rpm gauge not working

[Steve Gibson]

I'm having a problem with the tach not working on my 98' 640.It all started when i changed the prop, i bumped something and rolled one of the blades under a little so i bought a rebuilt prop, same pitch,same size.Got the boat in the water to try it out, noticed tach wasnt working on the way out then the high pitch alarm came on about the time i opened it up then it went off just a short distance out. I usually run 52mph (99' 90hp tracker motor)seemed alittle nose heavy but felt like it wanted to run faster but coulld'nt get over 46mph, everthing else seems to be working fine.Any ideas on what may be wrong would be appreciated.Gonna have to take the boat back to the dealer again,had another stress crack come up again on the side for the third yr.in a row.Bummer!Just want to add to this by saying Rich, your doing great job on the site,really appreciate everything you have put into it and that this is the best group of people to have to go to for help or for whatever and im proud to be just alittle part of it,there is just so much information,skill and talent here and i hope to get to meet or fish with some of you someday.May God bless this great land of ours. Thanks again

Steve ><}}}}'>

 

[Barry Loos]

I agree with Bob. With all things being equal, rebuilt props can be totally different than an out-of-the-box new one. I would bet if you tried another prop you'll find the tach is okay. Right now it is just reading the result of your current motor/prop combination.