The bow water tank is always full

[Ailatan]

Can anyone help me?
I've realized that the water pressure pump only takes water from the transom tank. I followed the pipes and look in the owners manual and the only valve I've found is one just before the pressure pump with two positions, so I understand thi is to open/close the system.

Is there any valve to select which tank the pump takes the water from or do they both suppose to empty at the same time?

[Yngmar]

On our boat that valve is a three-way that selects which tank the pump draws from. Try it

Easy to tell because it has three connections!

[paulemeier1]

maybe with the wave you can choose front or rear tank? Or you have to follow the pipe from the front tank till this wave.

[tiger79]

As Yngmar said, with two tanks you should have a changeover valve, which has 2 inlets and one outlet.  The handle allows you to select which tank you draw water from.  Here's a pic of the valve on my boat for reference.

[Ailatan]

Thanks all for your answers and Tiger for the picture.
My valve is quite similar to yours. See the pictures (sorry for the quality).

According with your explanations I understand that with that valve I should be able to control from which tank the pump is taking the water, but in that position the pump should take water from both tanks because it is in the middle position but only the aft tank is emptied. Also I can move the lever to the right just 90⁰ but no more and 0⁰ to the left.
Is that normal?
 

[tiger79]

Also I can move the lever to the right just 90⁰ but no more and 0⁰ to the left.
Is that normal?

Yes, the lever only moves 90 degrees.  At one end of its movement it connects the forward tank, at the other end it connects the aft tank.

[Yngmar]

Same exact lever. It's even got an "L" written on it, meaning it's an L-Valve, which refers to the shape of the ball inside. It connects either one of the two intake pipes to the single output pipe. So in one position, it draws from tank 1, in the other from tank 2. It never draws from both at the same time because that cannot work if one tank is empty - it would draw only air and not work.

Illustration of an L-valve on the right:

[Ailatan]

There is nothing like to talk with experts!
Thank you gentlemen I thought I had to change the valve or something even worst!

[marioxp]

Thanks all for your answers and Tiger for the picture.
My valve is quite similar to yours. See the pictures (sorry for the quality).

According with your explanations I understand that with that valve I should be able to control from which tank the pump is taking the water, but in that position the pump should take water from both tanks because it is in the middle position but only the aft tank is emptied. Also I can move the lever to the right just 90⁰ but no more and 0⁰ to the left.
Is that normal?

Ailatan, my valve is like yours, have only two positions. Position one is for front tank and position two for rear tank, I can not close both tanks.

So, try move valve in second position I believe that water will be come from second tank.

Best regards,

[Ailatan]

Thanks Marioxp, now I can empty the front tank. The next problem is that tank is leaking

[marioxp]

Thanks Marioxp, now I can empty the front tank. The next problem is that tank is leaking

Why do you think it's leaking? Where is it leaking from?

How could it not leak before when it was full? This is strange to me.

[Ailatan]

Sorry I didn't explain myself.
At the beginning the tank was full but not completely full. Then when I understand how to empty the tank I did it completely in order to change the water. When I filled it again I saw some water coming out from the lower part of the tank but I think I already know where that water comes from