Temp and water psi gauge help 225 merc efi

[bsullivan403]

I recently bought a 2002 merc efi 225. I've never owned a merc so this is all new to me. I'm looking to hook up a water temperature gauge and a water psi gauge. I've been searching the Internet for 3 days and can't find an answer.
1. Are these motors prewired for a temp gauge? Heard mixed things
2. Where do I connect the hose for the water psi gauge?

[Mini GT]

Water pressure hose needs to be connected to the top of the block. There is a fitting about 2" behind the flywheel if you are looking from the stern, right at the apex of v block.

[bsullivan403]

Thank you! Ill get the fittings for it.

[vnemous]

If its a three liter 225 its on the bottom of the rear of the block.

[Mini GT]

Good add. Should be able to get these fitting from HomeDepot......post a picture when you are done.

[bsullivan403]

It a 02 225 merc efi saltwater series. I know very little about this motor but I believe it's a 3L

[bsullivan403]

Bottom of the port side? I saw a large brass plug there. Gotta remove the lower cowling to get to it?

[vnemous]

no thats in the exhaust plate. Its above that on the back of the block low just above the cowl. Might have a 1/4" plug in it. Near the fittings for the pisser and flush attachment

[bsullivan403]

ok thank you! Do you know if these motor are prewired for a temperature gauge in the wireharness?

[vnemous]

yes its a tan wire going to a sender in the head. Starboard head, should have two wires one is ground (black) the other is tan.

[frederick55]

yes its a tan wire going to a sender in the head. Starboard head, should have two wires one is ground (black) the other is tan.

Don't know if they are the same setup, but on Omc the temp senders on the heads are for the alarm: they don't read temp for a guage. I added separate temp sensors for each head to run to two guages. Had to run separate wiring, and left the alarm horn operating also.

[vnemous]

temp sensor is on the starboard head. There is a separate sensor for alarm. I just looked at a 225 efi in the shop. There is a plug in the middle of the lower block in the exhaust chest for water pressure. There may be a bigger brass plug on either side.

Ok its either the sender #40 in this pic. Starboard head
http://i260.photobucket.com/albums/ii3/vnemous/19116_zpsc61d34c6.png (http://s260.photobucket.com/user/vnemous/media/19116_zpsc61d34c6.png.html)

Or sender #14 note #42 is seperater for alarm in this pic.
http://i260.photobucket.com/albums/ii3/vnemous/23803_zps11fd52e2.png (http://s260.photobucket.com/user/vnemous/media/23803_zps11fd52e2.png.html)

[bsullivan403]

I see the sensor on the block I just don't have the tan wire coming out of the wire harness under the dash. As far as te water psi I see the outlets on the bottom rear of the block. One runs to the top of the motor to a sensor and the other squirts out the back of the motor. Can I just "t" into the side that squirts out the back of the motor?

[JohnR]

There's no pressure there, the hole it pees out relieves any pressure. Been there, done that. :)

[vnemous]

John this is where its at.
295037

[vnemous]

Back of my 300x looks like this. The line comes out right below the center of the first two coil drivers into a t and than one to the gauge and one to the sender for computer. Single computer

295038

[peterbower]

I recently bought a 2002 merc efi 225. I've never owned a merc so this is all new to me.

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