Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×


Reply
 
Thread Tools Display Modes
 
Old 12-14-2015, 11:22 PM   #1
Moderator
 
crazycal's Avatar
 
Join Date: Feb 2007
Location: NUNYA
Posts: 4,236
Year: 1995
Coachwork: Thomas
Chassis: 3800
Engine: DT408, AT545
Rated Cap: 23 500 gvw
Onan generator help.

Not sure if I should put this here or mechanical. I'll start here.

I found an Onan generator on craigslist for $75. The ad said it was listed at $275 until it developed a problem staying running. I went and picked it up. We started it and it ran for about 30 seconds before dying. It could be started again. I thought it might be bad gas and maybe gummed up carburetor. The seller said he thought it might be the governer. This is old school. Any ideas where or how to diagnose the problem?
Attached Thumbnails
a.jpg  

__________________
I'm hungry!

You Gotta Let Me Fly
crazycal is offline   Reply With Quote
Old 12-15-2015, 12:31 AM   #2
Bus Nut
 
Join Date: Aug 2015
Posts: 308
Take it to an onan service shop, use a fake name/ burner phone ($20 at walmart or free with google voice). See what it needs and if it needs more than its worth just walk away from the 75 dollar problem.
CaptainInsaneo is offline   Reply With Quote
Old 12-15-2015, 12:33 AM   #3
Moderator
 
crazycal's Avatar
 
Join Date: Feb 2007
Location: NUNYA
Posts: 4,236
Year: 1995
Coachwork: Thomas
Chassis: 3800
Engine: DT408, AT545
Rated Cap: 23 500 gvw
Quote:
Originally Posted by CaptainInsaneo View Post
Take it to an onan service shop, use a fake name/ burner phone ($20 at walmart or free with google voice). See what it needs and if it needs more than its worth just walk away from the 75 dollar problem.

That's not how I roll. There are no electronics and I want to fix this myself. It can't be that hard.
__________________
I'm hungry!

You Gotta Let Me Fly
crazycal is offline   Reply With Quote
Old 12-15-2015, 06:48 AM   #4
Site Team
 
Join Date: Jun 2014
Location: southwest lowsyana
Posts: 542
Year: 1988
Coachwork: ward
Chassis: international
Engine: dt360a
Rated Cap: 65
if it restarts within a few seconds of dying, clean entire fuel system (it needs it anyway). if it still dyes, or has to cool for awhile before restart, check the coil.

a quick check i would always do was to hold a can of wd-40 near the carb throat. when it started to wheez or die, give short burstsof wd40 to kep it running. this confirms its a fuel starvation thang.
claydbal is offline   Reply With Quote
Old 12-15-2015, 08:22 AM   #5
Skoolie
 
WoodenYouKnowIt's Avatar
 
Join Date: Dec 2015
Location: Lake Barkley
Posts: 127
Year: 1998
Coachwork: Prevost
Chassis: H3-45
Engine: Detroit DDEC III
Rated Cap: A LOT
Quote:
Originally Posted by claydbal View Post
a quick check i would always do was to hold a can of wd-40 near the carb throat. when it started to wheez or die, give short burstsof wd40 to kep it running. this confirms its a fuel starvation thang.
Yes, I agree. A can of starting fluid will work well too. This will also tell you if you have any gaskets leaking which would indicate a loss of vacuum.

Take a compression check.

I had a landscape biz for twenty years and, during that time, operated literally dozens of small engines. The very FIRST thing that we always did was simply change the spark plugs. Often the the problem was not with the plug/s but just as often it WAS. Spark plugs for small engines are notoriously poor quality but cheap to replace.

I also agree that, with no electronics, the problem would simply not be that difficult to trace.

