1999 mercury 3 cyl 90 hp gauge wiring and controls

[sms986]

Picked up a boat with a 1999 mercury 90 on it.

I don't know the exact model, just that it's a 2 stroke 3 cyl. The tag on the transom plate isn't legible. How else can I ID this motor?

I've also got some questions on gauges and controls. I want to install a tach, water temp gauge, trim gauge, and water pressure gauge. There is a factory wiring harness going to the control box with a few extra leads. Which gauges are these leads for and which gauges do I have to run additional wiring for? Thanks!

 

[Chris1956]

Look for a silver disc on the head. It should have a serial number. You can look up the year on the maxrules web site.

Tachometer wire should be grey.

The motor would normally come with an overheat sender. Wire color would be tan.

Crowleymarine should tell you whether the motor came with a PTT sensor. They are unnecessary IMO. Trim is better by feel and sound.

Water pressure gauge is mechanical. See if there is a plug on the water jacket. A nipple can be installed to power the gauge.