Crazy Tachometer Problem

[cestlavie]

Okay I bought a 1987 Four Winns Sundowner with a 4.3L mercruiser I/O. The tach did not work when I bought the boat and it is made by Medallion. I contacted them and they were able to repair it and send it back. I installed and initially it worked and then all of a sudden the needle disappeared under the plexiglass. I removed the front plexiglass face and saw that the needle moved 180 deg opposite to the position it is suppose to be and it is acting like it is running in reverse. Is there any wiring issue on the boat that would cause the tach to behave this way. I know I wired it up properly and verified that it was set for 6 cyl.

 

[alldodge]

Re: Crazy Tachometer Problem

:welcome: to iboats

You have a hot wire (Purple), a ground (Black) and a lead from the - side of the tack (Gray). Other then that it could have a switch on the back to select between 4, 6 or 8 cylinder engine. With it running backwards check to make sure the wires are not hooked up incorrectly. Since this is a bpat new to you do not rule out the previous owner may have been a self professed rocket scientist.

 

[cestlavie]

Re: Crazy Tachometer Problem

Yup, I have the purple wire hooked to the positive side, the black to GRD and grey goes to the SIG. Now I did notice that the grey wire the insulation was bit ratty, I was going to tape it up, not sure if this is the cause. There is a dial indicating 1, 2, 3, and 4, I have it set to 3

 

[alldodge]

Re: Crazy Tachometer Problem

Been looking around on the Medallion gauges and the tach seems to have the most issues. The website is basically a waste of time unless your looking to but or want to send them a message. The setting of 3 appears to be correct. Since you just had it repaired I would suggest asking Medallion if they have an answer.

Wish I could be of more help but there is just not much out there to help.