1996 115hp oil injection problem

As the heading states I have a 1996 115 outboard that has neve given me a moments problem. When I put the boat away this fall it was running fine no issues, When I took it out of storage I noticed oil around the ground, i didn't bother checking what oil had leaked. Since the engine has never had a tune up I brought it to the Yamaha dealer and had them check the lower unit assuming this is where the oil had come from.

I received a call a few days later, the carbs and entire engine compartment was full of 2-stroke oil. As a note, when I put the boat away I removed the batteries so what ever was causing this is not electrical. The tech did the tune up but could not find anything wrong with the oil system. I brought the boat home, it ran fine but has been up on the hoist since it was worked on. Tonight I started it. It obviously had a lot of oil in it again as it was smoking like crazy. A quick run cleaned out but obviously the problem is still there.

Any thoughts on what could be causing this?

Thank you in advance.

Scott

[boats.net]

Remove oil pump and check oil seal in back of oil pump, check inline check valves in oil injection hoses to each cylinder.

Remove oil pump and check oil seal in back of oil pump, check inline check valves in oil injection hoses to each cylinder.

ok, that make sense. I will, thank you.

Scott

A little more help

Prior to ordering the parts recommend. I pulled the cover off last night. The oil holding tank on the motor is full right to the top instead maintaining a level between the lines as it is suppose to do. Would this still be a result of bad chack valves and or a problem with the oil pump seal?

I just don't want to start throwing parts at this.

One other thing, with this issue once the oil was cleaned out I have been able to use the boat, Smokes a little at start up but otherwise runs fine. Last night one of the lower cylinders was full of oil. I assume what ever is pushing the oil through the system is causing this. I just wanted to mention it in case it helps narrow down the problem.

Thanks again
Scott

[boats.net]

If the oil tank is overfilling it will force oil into air silencer on front of carbs. The oil level sensor in engine oil tank could be bad.

[rwwillhunt]

A little more help

I had a similar problem several years ago on my 86 115 engine. I had oil getting in the lower cylinder to the point it would not turn over til I removed the spark plug and turned it over blowing oil all over the place. It would then start smoke a lot and run fine till it set up for awhile. I was told I needed to replace the oil pump as the check valve was bad. I replaced the oil pump and it did cure the problem for me. I used the same lines and only replaced the oil pump.

The second issue I have had is oil coming out of the motor tank when the boat would set for a length of time. This would only happen on one motor. I finally figured out the remote oil tank was higher than the motor tank causing it to siphon on its own. I lowered the remote tank lower then the motor tank which stopped that problem. I don't know if this will help but that has been my experience on what sounds like a similar problem.

If the oil tank is overfilling it will force oil into air silencer on front of carbs. The oil level sensor in engine oil tank could be bad.

I don't imagine there is anyway to test this other than to just replace it?

Thanks for the help.

I had a similar problem several years ago on my 86 115 engine. I had oil getting in the lower cylinder to the point it would not turn over til I removed the spark plug and turned it over blowing oil all over the place. It would then start smoke a lot and run fine till it set up for awhile. I was told I needed to replace the oil pump as the check valve was bad. I replaced the oil pump and it did cure the problem for me. I used the same lines and only replaced the oil pump.

All of what you had sounds familiar to what mine is doing. What I don't understand is how the pump could be causing this if it only happens while it is sitting. It even did it over the winter (to a lesser extent with no batteries in it).

The second issue I have had is oil coming out of the motor tank when the boat would set for a length of time. This would only happen on one motor. I finally figured out the remote oil tank was higher than the motor tank causing it to siphon on its own. I lowered the remote tank lower then the motor tank which stopped that problem. I don't know if this will help but that has been my experience on what sounds like a similar problem.

I am going to have to check this. With the boat on the hoist if I leave the motor down the tank could be lower since the hoist tips to the rear a little.

Thanks I will check this out.

Scott

Ok, so heres the deal. Clinging to the little bit of hope I have that this is anything but a major problem. This has been a great running boat since day one last year was the first sign of this issue appearing, so what changed?

Last spring I pulled the center pontoon out, lowered it 2" and moved it back 18". Last year my hoist was fairly level for most of the year, this year is tips back a lot more. Taking a good lok at it the oil reserve is if not lower than the tank on the engine it is very close. What else do I know? After the mechanic cleaned up the mess and the carbs it ran pretty good, I had the hoist fairly level. Then I moved my hoist back and lowered the back to make it easier to get on and off. A few days later using the boat it smoked a little starting it up. Not a lot but a little.

Later that week I filled the oil reserve. Next use of the boat and the engine is again full of oil.

Tonight, I pulled the oil reserved and moved it to a spot lower than the engine. I took about half of the oil out of the tank on the engine, cleaned up the mess again. When I hooked the batteries back up the motor on the reserve tank ran until it filled the engine tank to the high level and shut off so that seems to be working ok. I guess all I can do now is give it a few days and see if the engine tank fills on it's own again.


I will post the results.

Scott

Update......success

Lowering the reserve tank seems to have done the trick.

Thanks for all the help.

Best Regard
Scott