2002 150 tach reading

[gstuck1956]

My Mercury 2002 150 today was reading 6500-7000 RPM when doing about 3000 RPM at idle it reads 1500-2000. Engine off it goes to zero. Can I get some pointers on where to start please. Both batteries are charging ok.
Kind of curious is I use it "as is" that at the end of July I am not going to get stuck 8 miles off shore at horn island offshore. Cant find a shop around here that is not a month or longer behind in work. I don't have a issue with spending 200-300 to get it right.

 

[fastjeff]

Was it always that way?

My tach did that when it didn't have a voltage regulator. Is your motor the same?

Jeff

PS: There's a switch on the back of the tach. It should be set on 6P. You might try wiggling it for a better connection.

 

[gstuck1956]

NO it just started jumping...also I have learned one of the 2 batteries is not charging. I have check all connections and found nothing. The switch is set correctly...I am putting shop shop on monday...I have done everything I can think of...Thanks for your help