changing oil injection to premix

[sambrigman]

I have just purchased a 1988 40hp yamaha, I would like to change the oil injection to premix. I have been told that there is a shut down on the injection system that will have to be removed. Has anyone have experience with this conversion, suggestions about how to bypass the alarms and shutdown any help greatly appreciated

 

[alldodge]

I have just purchased a 1988 40hp yamaha, I would like to change the oil injection to premix. I have been told that there is a shut down on the injection system that will have to be removed. Has anyone have experience with this conversion, suggestions about how to bypass the alarms and shutdown any help greatly appreciated

Have a read thought this thread on THT.
http://www.thehulltruth.com/boating...jection-yamaha-150-hp-v6-2-stroke-2003-a.html

 

[Capt Ken]

Are you ready to change the jetting in your carbs also? Yamaha does not mix the oil with the fuel but injects it after the carb straight into the intake. If you premix then you need to install larger main jets or you take a chance of leaning out your engine.

 

[robert graham]

Are you ready to change the jetting in your carbs also? Yamaha does not mix the oil with the fuel but injects it after the carb straight into the intake. If you premix then you need to install larger main jets or you take a chance of leaning out your engine.

Just curious, but how does the injection/premix factor into the fuel/air mixture?....

 

[sambrigman]

Thanks capt ken for the info. So it looks like its to much trouble to change to premix, so this tells me how the oil is seeping in to the cylinders when the engine has set up for a while. I will have to continue to remove the plugs and blow out the oil .

 

[99yam40]

Thanks capt ken for the info. So it looks like its to much trouble to change to premix, so this tells me how the oil is seeping in to the cylinders when the engine has set up for a while. I will have to continue to remove the plugs and blow out the oil .

I would be checking on the check valves to make sure they function properly

 

[99yam40]

Just curious, but how does the injection/premix factor into the fuel/air mixture?....

SG of plain gas and gas with oil is different

 

[gm280]

I often wonder when I read folks changing over to premix in oil injection systems...WHY? If you maintain the oil system with regular yearly or sooner maintenance, why change over to premix? I'd fix the oiling system and love knowing that all I had to do was fill up the oil tank and the gas tank with gas and go boating and forget about proper gas/oil mixtures... Sounds like a great deal to me. So why would somebody want to stop using such a system? IDU... Curious!

 

[robert graham]

I often wonder when I read folks changing over to premix in oil injection systems...WHY? If you maintain the oil system with regular yearly or sooner maintenance, why change over to premix? I'd fix the oiling system and love knowing that all I had to do was fill up the oil tank and the gas tank with gas and go boating and forget about proper gas/oil mixtures... Sounds like a great deal to me. So why would somebody want to stop using such a system? IDU... Curious!

My 1999 C90 is premix and I like the simplicity of it....nothing to fail. When I gas up I add appropriate amounts of oil, Stabil and Ringfree according to what my intentions are....if it's the last tank of fuel for a good while I may heavy up on the Stabil dosage, once in a while I go heavy on the Ringfree to help shock off any carbon. Of course I'm used to this and it's not a problem to me....folks used to outboards pretty much taking care of themselves, just turn the key and go probably would never want to go back to an old/outdated premix motor.... For me half the fun of boating is screwing around with the boat, motor and equipment.....

 

[Capt Ken]

In 1988 I don't think they had yet started using check valves on the oil line. If not they are easy to install and will stop oil from bleeding into the cylinders.

 

[sambrigman]

Where can I find the check valve that I need? Thanks Capt Ken

 

[99yam40]

my best guess

6E9-13183-70-00 VALVE, CHECK

This should be the ones you would need, shows 3 starting in 1989 on the 40
They show up on 25s and 30s in 1988,
do not know why not on the 40s

 

[sambrigman]

Thanks so much for the info.