Mercury 9.9 Reed Valve and Check valve question.

[w2much]

Model # 1010201YD , Serial T372846 , 2001 Model 2 stroke MH.
A couple of questions answers requested. The cylinder block and crankcase diagram does not show a gasket between the reed block (part # 828435A3) and the crankcase. Is this correct? The older model 9.9 did have one here.
At some point part # 828435A3 was reconfigured By the manufacturer I guess.
Reference the 1995 Mercury 9.9 Model 1010201RB. This diagram shows two differing reed block assemblies with and without gaskets seals ect. So If I am confusing you I apologize but once again I too am confused.
Gaskets or not on my 2001 with the rubber coated part # 828435A#3?
Also in reference to the parts diagram for the 1995 9.9 Model 1010201RB there is a check valve part # 13 on the diagram manufacturer part # 42657A3. This check valve is not referenced in the parts diagram for my 2001 Model 1010201YD .
Now then if the check valve is bad on my 2001 can it be replaced. It is referenced and sold seperately for the 1995 model but does not appear in the diagram for the 2001 model.
What is the function of this check valve. I see that there is hose fitting on the carburetor. This fittings hose T's off to the crankcase, to each cylinder. With the carburetor gasket in place the hose is actually not a factor with the carburetor at this point. Not from the fitting anyway. The hoses and the fitting actually provide to the reed block, not the carburetor even though the hose fitting is on the carburetor. So my question is what is the function of the check valve? And what occurs or does not occur if this check valve is failing?
I hope this makes sense to those reading it as it does require a lot of knowledge or diagram cross checking to follow. Thank you.

 

[w2much]

OK. So I am pretty certain that the fitting on the bottom of the carburetor provides vacuum to the carburetor or the pulse for the fuel pump. The check valve is one way. Mine was bad. The engine will not start or run if this valve is bad. A 5.00 part had me running back and forth between ignition and fuel delivery.So my check valve is bad and needs replacement. I am hoping that with the newer model reed block the check valve can be replaced without having to replace the whole reed block.

 

[racerone]

A " one way " check valve would not be used to operate the fuel pump !!

 

[w2much]

OK. Now I know that. Better yet I know why I think. Because it will provide a vacuum not a pulse. Is that correct.? Thank you. .

 

[w2much]

Is that valve usually replaced or is the whole reed block replaced. The valve is sold seperately as it is used in both the new and old style reed block of the same pat number. If replacing is it just a knock out then apply a sealant? My manual just says to inspect it . A Mercury manual is on the way.

 

[racerone]

????------An outboard fuel pump works on posive and negative pressure pulses !------A check valve only allows air to flow one way.-----And that is not PULSING !!

 

[w2much]

I realize that but the hose that Ts off goes to the carburetor and does pulse does it not. The check valve is on the reed block up against the carburetor. If not where does the fuel pump, attached to the carburetor get its pulse from?

 

[The Force power]

Can you send a pic. of the Carburetor?

 

[w2much]

I am sorry I do not have a picture. The year and model number are stated if you would be inclined to look up the part.
Has any person changed this one way valve or do I need a new reed block. As I mentioned previously the check valve is listed seperately on the older model 9.9 but not on the newer model . That is the question. I dont care whether it is vacuum or pulse, I just need the valve to function.

 

[The Force power]

For some reason, I can not copy & paste a pic. below is a link to what I think is your Carburetor

https://public-mercurymarine.sysonli...=englangDB=eng

this may also not work, try this;https://www.mercurymarine.com/en/ca/parts-and-accessories/parts-catalog

 

[flyingscott]

The fuel pump on your motor is part of the carb. It gets its pulse through the carb body itself, The base of the carb has a hole in it that corresponds to a hole in the mounting base of the block. The line you are looking at with the check valve is a re-circulation line. It pulls puddled up fuel from the bottom of the crankcase. It does this by using the positive pulse from the crankcase to push the excess fuel into the line. That is why the check valve is there it prevents the fuel from being pulled back into the crankcase. I have never seen one go bad. The reason the parts are listed for the earlier 9.9 motors is because they are built on 10 cid blocks. The later ones like yours use the 15 hp 15 cid block.

 

[The Force power]

Ohh, is that check-valve w2much is referring to, now I understand also.

flyingscott, just out of curiosity; is with this motor the re-circulated oil re-routed to the top main-bearing for lubrication & re-burn?

 

[w2much]

Yes yes and yes. That is what we are talking about. And now I know what is does. I have not seen one go bad until this one.I hooked a hose to it. Sometimes it sticks, I do not know how but it does. When it does I need to unhook the hose at the T going to the carburetor(and the check valve), then suck and blow on the short hose until it seems to seat itself. When the check valve is properly operating the engine runs fine, when the valve sticks open it will not start. I have one ordered, Can the old one just be knocked or drilled out and replaced or will I need to purchase a new reed block? Thank you for your replies.

 

[The Force power]

No, I'm pretty sure the pulsation is through the port holes in the main block below the intake, the oil return line is (i guess) connected to the carb. ??

 

[flyingscott]

No, I'm pretty sure the pulsation is through the port holes in the main block below the intake, the oil return line is (i guess) connected to the carb. ??

That is.not how those motors work! The pulsation for the fuel pump goes THROUGH the carb body, no hoses at all. Besides how can a pulsation line have a check valve on it. With a check valve it either becomes a pressure or a vacuum line depending on orientation of the check valve.

 

[flyingscott]

I would try cleaning the valve with carb cleaner when it gets stuck open. But that problem should not make it not start. You MAY have a lower crank seal problem ,it will be up to if yoi want to pull the powerhead or not.

 

[w2much]

You are right again. I do not want to pull the powerhead, but will if I have to. I will try cleaning the valve and running the engine this weekend and post results as I go. Thank you .

 

[The Force power]

That is.not how those motors work! The pulsation for the fuel pump goes THROUGH the carb body, no hoses at all. Besides how can a pulsation line have a check valve on it. With a check valve it either becomes a pressure or a vacuum line depending on orientation of the check valve.

That's what I was saying "through the Carb body/ porthole" and I'm not saying the oil return line is connected to the Carb.
I was wondering about that?? because that did not make any sense

 

[w2much]

Today I received both the Mercury manual and the check valve. The manual states that the the reed block is not serviceable. If there is a problem it must be replaced in its entirety. So I went against the grain and pressed out the check valve and pressed in the new one. The motor started right up. I ran out of time .I will lin k and sync , time and adjust tomorrow and post the results.

 

[w2much]

After the linc and sync the motor runs great. The check valve was definately bad. I am guessing that being out of sync altogether made it hard to start so that the fact that the check valve was bad compounded the issue by allowing too much fuel to puddle in the crankcase.. Thank you for your inputs.