Tach trouble

[ctangler]

I have a Tracker bass boat with a 1993 40 hp Mercury serial# 0G083026 model# 1-040312PT.

What can you folks tell me about a bouncing tach needle ? It will seem to work ok some times and then suddenly it goes bonkers and bounces between 2 and 5k rpm. The gauges are less than a year old and are tight and dry...no apparent damage anywhere. I looked at the wiring to the back of the gauges and it all seems tight and no visable corrosion.

I believe this is the tach in question -

http://www.overtons.com/modperl/pro...hometer_7000_rpm&aID=101A&merchID=1009&r=view

Thanks for any help you can offer.

Ed

 

[Chris1956]

Re: Tach trouble

I would think it is a connection issue. One or more of the three wires may make intermittent contact, somewhere in the wiring harness. Run some dedicated test wiring from the tach to the battery, and voltage regulator/rectifier, until the problem is fixed. Now you have isolated it to the bad wire.

 

[jtexas]

Re: Tach trouble

See the Engine FAQ forum for a couple threads on static testing of rectifiers, yours may be on the verge of going out.