1994 Yamaha 2- Stroke 150 hp Pro-V issues

I bought a new to me boat last fall and I am having issues with the engine, it periodically leaks oil from the oil reservoir. This has happened a couple times this spring. Fast forward to Monday, I was trolling and the high temp. warning siren stated going off (never happened before), I shut down the motor, started it back up still beeping, checked to make sure it was pumping water and it was, shut down again. Let the motor sit for about 15 minutes and started it again, no warning beep, trolled for another 10 minutes and the high temp. warning again, shut it down and took off the cover to find oil overflowing the reservoir and coming out of a small black tube which I am assuming is an overflow tube. Let it sit for 15 minutes again, started it back up and got back to the landing going a little faster with no over heating but still leaking oil. Any ideas

I justed googled (1994 Yamaha 150 pro-v) There are other people that have had some of the same problems!

If it was mine I think i would replace the check valve or oiler fitting where it dumps into your gas line, your motor may not be getting the oil it needs a slow RPM’s thus alarms going off, or you can take it to your local dealer & have him completely take oil resivour (sp) out & mix your gas & oil right in the tank that way you know its always getting oil! hope this helps. good luck!!

I had a problem with a 95′ evinrude having a bad sensor in the oil resevoir. Motor chugged over 5mph and alarm would go off.

A buddy of mine that works on outboards actually just did the job of disabling the oil injection on a guys boat because it was pumping way way more oil than it should have been. Apparently its much better to mix it yourself because you can’t be sure that it is injecting the correct mix of oil. Not sure if this is a problem with newer motors as well, but he said older motors it is common. I never considered it, but im still running mine with the oil injection because it seems to run fine the way it is.

Talked with a marine mechanic last night, he thinks the oil issue is a sensor and the over-heating is impeller/water pump, hopefully this will take care of it. Thanks for the input.

I agree the overheat is the impeller. I have a 1995 175 Pro V and had the same symptoms as you are experiencing. The impeller can take a set if sits too long.

I know I am reviving an old thread, and I apologize in advance. That being said, what was the root cause of your oil issue?

I am experiencing the same thing on mine. Same year, same size. Motor starts smoking, gets thicker and thicker until smoke bubbles begin to surface, and engine begins to run very rough. I shutdown at that point and see the fresh (blue) oil on the water’s surface, when tilted up it drips into the transom, and runs down the lower unit after being pulled from the water. The lower carbs are dripping the unused oil.

This has now happened three times. First time was two years ago. Once earlier this summer, and now again this past weekend. Not many hours between numbers 2 and 3.

OK now you are testing my memory. I believe it ended up being a float stuck open which just allowed oil to pour into the on-board reservoir. Between replacing that and the water pump/impeller I have not had further issues. I still own the boat and the motor is running great. Good Luck.

Appreciate the feedback. Perhaps you can dig in a bit and send me a PM with more detail? I have taken the float apart and it moves quite freely, and does appear fairly clean.

Thanks again. Motor runs great when I’m not smoking like crazy!