Tach problem

[Bolo]

My tach on my E32-III, which has a Universal 25XP engine, has started to act very strange. Only lately (or I've only started to notice this after owned the boat for 4 years) the tach will not work after I start the engine. But after I motor out for a sail I'll look down and see that it's working. Also, when I start the engine the tach will very momentarily jump up to about 1000 RPM then drop back to zero. This will happen each time I start the engine when the tach does not work at warm up. Occasionally it will stop working after we're under way but not often.

I've checked all the connections at the tach and on the alternator and can't seem to fix the problem. But then the tach starts working again and how can you fix something thats not working?! I have not other problems with the engine or batteries.

 

[jmcpeak]

Had a similar problem.

If you follow the wiring harness from the panel to the motor you will find a white 8 pin connector (it's kind of like a trailer wiring harness, just twice as thick).

Wiggle it apart - clean it up good with fine grit sandpaper or what ever you have handy. That should do it.

If you can't find the connector, let me know. I'll try and snap a picture of it.

 

[Rocinante33]

Rust never sleeps & copper or aluminum oxide, too.

Check the ground, also. There could be some corrosion at play.

 

[Bolo]

Thanks!

Jason & Keith, Thanks for the suggestions which I'll check out as soon as I get rid of this #$%! summer cold. UGH!

 

[ted_reshetiloff]

Doubt this is the case but maybe...

I use a zantrex programmable alternator regulator. The tach feeds from it. The regulator slowly ramps up the alternator output after the engine has been running for about a minute. This is to prevent premature belt wear and to allow the engine to develop good oil pressure before putting the high load of the alternator on. If you have a programmable regulator you wont see tach readings for the first minute or so of engine running.

Probably just corrosion at the plug as suggested but also check the connection at the alternator for corrosion.