Reply
 
Thread Tools Search this Thread Display Modes
 
Old 11-03-2018, 11:40 AM   #1
Veteran Member
 
City: Deale
Country: MD
Vessel Name: Vanda
Vessel Model: 1982 Mainship MK1
Join Date: Dec 2012
Posts: 48
Generator Discharge Troubleshooting

My 82 Mainship MKI has its original OEM Onan MDJA 3KW genset. It starts and runs fine. The boat has 3 FLA batteries on a NOCO Gen3 charger. The batteries normally show 13.4-14V with the battery charger on, and the main panel shows 120V on either shorepower or generator power. I periodically exercise the generator under medium load for 30 minutes.

I ran the usual generator exercise routine about 10 days ago, with the reverse cycle a/c and battery charger on. I noticed battery voltage measured at the helm dropped to about 12.8V and the voltmeter on the main panel dropped to about 108V. I checked the ammeter on the generator and it was showing -2 Amp.

I started the generator again yesterday and with no load it showed 0 Amp output. I turned the a/c on, and the output immediately dropped to -2 Amp. I shut the gen down and aborted the exercise routine. I switched back to shorepower and everything returned to normal.

I have very little experience with electricity, and have only a digital multimeter. I don't know how to safely begin troubleshooting the issue. Any and all guidance will be greatly appreciated.
__________________
Advertisement

lucky day is offline   Reply With Quote
Old 11-03-2018, 04:23 PM   #2
Guru
 
Alaskan Sea-Duction's Avatar
 
City: Inside Passage Summer/Columbia River Winter
Country: USA
Vessel Name: Alaskan Sea-Duction
Vessel Model: 1988 M/Y Camargue YachtFisher
Join Date: Jul 2012
Posts: 4,744
My advise is to hire a generator tech to fix your issue.

With you very limited to non-existent experience around electricity, you could get hurt or worse kill yourself.....
__________________

Alaskan Sea-Duction is offline   Reply With Quote
Old 11-03-2018, 04:44 PM   #3
Guru
 
LaBomba's Avatar
 
City: Beaverton, Ontario
Country: Canada
Vessel Name: Looking Glass
Vessel Model: Carver 370 Voyager
Join Date: Nov 2012
Posts: 1,145
Quote:
Originally Posted by Alaskan Sea-Duction View Post
My advise is to hire a generator tech to fix your issue.

With you very limited to non-existent experience around electricity, you could get hurt or worse kill yourself.....
I think this is sound advise. The only thing I might try is to check the fuses on the generator. I have two on mine on the control panel. Short of that call someone. It may be a simple solution but some training is required to find it safely.
__________________
Allan
LaBomba is offline   Reply With Quote
Old 11-03-2018, 05:00 PM   #4
Guru
 
psneeld's Avatar
 
City: AICW
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 19,834
Do you have a manual with any troubleshooting in it?

If not, can you find one on the net?

Some forum sites have libraries to download manuals, there is manufacturer or dealer websites, there is boatdiesel.com to ask questions (pay site but usually worth it)

I do not consider simple troubleshooting by a manual to necessarily be life threatening....
psneeld is online now   Reply With Quote
Old 11-04-2018, 06:39 AM   #5
Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 5,307
Those old MDJ series had external governor springs that get some corrosion on them and lose tension. If reading 108Vac under load, it could be as simple as low rpm. Get a meter that has Hz setting (frequency) or phototach the engine. Could be a simple adjustment. Should be 1800rpm under normal heavy load, about 1850 under no load.
Ski in NC is offline   Reply With Quote
Old 11-04-2018, 08:02 AM   #6
Veteran Member
 
City: Deale
Country: MD
Vessel Name: Vanda
Vessel Model: 1982 Mainship MK1
Join Date: Dec 2012
Posts: 48
Thanks for all the responses. I can't argue with the warnings about electrical troubleshooting hazards. I've found some online links to a repair manual - was reluctant to subscribe to libraries like scribd.com because they require I provide credit card information (I've become averse to providing that info online). I'll look into getting a qualified tech to check the electrical side of the issue.
I'm also going to see about checking the actual rpm. Thanks again for all the responses.
lucky day is offline   Reply With Quote
Old 11-04-2018, 11:07 AM   #7
Guru
 
Alaskan Sea-Duction's Avatar
 
City: Inside Passage Summer/Columbia River Winter
Country: USA
Vessel Name: Alaskan Sea-Duction
Vessel Model: 1988 M/Y Camargue YachtFisher
Join Date: Jul 2012
Posts: 4,744
Please make sure you post your solution to not only close this thread out, but so the rest of us what your solution was. We also like pictures too.....Good Luck.
Alaskan Sea-Duction is offline   Reply With Quote
Old 11-06-2018, 02:08 PM   #8
Veteran Member
 
City: Deale
Country: MD
Vessel Name: Vanda
Vessel Model: 1982 Mainship MK1
Join Date: Dec 2012
Posts: 48
Iíve got a generator tech coming out to the boat next week. Iíll circle back and update this thread when l know more.
lucky day is offline   Reply With Quote
Old 11-06-2018, 07:11 PM   #9
Guru
 
foggysail's Avatar
 
City: Ashland, MA
Country: United States
Vessel Model: 1990 Silverton 40 aftcabin
Join Date: Jul 2016
Posts: 1,079
Quote:
Originally Posted by Ski in NC View Post
Those old MDJ series had external governor springs that get some corrosion on them and lose tension. If reading 108Vac under load, it could be as simple as low rpm. Get a meter that has Hz setting (frequency) or phototach the engine. Could be a simple adjustment. Should be 1800rpm under normal heavy load, about 1850 under no load.
My Kohler sometimes has trouble with lack of lubrication on the governor external connections. Spraying the control rod ends with a lub along with manually working the control rod back and forth while doing so might solve the OP’s headache. That maneuver is far less expensive than a genny tech who may approach the problem using a similar approach.

Do this of course with the genny not running
foggysail is offline   Reply With Quote
Old 11-16-2018, 08:12 PM   #10
Veteran Member
 
City: Deale
Country: MD
Vessel Name: Vanda
Vessel Model: 1982 Mainship MK1
Join Date: Dec 2012
Posts: 48
Generator output back to normal. Mechanic needed about five minutes to confirm that the engine speed had dropped. He reset the governed speed and the generator went back to charging properly at normal 110v. I will be able to adjust the engine speed myself if needed in the future.
__________________

lucky day is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 07:41 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012
×