Cruisers Forum

Join CruisersForum Today

Thread Tools Rate Thread Display Modes
Old 14-07-2008, 11:01   #1
Registered User

Join Date: Jul 2008
Posts: 1
Yanmar with funny Tachometer


I have a Yanmar 3JH3E circa 2000. My Tachometer seems to work (as far as I can tell) up to about 1800 RPM, then as the engine RPM increases beyond that the tach starts going down !? I have checked the alternator belt and it seems good (only 364 hrs on engine, charging works fine) and replaced the connectors on the sending unit. (I measure .75 Volts there). Have not scoped it yet. What could be wrong ?

45Sticks is offline   Reply With Quote
Old 14-07-2008, 18:41   #2
Senior Cruiser
S/V Antares's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: Annapolis, Bahamas
Boat: 1983 Gulfstar 36
Posts: 1,240
Images: 1
45Sticks, Yanmar has used a magnetic pickup on its small diesels for many years. This sensor is usually found on the top of the flywheel housing. It accually counts the teeth flywheel. about 127 teeth on most Yanmars. Some pickups are adjustable but I believe yours is fixed. They are magnetic and sometimes get bits of metal shaving and debris on them. You should get more voltage as the rpm rises. The signal is a modified square wave and you might try setting your meter to AC or frequency. This should help determine sensor or tach issue.
Will & Muffin
Lucy the dog

"Yes, well.. perhaps some more wine" (Julia Child)
S/V Antares is offline   Reply With Quote


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Really funny Alan Wheeler Off Topic Forum 15 16-02-2008 00:26
Tachometer connection ScratchBC Engines and Propulsion Systems 4 21-05-2006 17:50
A funny. :) ssullivan General Sailing Forum 1 06-01-2006 15:26
Tachometer Calibration GordMay Engines and Propulsion Systems 5 20-04-2005 22:56
Tachometer 1sailaway Engines and Propulsion Systems 9 11-11-2004 15:59

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2015 Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 12:28.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.