2007 Yamaha 25 two stroke oil injection

[Av8erdunn]

I just bought a 2007 25 two stroke to use on my dinghy and have a question in regard to the oil pump. The previous owner didn't use the oil injection since he didn't trust it but I know yamahas have a proven track record therefore I would like to use it. I have taken the pump apart and cleaned it along with replacing all lines and check valves in the oil system. I am running premix at a 100:1 mixture until I am sure the injection is working as it should. The confusion is when when I see oil traveling up the clear line to the injection point before the reeds. It actually pulses the oil up the line moving about an 1/8" up the line at each pulse with a 3-5 seconds between pulses with the throttle set to start position. I have run it like this and I have a surge in rpm while cruising which seems like it is happening every time it injects oil. It would make sense because it goes from lean to rich which will cas engine rpm to change. Is this the way the oil injection should work pulsing oil up the line in short burst?

Thanks in advance for the help

[amahaork]

don't know timing, but it pushes oil painfully slow, that's why after repair or extended storage it is advisable to run engine on premix at list for hour or until all air purged from tubes. i run all season on premix in addition to oil pump, and examined spark plugs frequently - they were ok, no extra carbon.
it is probably paranoid and add extra expense for Yamalube, but that's me.

[Av8erdunn]

I figured it would be more of a constant flow with speed of flow varying with rpm but this is a start and stop type of thing every 2-3 seconds when it's running at about 1500 rpm.

[rodbolt17]

and that's how this cam operated pulse pump works.
its a piston driven off a cam.

[Av8erdunn]

and that's how this cam operated pulse pump works.
its a piston driven off a cam.

The oil injection pump is a screw type pump. The engine rotates the gear (shaft) from the side of the powerhead whichsits inside of the oil injection pump itself. The gear then spins a screw type pump to feed the oil to the engine. This pump does not have a cam in it to operate the pump. The only Cam in it is used for metering the amount of oil flow.

[boscoe99]

What is the complete model identity for the motor?

[Av8erdunn]

2007 yamaha 25msh

[boscoe99]

It is hell getting old with my vision not being what it once was.

Here is a link to the parts catalog for your model. Where is the oil pump depicted? Damn if I can find it.

The cowling does not show a port through which an oli tank could be filled. I can't even find the oil tank.

2006 and Later 25MSH Yamaha Outboard Parts

[Av8erdunn]

Thats one of the things I was having a hard time finding was a nillustrated parts catalog with the oil pump and tank depicted. The cowl has to be removed in order to fill the oil tank on these smaller motors. My buddys 30hp is the same way.

Here is a link to the exact system thats on my 2007 25HP. Not real sure why its not shown on there.

OEM Parts)

[99yam40]

Your link does not take me to anything but the parts look up page that needs info to see a certain motor.
You will have to tell us what motor you looked up to get to the diagram

[Av8erdunn]

25mshu2 - 1996

Or this as they are the same.

http://www.boats.net/parts/search/Ya...ION/parts.html

[99yam40]

Those parts show only for 1988 to 1997 here in the USA.
Maybe Rod know something more than you think.
What country are you and this motor from?
If not US then our part system may not show what you are looking for

[Av8erdunn]

I am in Mobile Alabama. I have had the pump apart on this thing and they are the same design as the one shown. Not sure why it doesnt show it used on other years.
I am at a loss.

[boscoe99]

I hate to ask so many questions but what is the complete serial number for your motor? It will begin with the number 6.

As a tie breaker you might want to call Yamaha customer support to see if your pump pulses oil or feeds it continuously.

I am out of the country and am limited to questions that I can answer. I am perplexed about a 25MSH having an oil pump.

[Av8erdunn]

I hate to ask so many questions but what is the complete serial number for your motor? It will begin with the number 6.

As a tie breaker you might want to call Yamaha customer support to see if your pump pulses oil or feeds it continuously.

I am out of the country and am limited to questions that I can answer. I am perplexed about a 25MSH having an oil pump.

I'm not home now but I will look at it later. Now you have me worried that someone may have put different brackets with the data plates on them at some point. The cowl sure looks like a newer rounded style. Not the old boxy style. Could they have put a newer cowl on an older motor?