2003 Mercury 115 fuel on water after shutting off motor

[finish line 88]

Looks like there is fuel out the exhaust after running and shutting off the motor. Does not do it all the time. Just rebuilt the fuel pump thinking maybe that was the problem. Any help as to what to check would be great. Thanks

 

[alldodge]

Looks like there is fuel out the exhaust after running and shutting off the motor. Does not do it all the time. Just rebuilt the fuel pump thinking maybe that was the problem. Any help as to what to check would be great. Thanks

Might be running way to rich. What do the plugs look like?

 

[Faztbullet]

2 or 4 stroke???

 

[finish line 88]

Plugs look good. It is a 2 stroke

 

[Texasmark]

Maybe you just don't see it all the time due to circumstances at the time. Since you kill the engine by killing the ignition, until the engine quits rotating, it's processing fuel. If you kill the engine with the throttle open more than idle obviously there could be more residue. Or if boat or current movements are different observation would be different.

Another point is that the fuel and oil are petroleum products which are lighter than water and thus float. With no restrictions the fuel will spread out to the single molecule level which means that just a single drop of fuel could spread out to a 20-30' circle if allowed in dormant water. I know this because this is how the size of the oil molecule was determined....a drop of oil was applied to a standing pool of water and the size of the ring it made was analyzed and the answer was produced.....oil molecules are tiny!

Mark

 

[finish line 88]

Thanks for the reply. I am on a lagoon that is not thru flowing so the water is very still. It does not show up all the time so Its hard to figure out. It is a 2 cycle carb motor and i do get some drainage from the carbs when the motor is tilted up. I guess it is just the nature of the beast.

 

[Texasmark]

do get some drainage from the carbs when the motor is tilted up. I guess it is just the nature of the beast.

Within their limits considering how far you tilt up, if the needle valve in the carb is doing it's job, you shouldn't have any leakage out the venturi. Possibly the leakage you see on the water is fuel that leaked out of the venturi and found it's way out of the cowling and into the water. If you have a conventional installation with the transom notch a reasonable distance from the water and tilt the engine such that the lower unit is just out of the water you shouldn't have any leakage. If so, new needle valve and reset your float level ensuring that there is no binding and the float works freely, aka carb kit.

Mark

 

[finish line 88]

I found that the vent cap and check valve on the oil reserve tank is missing. Looks like some oil has come out of the vent hole. I ordered the parts so I will see if this is some of the problem. Oil on the water I think would look the same as fuel.

 

[Texasmark]

I found that the vent cap and check valve on the oil reserve tank is missing. Looks like some oil has come out of the vent hole. I ordered the parts so I will see if this is some of the problem. Oil on the water I think would look the same as fuel.

What vent cap and check valve? I had the '02 90 and I only recall seeing the fill cap that protruded through a hole in the cowling (so you could top off your oil without removing the cowl) on top of the reservoir. It did have a gasket and if it failed and you tilted your engine up high enough with the tank full it would leak into the engine compartment (making a puddle) and from there to the water, eventually.

On your comment about gas and oil looking the same, yes, they both come from oil and as I said before, unrestrained petroleum will spread out until it's one molecule thick.

Mark

 

[finish line 88]

The vent is on the top rear of the oil reserve tank. The P/N is 19299A 1 - Vent Assembly. It is a little check valve and a cap that goes on the tank.

 

[Texasmark]

Well I guess they changed things after 2002. I didn't have one and my manual which covered 75 thru 125 inline engines of earlier years didn't elude to it either. I was aware the larger engines had an onboard reserve like my son's 150.

Learn something every day.

Mark

 

[PISTONESAL]

I have the same vent assembly on mine that is missing and I also notice some oil in water. Did this resolve the issue? How does that assembly get installed? Please advise thanks

 

[GA_Boater]

I have the same vent assembly on mine that is missing and I also notice some oil in water. Did this resolve the issue? How does that assembly get installed? Please advise thanks

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