tach quits at 4000rpm

[vaskeet]

finaly got to take my boat out for the first time after buying it a month ago. I have a few problems 1 the tach works good until around 4000 rpm then falls to zero the motor seems to run fine with no alarms any thoughts on this? 2 the speedo is inop where should I start to troubleshoot it? The engine is a 1988 evinrude 100hp model W100WTLM. there are a few other minor problems (livewells some other gauges ) the boat is a 1987 fisher sv-18gt which I got for 2000 my insurance company said it is worth 3500 so I am happy and will get it all fixed Randy

 

[emdsapmgr]

Re: tach quits at 4000rpm

Your erratic tach issue is likely your regulator/rectifier going bad. It is the watercooled box under the flywheel, mounted in the powerhead. It sends the signal to the tach. When it goes bad, it also will affect the charging of the battery, so keep an eye on the charge level till you are able to check the rectifier/regulator output and know for sure.