Yamaha Precision Blend questions

Big.Band

Cadet
Joined
Dec 4, 2018
Messages
12
Hey everyone - I've been 'lurking' on this site for a long time, and finally need some help.

I've purchased a 1992 30hp with "Precision Blend". The guy I got it from was using gas/oil mix in his fuel tank, but the on-board oil tank has oil in it. He only had the motor for a short time, and didn't know much about the precision blend system
I figure that either the precision blend system was not working, so he pre-mixed his fuel, or if the system is working, his motor was getting double oil.

- How can I test the precision blend system to see if it's working?

- I assume there is some kind of 'low oil' warning system?

- What is the best source for an OEM manual for this motor? Anything available for free download?

Thanks !
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,043
Mark the oil level in the tank.--------Run the motor on 50:1 and see if oil level drops.-----Or see if oil drips out of the wee hoses from the pump.
 

Doh

Petty Officer 2nd Class
Joined
Aug 12, 2008
Messages
187
The Oil Level Sending unit is in the tank, attached to the rubber plug with 2 wires coming out of it. It is just a float that could be fooled so that the tank wouldn't need to carry oil.

It is a pretty fool proof system, I cannot see Why the pump would stop working.
 

Big.Band

Cadet
Joined
Dec 4, 2018
Messages
12
Mark the oil level in the tank.--------Run the motor on 50:1 and see if oil level drops.-----Or see if oil drips out of the wee hoses from the pump.

Pardon the newbie question, but what's a "wee hose" ?

Also, does this motor want 50:1, or 100:1 ?
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
It should go without saying that until you determine the operation of your oiling system then pre-mix your gas/oil at 50:1 ratio....it won't hurt the motor if there's extra oil....just maybe more smoke...
 

Big.Band

Cadet
Joined
Dec 4, 2018
Messages
12
It should go without saying that until you determine the operation of your oiling system then pre-mix your gas/oil at 50:1 ratio....it won't hurt the motor if there's extra oil....just maybe more smoke...

That makes good sense, thanks for the clarification.
Is there any source of free OEM service manuals out there in the internet?
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Yea! The on-board oil pump is working fine. Thanks everyone!

Much better, lower, middle rpm ranges requires way less oil than running 50:1 mixture constantly throughout the whole throttle range. Spark plugs will work better and stay cleaner longer.

Happy Boating
 
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