Yamaha 90HP (2004) Oil system

[Jim Hawkins]

I just got a boat with a Yamaha 90HP 2 stroke and am checking things out before I use it. The first thing I want to check is the oil injection and the warning indicator specifically. I've done a good bit of reading on the system and understand it is considered very reliable so we've got that out of the way. This is not a thread about the option of disconnecting it.

I pulled the oil reservoir and with the filter/sensor out of the tank I assumed a warning would sound if I turned the key on, but there was nothing. My gauges do not have the fancy lights like the manual shows.

Can anyone help me with a procedure for testing the warning system?

 

[Jim Hawkins]

OK, so maybe another question on the more exciting topic of disconnecting the oil injection.

Instead of dismantling the whole oil injection system why can't I just simply cap off the intake to the oil pump?

 

[99yam40]

to test you drain the tank with the key on to see if the alarm comes on.

you always need to drain the tank before removing the level float switch and screen.
make sure you do not get trash into the oil pump while they are out and make sure you get them set back in properly before adding clean oil back in.

 

[Jim Hawkins]

to test you drain the tank with the key on to see if the alarm comes on.

you always need to drain the tank before removing the level float switch and screen.
make sure you do not get trash into the oil pump while they are out and make sure you get them set back in properly before adding clean oil back in.

Thanks 99 but I guess I wasn't clear. As I said in my post I already pulled the reservoir (after emptying it) and the filter/sensor was out of the tank and no alarm sounded with the key on. What I was hoping for was some direction on what/where is the alarm/indicator, can I apply a voltage to a certain wire to test, and, and

and it's becoming more and more clear, this just isn't worth it. I've made up my mind. I'm going to drain and remove the tank and cap off the inlet to the pump and in the future I simply pour oil into a different opening.

 

[99yam40]

without gauges to show what is happening when low oil or overheat happens then the only thing that should happen is the buzzer behind the key switch should sound and RPM will not get above about 2000.

You need to make sure the buzzer works before saying the oil system alarm does not work.

If you want to know if the oil injection works you will need to mix oil in gas and mark oil level in tank and keep an eye on how much it moves when you run some gallons thru.
and /or the service manual will have a way to test/measure the output in CCs over a period of time at a certain RPM

these oil systems (Yamaha) are very good. just need to make sure it works as it should and keep it clean. anything neglected will bite you somewhere down the road

You are right I thought you removed the tank and sensor from the motor so it will not work if not attached

 

[Jim Hawkins]

Thanks again but my mind is made up to disable the oil injection. Is there any reason I can't just drain the tank and cap off the inlet to the oil pump?

Here's where I am, I cleaned the tank, inspected all the tubes and added a new clear tube to the top carb so I could actually see the oil flow. The old tube was stained and no longer clear. Then I read that the system must be purged of air so I researched how to do that. I bled oil to the pump using the bleeder screw and attached a tank of premix to the motor, BUT before starting it, it occurred to me that the motor will be running for several minutes on straight gas until until the fuel in the carb bowls and hoses is used up. I then drained the bowls and pumped premix through the system until all the old fuel was gone. But this was the point where I started to think about eliminating the system. Why, in all I read did Nowhere mention purging the carbs and lines of straight gas. Seems to me following the given procedures I found online exactly would have really hurt this motor. After that, I couldn't get it out of my head, What else are they not telling me? What else can go wrong? And knowing how liquids come out of a tube in drips and blobs, how on earth could this system mix fuel and oil as well as premix?

Really doesn't matter because I am not going to be the 1 in 1000 that ruins their motor for lack of oil, so,
Is there any reason I shouldn't just drain the oil tank and cap off the inlet to the oil pump as a method to disable the system?

 

[99yam40]

with out oil flowing thru the oil pump (for lubrication) that is geared to the crank shaft there is a good chance you will destroy something

 

[Jim Hawkins]

with out oil flowing thru the oil pump (for lubrication) that is geared to the crank shaft there is a good chance you will destroy something

ah ha, so, I can cap off 2 of the oil tubes and leaving a little oil in the tank run the 3rd tube back into the tank. Or, disconnect all 3 lines at the check valves and turn the check valves around and put them back in the hoses that lead to the carb to block them then take the 3 loose ends coming from the pump and direct them back into the tank.

Unless, is it possible to access the oil pump to remove the shaft inside without having to dismantle other things and is that easier than the above scenario?

(Thanks for hanging in there with me 99)

 

[Capt Ken]

Little knowledge is very dangerous. The oil pump doesn't mix the oil with the fuel, it injects it directly into the intake. The carb is not jetted to run premixed fuel like the C model engines are. Idling the engine while waiting for the oil to fill the lines will not damage anything. Do not remove the oiling system unless you are prepared to block off the hole where the oil pump mounts and rejet the carbs.

 

[Jim Hawkins]

Sounds like you know what your talking about. When re-jetting the carbs, what are the specs on the jets for straight fuel as compared to premix?

And do I understand right that running a 2 stroke motor at idle for 5 to 10 minutes on straight gas wont harm it?

 

[99yam40]

usually you use some premix until you know for sure the oil system is bled and functioning properly,
He just said to run at idle while bleeding the air out

 

[Jim Hawkins]

usually you use some premix until you know for sure the oil system is bled and functioning properly,
He just said to run at idle while bleeding the air out

Maybe I misunderstood, I thought that was in reference to what I said about not seeing anything anywhere about empting the carb bowls and fuel lines of gas without oil and then pumping in premix. If you simply plug in a tank of premix the motor will run for quite a while on the straight gas left in the carb bowls, fuel filter/water separator and fuel hoses.

"" Idling the engine while waiting for the oil to fill the lines will not damage anything. ""

 

[Jim Hawkins]

No Title

Well, I did the dirty deed and I did it my way. I cut all 3 oil tubes in the area of the fuel filter and using plastic T's I first joined the tubes going to the carb to cap them off and then combined the tubes coming out of the pump to a clear tube pumping oil back into the tank through a hole I drilled.

The system is still in place and can be redone with 3 simple plastic splices
The oil pump gets it's lubrication because there is still oil in the tank and
If I ever need oil while on the boat I have a surplus supply in the tank which can be accessed by simply disconnecting the large clear inspection tube from the top of the tank and lowering it to allow oil to drain.

The pictures tell the story.