'86 150 Mariner...when you turn on the power switch and the tach pegs out=goes down...does this probably mean that the tach is bad? When cranked it does nothing. Do you think it is bad wiring, not wired right or something else? Is there a way to check the tach to see if it is any good? Think the wires got messed up while steering cable work was being done. Thanks!

mine sets on 1k until i turn the key on and then it goes to 0 sent pm

try setting the switch from its current setting to another setting then putting it back to the original position, also remove, clean and reattach the sender, ground, and power cables. My tach was acting erratic, and this helped. There is also a second/alternate connection point, I'm not sure if it's on the engine or the tach itself, but there should be a cap or plug in the alternate connection you can replace and use. Sorry about the sketchy info, but the cleaning connections and switch movement worked for me, I didn't get to the alternate connection point portion of the plan.

Most shops have a test tach that can be connected at the motor to tell if your tack or wiring to the tack is good. Thats when the tach started acting up? The steering is under the console too and wires can be disturbed their. Could just be a rectifier-regulator going south.

They may not have re attached the ground if they replaced your steering (rack/rotary) helm.

Mine did the same thing peg out at start up then bounce all over the place I took the wires off the terminals on the rear of the tack cleaned them put them back on all was good, I also found what I thought might have been a loose wire but I cleaned them just the same all is well now.