Tach went screwy

[DangerNewb]

Just mounted a 300 Promax to my hull. Yes, it drinks gas as everyone told me it would...

Anyhow, first time out, the tach worked well. Reading 5500 or so at 80-85 mph with a 32 prop and 1.75 gear case. 4k was bout 50mph if I recall correctly.

Second time out, 4k is 40mph and saw over 6k rpm at 70-75. Tach jumped around some. Motor should redline at 6200 or so and should be doing mid 90's over 6k rpm so something has gone wrong.

Anything I should try before I assume the tach lost it's mind and replace it?

[vnemous]

twist the dial on the back that has the pole positions back and forth a couple times than set it back to what it was on. This often fixes an errant tach. JMO

[DangerNewb]

Thanks. I'll give it a try. Will take my phone with me in case I need to call for help extracting myself out from under the dash. Or bite the bullet and remove one of the seats from the sliding mount. Not much room in my little rig.

[tux974]

It probably has gone into shock with the 300....JK;):D

Also make sure you have 12+V, your wires are tight especially ground and harness connection at motor.
BTW, they do drink at WOT, mid range should not terrible for 300.

[gmacrae]

if it's anything like the older motors the grey wire at the voltage regulator/rectifier is your tach signal... bad reg can make the tach signal go nuts... but yeah sorry I got no idea if your 3L is remotely similar!