Yanmar 3GM30 rev counter temperamental

[fredrussell]

Sometimes it works, more often it doesn’t. Obviously a new one is going to be surreally expensive, and I can happily live without it, but are there any checks I can do to find the cause?

 

[fredrussell]

Did a YBW search on this and found nothing. Have since done a google search and it came up with loads of threads on here re this subject, so ignore this one folks and I’ll work through all the suggestions on aforementioned threads.

Why is the forum search function so awful, by the way?

 

[vyv_cox]

Intermittent faults are notoriously difficult to trace but I would start with checking all wiring and connections.

 

[Old Bumbulum]

http://www.ybw.com/forums/showthrea...er-sensing-from-alternator-how-does-this-work

 

[pvb]

Why is the forum search function so awful, by the way?

Like a lot of this site, it's badly programmed by people who presumably never have to use it. If you want to search the forums, do it via Google by prefacing your search term with site:ybw.com/forums

 

[earlybird]

The usual sensor on GM engines is an inductive type located on the top of the bellhousing. It screws into a tapped hole. You could start your wiring check there.
Also, the sensor counts starter ring-gear teeth and the gap between the teeth and the sensor is fairly critical, slightly too big and the tacho stops working. Can't remember for certain, but the workshop manual might have details to check.

 

[ianfr]

If the sensor is the same as the one fitted to the Yanmar 3JH30A (probable) I had the same problem. The sensor on the bell housing has 2 push fit crimp connectors (automotive type) . The wire ends from the loom were corroded and stripping back to good copper then extending the leads back to new clean crimps has resolved my issue, I spent a little time with emery cloth on the actual sensor connections, and a wipe down with vaseline to keep them dry. Has worked faultlessly since.

Ian

 

[Old Bumbulum]

There are no end of after-market rev counters available for almost nuppence, some of which could no doubt be incorporated into your Yanmar panel.
It isn't rocket science!