a lot of gas in oil, had hard time starting after unwrap so quite a bit of starting cycling (sensor was gone but since replaced)"

How much fluid was on the dip stick above the full mark? Get the oil and filter changed and clean the flame/spark arrestor before starting it. Hard time starting may have dumped the gas in the oil. Change the spark plugs and see if she'll start. If not then check for spark."
 
sorry the engine is running fi

sorry the engine is running fine i am trying to find out possible causes of gas in oil could it be the pump is dumping fuel while key is in run mode could the oil switch be getting stuck and keeping fuel pump on when engine is not running ?
 
thomas long
In all probabili

thomas long
In all probability the diaphragm in the fuel pump is shot and fuel is getting to the other side. Your tube from the pump to the carb should show fuel if this is the case.
Bert
 
Bert:

I have never dismantl

Bert:

I have never dismantled an electric fuel pump. Is it diaphragm operated like a mechanical pump?
 
Guy Gaspar
Sorry I thought

Guy Gaspar
Sorry I thought it was a mechanical pump. If it's not the pump it must be getting in through the carb and intake. I had a carb once that had a blown diaphragm on the power valve and it just puked gas into the engine.
Bert
 
is it normal for the fuel pump

is it normal for the fuel pump to run for few seconds when key is returned to ignition position even though the engine is not running
thats why i think i might have faulty oil switch
 
"Thomas:

There will still b

"Thomas:

There will still be oil pressure when you shut off the key but only for a moment. Since you said it is running good, the switch may be the problem but I would also suspect a faulty pump relay; contact points on the relay can stick intermittently if they are burned and/or pitted. Replace the switch if that's what you think is the problem."
 
"guy there is no pump relay pu

"guy there is no pump relay pump gets voltage directly from starter when ignition is in start position and from oil pressure switch when running. anyway my big concern is how i got all this gas (about two quarts) in my oil pan. can it be from trying to start it(when i was having trouble starting it)so many times, or could it be need valve or float prob in carb"
 
"Your pump should shut off if

"Your pump should shut off if the required pressure at the outlet is met. It cycles on and off to maintain this pressure.

That fact that it keeps running indicates that your needle and seat at the carb is not controlling the level in the carb. The carb is likely flooding and dumping gas into the intake, which runs down the cyinder walls into the oil. Gas can run down cylinder walls easily, since it is very thin and non-viscous. This is bad as it is washing away the vital lubricating oil on the cylinder walls.

You need to fix the carb float problem first, and I would pull the plugs and squirt oil into each cylinder before trying a restart.

Rod"
 
I have to agree w/Rod. A mini

I have to agree w/Rod. A minimum would be to change both the float and needle/seat.
 
are you saying that if the pum

are you saying that if the pump gets backpressure from carb then it wil cyle off so if the float or needle is screwed the pump will just continue dump fuel into carb/intake? secondly i was told that there is no way i could get that much (two quarts) gas in oil from just trying to start over and over aprox 40 times.( i know this is dumb)
 
btw the engine runs fine no sp

btw the engine runs fine no sputering or such if i have a float/needle problem wouldn't that affect idling?
 
"Thomas;
Correct; if the need

"Thomas;
Correct; if the needle and seat are leaking, the carb will overfill and flood. The gas has no where to go but down the throttles into the intake.
If this were the case though, it would not want to run at all. You say its running fine, so the carb must be OK. I am at a loss as to where the gas is coming from.

Rod"
 
"Thomas:

Let's start ba

"Thomas:

Let's start back at the beginning. Did the engine ever start? You state there are 2 qts. of gas in the oil. It does seem odd that it has that much gas in it. Who did the last oil change? Maybe it was over filled? Is the oil a little milky? Maybe 2 qts. of water are in the oil with some residual fuel?

Pump or drain the oil and catch the first 2 qts. to see what it actually is. If it doesn't look like water or milky, let a pint sit overnight in a quart jar to see what settles out.

If water comes out of the oil pan, pull the plugs and add 1 tbs. of engine oil to each cylinder, ground the coil, hook up a set of muffs w/water and crank the engine 10-20 seconds. Check the oil pan for more water and pull the plugs and see if there is water in the cylinders. Block, manifold or riser may be cracked.

If all is well, try to start it w/fresh oil and clean plugs."
 
"ok guy here you go
when ifir

"ok guy here you go
when ifirst uncovered boat this spring had prob starting it would start intermittently and run bad and die i cranked the engine a lot would hear fuel pump run for few seconds even though engine wouldnt start and while key was returned to and in ignition position i since fixed problem (dist sensor) and engine runs perfect. when i went to change oil noticed oil was grey in color and pumped out approx 2 gals. smelled oil and is was gassy. but the kicker here is the fuel pump running on i have never heard that before when i have ever had prob starting in past i realy think thats how all that fuel got dumped in pan only things that confuse me is 1. why did the pump keep running because with key in run position pump is only energized when there is oil pressure which is impossible with no start and 2. if the fuel pump kicks off with back pressure from needle/float valve, like rod states, bowl should have been full, causing back pressure and stopping pump. my initial feeling was the oil switch but that doesnt' make sense given the pump would only run for few secs"
 
I believe since it is running

I believe since it is running fine now that the problem was a stuck float valve from storage over the winter - gummed fuel - and that the starting attempts indeed pumped a flood of fuel into the cylinders. By the way I lost engine on an expensive riding lawn mower when the float valve stuck open out in field and the excess fuel in oil killed the engine bearings before it was obvious something was amiss.

