Tach Problems Force 150 hp

[panther150]

I bought a new tach for my boat a couple of years ago for my force 1991 150 hp. 20 pole. Almost always works when I start the boat but cuts out when RPM is increased. Sometimes the needle will bounce around as if there is a short in the wire and sometimes it will function well for short periods of time at higher RPMs. I tested the wire from the engine to the tach and replace the tach itself and it still does the same thing. Tach seems to work better in cool weather. What components could I test to find out where the problem is and how can I do this. I have books and manuels for this engine but nothing refers to this problem.<br /><br />I am new to this forum and would appreciate any help. Thanks. jm

 

[WillyBWright]

Re: Tach Problems Force 150 hp

Welcome to iboats. <br /><br />Make sure your battery connections are clean and tight (not just finger-tight). Make sure all the connections to the voltage regulator are clean and tight including the mounting hardware. Make sure the instrument wiring harness connection out of the remote control is clean and secure. There may be a rotary switch on the back of the tach, make sure it's firmly in position.

 

[panther150]

Re: Tach Problems Force 150 hp

Checked out all of your suggestions. Tach is still a problem. Any other ideas? jm

 

[force 150 fl]

Re: Tach Problems Force 150 hp

Checked out all of your suggestions. Tach is still a problem. Any other ideas? jm

I also have a 1991 150 my force that has the merc thunderbolt charging system on it with same problem . check the voltage reg it provides the tach voltage and will still charge bat 13 -14 volts but give wrong rpm values . I replace my reg twice in 13 yrs and both times it effected the tach . The second time the tech gave me advance notice of reg failure . When it starts to give wrong rpm readings intermittentley I know it's starting to go bad now . they Also they make a few reg for that engine beware !!!! Be sure all connections are tight and backboard is grounded good !! I have notice that running two bat system on that charging system seem to make my bat last longer and dont over charge them if you do a lot of offshore running . I run that engine 25 miles off shore in salt water for 13 yrs and still going ! good luck and keep a tight line Jb

 

[panther150]

Re: Tach Problems Force 150 hp

Thanks for the info. I will check the regulator.

jm

 

[stevecut]

Re: Tach Problems Force 150 hp

maby you don't need a 20 pole tach. when I changed my motor from a 89, 85 horse to a 95 120 horse I needed a diferent tach. call a boat store there special orders department will call mercury and see what tach is needed for your motor. thats how I found out.