Two stroke oil leaking into fuel hose, 30hp 1993

[MrOtto]

1993 30hp two stroke Mariner serial no. 689 S 251061

Engine was tilted for two weeks. Upon start up, in ran for 3 seconds and then would not run. It would only run on starting spray fluid after that. I pushed the ball valves in the engine tank and motor connection to the fuel hose to check flow, and oily blue fuel came out. I also drained the carb and it also looked bluish.
Engine started fine after fuel line/carb was drained and fuel hose was pulling fuel from a can I use for the lawnmower.
I suspected someone had pored two stroke in the fuel tank, but when I drained the tank the fuel looked and felt ok in color and "slipperiness"
So, could two stroke oil be leaking from the oil tank into the fuel lines of the motor? Flooding the carb and fuel lines with two stroke oil.

 

[Texasmark]

1993 30hp two stroke Mariner serial no. 689 S 251061

Engine was tilted for two weeks. Upon start up, in ran for 3 seconds and then would not run. It would only run on starting spray fluid after that. I pushed the ball valves in the engine tank and motor connection to the fuel hose to check flow, and oily blue fuel came out. I also drained the carb and it also looked bluish.
Engine started fine after fuel line/carb was drained and fuel hose was pulling fuel from a can I use for the lawnmower.
I suspected someone had pored two stroke in the fuel tank, but when I drained the tank the fuel looked and felt ok in color and "slipperiness"
So, could two stroke oil be leaking from the oil tank into the fuel lines of the motor? Flooding the carb and fuel lines with two stroke oil.

TCW-3 (Two Cycle Watercraft-3rd iteration) oil is deliberately dyed blue so that you can tell in a glance that you have added your oil on both pre-mix and oil injection engines. Lawnmower/small engine non marine oil isn't the same formula as marine oil is made for constant full throttle operation, and the other is for high heat air cooled engines running 3500 governed RPM...Published data from mfgrs..

Not familiar with your engine as to whether or not it is VRO internally stored oil with a pump or you have to use premix. On VRO I never took a pump apart but I don't think that they leak, having had both a 90 and 115 VRO.

If they did, then engines with an oil tank under the cowl would slowly dribble oil down into the fuel line, filling the line over time, so that when you tried to start the engine all it would get would be oil....until it processed all the raw oil and started picking up some fuel mixed in from the tank. But by that time the plugs are probably oil fouled and the engine wouldn't start.

In your instance possibly the mixture in the bowl had mostly oil with fuel evaporating due to lower vapor pressure, and the bowl was left with mostly oil. Otherwise I can't help you.

 

[dingbat]

My carbs are full of oil every Spring.

I don’t drain my carbs so the fuel evaporates leaving nothing but oil in the bowls.

 

[Faztbullet]

Disconnect Autoblend unit in boat and premix fuel.

 

[MrOtto]

Disconnecting oil injection is not an option as long as it works. It will be hopeless to teach the 10+ different users of the boat to start adding two stroke oil to the fuel tank, the risk of it running without oil is too big.

Engine starts fine after a couple of days tilted, but I can't believe it not starting and excess of oil in the fuel hose was an isolated incident.

Anyone seen the repair manual for this engine? I have only the original user documentation.

 

[airshot]

Disconnect your fuel line from the engine when your done for the day. As the gas evaporates it leaves oil, with the fuel line connected, what ever oil is in the line can bleed over time further into the hose to look like premix. I always disconnect my fuel line at the dock and let it run for a minute to use up the gas in the carbs. With the engine running and no new fuel coming in, it adds a slight amount of extra oil so there will be oil for the next startup.

 

[MrOtto]

I was thinking about disconnecting the fuel line when the outboard won't be used for, let say a week or more, (two-three days tilted it starts fine, smokey though first 10 seconds), then I guess the check valve will be in use, with hose disconnected to the outboard, and neither oil or fuel can run back into the tank. With the hose installed there are no check valves in use and fuel and oil can run back into the hose and fuel tank.
Could E10 fuel have damaged something? E10 might have been used last year, no Ethanol blended fuel is used this year.
Anyone seen a maintenance manual so I can identify the components?

 

[MrOtto]

This looks the right parts for the serial number:

https://www.marineengine.com/parts/mariner-outboard-parts/30a/689250101-and-up-e/oil-pump

 

[airshot]

I was thinking about disconnecting the fuel line when the outboard won't be used for, let say a week or more, (two-three days tilted it starts fine, smokey though first 10 seconds), then I guess the check valve will be in use, with hose disconnected to the outboard, and neither oil or fuel can run back into the tank. With the hose installed there are no check valves in use and fuel and oil can run back into the hose and fuel tank.
Could E10 fuel have damaged something? E10 might have been used last year, no Ethanol blended fuel is used this year.
Anyone seen a maintenance manual so I can identify the components?
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Rather than jump to wild conclusions, why not trouble shoot to solve the problem.. Your comments about the fuel line should be pointing you in the right direction. It seems when anyone has a problem the first thing they blame is E10 fuel. Lack of maintenance far exceeds any issues from E 10.
Follow mfgrs recomendations and disconnect the fuel line from your engine when not in use, then if your problems continue, try your next step, but one at a time until you find your issue. Good luck....