Return to the home page...

Go Back   Moyer Marine Atomic 4 Community - Home of the Afourians > Discussion Topics > Troubleshooting

Reply
 
Thread Tools Display Modes
  #26   IP: 206.125.176.3
Old 12-31-2009, 12:21 PM
sastanley's Avatar
sastanley sastanley is offline
Afourian MVP
 
Join Date: Sep 2008
Location: Solomons, MD
Posts: 7,016
Thanks: 1,134
Thanked 600 Times in 442 Posts
Quote:
Originally Posted by roadnsky View Post

Again, the DC experts could certainly give us better explanations...
I think you just did Jerry...nice work!
__________________
-Shawn
"Holiday" - '89 Alura 35 #109
"Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!)
http://www.moyermarine.com/forums/signaturepics/sigpic3231_6.gif
Reply With Quote
  #27   IP: 142.68.244.115
Old 12-31-2009, 09:54 PM
rigspelt's Avatar
rigspelt rigspelt is offline
Afourian MVP
 
Join Date: May 2008
Posts: 1,187
Thanks: 0
Thanked 19 Times in 17 Posts
Quote:
Originally Posted by roadnsky View Post
Again, the DC experts could certainly give us better explanations...
I'm no expert, but when I rewired the boat last year I got rid of that ammeter in the cockpit ignition panel, eliminated that long alternator output wire, and replaced it with a very short cable to the starter solenoid and thence (big word alert) to the positive terminal on the engine start battery. http://www.moyermarine.com/forums/showthread.php?t=2727

So Jerry, I think you found the same kind of problem I had with that failing slave starter solenoid: bad connections in old circuits. Good work.
__________________
1974 C&C 27
Reply With Quote
  #28   IP: 142.68.253.106
Old 05-05-2010, 06:05 AM
rigspelt's Avatar
rigspelt rigspelt is offline
Afourian MVP
 
Join Date: May 2008
Posts: 1,187
Thanks: 0
Thanked 19 Times in 17 Posts
On re-reading this post, I've been pondering principles for this pesky jumpy tach thing. These are musings from an amateur boater who has lived through 3 used boats, not a professional marine engineer. I've only experienced it once on our first boat, but it was a nightmare. You can imagine my relief when I first fired up the engine after the big refit on this third boat and saw a nice, steady tach needle.

1. Draw complete schematics of a boat's wiring. Start with one based on the batteries and charging system (the heart of the system), and then branch out to include sub-schematics for the engine, ignition panel and house wiring. Those drawings take time to make, but they are essential for troubleshooting wiring. Take advantage of a rainy dockside day to work on the schematics with nice music going in the background. Put on work clothes, then get down and crawl into every nook and cranny, wearing glasses with little LED lights on the frames (but don't let anyone see you wearing them). Along the way, I suspect most owners of old boats discover wires, connections and parts that need updating.

2. Revising old wiring is a time-consuming but very worthy project on an older boat. Shorter and simpler appeals to me, but within sound marine electrical practices. Getting professional advice for best practices in marine electronics is not easy for average boaters.

3. A jumpy tach in an older boat can mean a mechanically faulty electrical connection in either a component or a wire. If in a component, then the easy way to identify it is to swap in a new component. Start with the cheapest ones , and the ones most likely from the schematics to be able to make the tach jumpy. Tachs are expensive, so just clean their terminals and check the cylinder number setting first, unless someone can loan you a reliable tach to swap in as a check. From the few stories I've heard, tachs can be the problem, but usually aren't.

4. The old-fashioned design for alternator wiring on our 70's vintage sailboats apparently was to run a long output wire from the alternator aft to an ammeter in the cockpit, and from there double-back forward to all other systems that draw from the alternator, including recharging the batteries. While that worked for decades in many boats when loads were lower, I get the sense that the modern style is to make the alternator output cable as short as possible, and then draw current for subsystems like the engine, ignition panel and house selectively in dedicated fused circuits. The modern approach seems to reduce opportunities for problems like the one described in this thread by eliminating the ammeter aft and replacing it with a voltmeter, and then running the alternator output directly to the battery via the starter solenoid. Electricity does not seem to like long runs, or at least it is harder to keep electricity flowing cleanly over long distances.

These are just early morning recreational musings of a hobbyist over coffee. Your mileage will vary.
__________________
1974 C&C 27
Reply With Quote
Reply

Tags
atomic 4, jumpy readings, tachometer

Thread Tools
Display Modes

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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Tachometer wiring smithla Troubleshooting 19 09-26-2011 06:37 PM
Tachometer - will it work with points? sastanley Electrical 7 10-12-2009 04:23 PM
Motor random jumpy stuttering, rough and stalling check your electronic ignition. riphonda Troubleshooting 8 07-16-2009 08:44 PM
Tachometer pegged...defective? skhorleb Troubleshooting 2 07-09-2007 05:57 PM
Tachometer needed? bputney General Interest 5 05-11-2006 06:52 AM


All times are GMT -4. The time now is 09:56 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.


Universal® is a registered trademark of Westerbeke Corporation

Copyright © 2004-2024 Moyer Marine Inc.

All Rights Reserved