I would definitely put some cleaner in the tank now and again the last tank running next fall. Every spring I always add a can of carb/injector cleaner to the first tank also - just in case.

Glad you got it to behave before major damage done.
 
"Thomas;
Have you always been

"Thomas;
Have you always been able to hear the fuel pump running at times?
It would be easy to check the oil pressure switch with a voltmeter to see if its shot or not.

I agree with you that the fuel pump should only run when you have the engine running and there is oil pressure, or when bypassed in start mode. Of course you should not hear it running in either case anyway.

I installed a pushbutton bypass on my previous 4.3 for just that reason. It was terrible on a cold start after sitting idle for a few days. It took forever for the fuel pump to refill the carb, while you were sitting there with the starter grinding. I used to worry that the battery would be dead before it would finally start. My bypass allowed you to prefill the carb before starting, and completely eliminated the problem. When I held the button down I could hear the pump run, usually only for a few seconds. Then it would quit when the carb bowl was full, and the engine would start immediately.

Rod"
 
"I just want to thank you guys

"I just want to thank you guys and guy
for all your help, this forum is an invaluable resource to us backyard mechanics who do not have the money(or understanding wife) to squander on professional mechanics(who usually rush and goof up the job anyway)"
 
"Thomas-Long:

It's our

"Thomas-Long:

It's our pleasure to help. One thing that still bothers me: "when i went to change oil noticed oil was grey in color and pumped out approx 2 gals. smelled oil and is was gassy". Did you mean gray as in creamy or milky? I'd keep my eye on the oil for water intrusion.
rain.gif


Went to Brookville Reservior Friday. The water level was up nearly 7' from 3 days of rain. Ramp was nearly level w/the road and the docks were 50'+ from the bank. Launched her and fished catching a mixed bag. Speedometer quit! Tons of debris in the water from the runoff. It was worth every minute.
proud.gif
"
 
i think you may be right but w

i think you may be right but what do you mean by creamy or milky grey oil has solid color no streaks kind of creamy also if it it is water intrusion how do i tell where its comming from ? ie manifolds or cracked block?
 
"Thomas:

My statement may b

"Thomas:

My statement may be just an interpretation of words. Engine oil should be semitransparent w/the dregree of transparency dependent upon the level of dirt and blowby contaminents. To me, gray color means moisture in the oil. To others it just means dirt oil. Sorry if I created an unnecessary scare.

Water in the plugs usually means upper engine issue. Exhaust mans. and risers may be cracked whereby water runs into open exh. valves and then trickles by pistons to crankcase.

Water in oil only is usually a block issue."
 
"i just ran thru third oil/fi

"i just ran thru third oil/filter change first change oil came up grey again. Second change oil in stick looked clear completely, after running engine with muffs for good 20 mins(btw someone once told me i shouldn't do that ?) no prob with oil press or temp and running real smooth noticed greyish tint at filter but not as bad as b4. Now on third oil/filter. is there anyway to know for sure if i have probs b4 i put in water?"
 
Dump what's in the filter

Dump what's in the filter and let it sit overnight in a jar to see what settles out. You should be just fine if no water drops to the bottom. Does your engine reach operating temp? If not that could produce water as a combustion byproduct in the oil in small amounts.
 
"everthink lookds normal now t

"everthink lookds normal now temp goes up and stays at level 170 oil pressure 40 all mid range on meter i think it was a gas dump though still have fuel pump running for few secs on when return to ignition position i tried it with high tension lead removed from dist i am pretty sure that was cayse of excess fuel cab you confirm what rod told me way back that the fuel pump should not run when back pressure from carb is received? i just dont understand it though, if that was the case and float/needle was stuck it would be gulping to much while running and conk out but its purring like a kitten while running"
 
"thomas;
There is no problem

"thomas;
There is no problem running on the muffs as long as you have plenty of water flow and the temps stay OK.

Grey in your oil is not good.
That almost for sure means water is getting into the oil.
You could have a leaky head gasket, cracked head or block, or who knows?

The only way to know for sure it to pressure test the block cooling system by isolating it at the T'stat housing and pressuring up to 10 psig or so. Then see if it holds. If not, you have a leak somewhere.

You could try pulling the plugs and see if you have water in any cylinders. If so, this would suggest leaky head gasket, cracked head, or cracked exhaust manifold.

Rod"
 
how come everything is clear n

how come everything is clear now? ran engine for two 1/2 hr stints are you telling me for sure its not gas like i though that pump was running while engine wasen't spinning is it at all possible it pushed passed needle and dumped into manifold im going to dump grey oil in old big pickle jar if its water should seperate like guy says right?
 
well think i just rpoved it wa

well think i just rpoved it was gas took a little of that grey oil (after filling one gallon pickle jar)and put it in a saucer put a torch on it it wound up igniting gas molecules(saw crackling sparks and flames with smoke trail till all burned off) and was left with black crude
 
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