03 150 xl efi 2-stroke 2.5L (0T409000 THRU 0T800999)

[demarko210]

While looking my engine over I notice that I have 2 sensors. One has a water tube connecting to the bottom of the engine with a T-fitting. The other half of the T-fitting goes out of the engine through the rigging tube and is plugged. This I assume goes to the helm to give the water pressure within the engine to a gauge. The second sensor does not have a water hose connected to it. It just setting there connected to the engine harness without any water tube. I have looked at the parts catalog for the engine and it does not show how or where the tube run for either sensor. Parts catalog image attached. It is number 17 and 18.


The second image is of my engine. The sensor on the left does not have a water tube connected to it.


Does anyone know what this second sensor is used for? I tried looking at a different parts diagram for the water hoses which is the 3rd image. It only show that there is one hose for the engine. Usually if I needed 2 hoses it would list quantity as 2 but all you see is 1 on the list. Number 7, 6, 8, 12


Let me know if anyone have any idea...

 

[dingbat]

According to the parts list one is water pressure the other is oil pressure,prat least it seems

 

[demarko210]

Thanks Dingbat,
That would make sense oil pressure sensor. I would think it needs to have a tube connected to it to function and transmit data to the ECM, but its a water tube not a oil tube. Other than that it would be getting NULL data. I do not see anywhere in my Selco or Merc website saying where and if there is a connection to the bottom inlet. I meant to contact Mercury yesterday, they are very helpful answering questions. I will update when I talk with them.

 

[demarko210]

Called Mercury again hold time was not long. They told me the right sensor is for the water pressure and the left sensor is for the speed tube to connect to the dash.