Check to see what sort of fuel pump this engine has. Many, many small engines use a vacuum fuel pump that can develop a less than optimum diaphragm if allowed to sit for an extended time. This could also be the problem.
WoodenYouKnowIt is offline   Reply With Quote
Old 12-15-2015, 10:07 AM   #6
Bus Geek
 
Join Date: May 2014
Location: West Ohio
Posts: 3,829
Being all mechanical, It should be easy to diagnose. Claydbal hit the nail on the head with diagnosing it. You need four things for any engine to run: Fuel, air, ignition and compression. Because it will start and run initially, odds are you're looking at fuel and ignition. So do what claydbal said, I usually use carb cleaner, I stay away from starting fluid(too volatile), and test it out.

The hard part might be trying to find parts for it.

PS. How loud is it? I see one on craigslist that looks identical, but I already have a briggs powered generator. So if the onan isn't something I can run all night and not upset the neighbors, then it's no use to me. And I'm not spending 4,000 on a generator that gets used twice a year.
Booyah45828 is offline   Reply With Quote
Old 12-15-2015, 10:14 AM   #7
Moderator
 
crazycal's Avatar
 
Join Date: Feb 2007
Location: NUNYA
Posts: 4,236
Year: 1995
Coachwork: Thomas
Chassis: 3800
Engine: DT408, AT545
Rated Cap: 23 500 gvw
I will try to make a video and post it. It is a slow speed, so 1800rpm. It is definitely not a Honda EU2000 but I have heard louder. This thing weighs about 250 pounds and only rated at 2000 watts.
__________________
I'm hungry!

You Gotta Let Me Fly
crazycal is offline   Reply With Quote
Old 12-15-2015, 11:56 AM   #8
Bus Crazy
 
2kool4skool's Avatar
 
Join Date: Oct 2015
Location: Spring Valley AZ
Posts: 1,343
Year: 2000
Coachwork: Bluebird
Engine: 5.9 Cummins
Rated Cap: 2 elderly children, 1 cat
There's experts at:

Onan Generators - SmokStak
__________________
Don, Mary and Spooky the cat.
2kool4skool is offline   Reply With Quote
Old 12-15-2015, 12:07 PM   #9
Moderator
 
crazycal's Avatar
 
Join Date: Feb 2007
Location: NUNYA
Posts: 4,236
Year: 1995
Coachwork: Thomas
Chassis: 3800
Engine: DT408, AT545
Rated Cap: 23 500 gvw
Quote:
Originally Posted by 2kool4skool View Post
There's experts at:

Onan Generators - SmokStak

Waiting for my registration to get approved.
__________________
I'm hungry!

You Gotta Let Me Fly
crazycal is offline   Reply With Quote
Old 12-15-2015, 12:53 PM   #10
Bus Crazy
 
Stu & Filo. T's Avatar
 
Join Date: Sep 2013
Location: Vacaville, Ca
Posts: 1,634
Year: 1988
Coachwork: Crown / Pusher
Engine: 8.3 Cummins
Did you check fuel lines for any cracks no matter how small?? Gas these days just destroys rubber fuel lines.
Stu & Filo. T is offline   Reply With Quote
Old 12-15-2015, 03:59 PM   #11
Skoolie
 
Join Date: Mar 2010
Location: Texas
Posts: 218
Year: 1997
Coachwork: AmTran
Chassis: Genesis
Engine: DT466
Rated Cap: 84
A heads up that in recent years, WD-40 uses CO2 as its propellant to make it less burnable. They used to use butane (IIRC). Not sure how this affects the WD-40 trick, though.
Timelord is offline   Reply With Quote
Old 12-15-2015, 07:43 PM   #12
Bus Crazy
 
opus's Avatar
 
Join Date: May 2010
Location: Montana
Posts: 1,626
Year: 1995
Coachwork: Blue Bird
Chassis: All-American R/E
Engine: 8.3 Cummins
Rated Cap: 72
Take the carb apart. That is most always the problem. Doubt it has anything to do with the gov. Pretty dead simple units.

Dont lose parts or rip gaskets. Stuff is getting scarce. If you do, you'll have to improvise.

What model is it?
opus is offline   Reply With Quote
Old 12-15-2015, 08:47 PM   #13
Bus Nut
 
Alan N's Avatar
 
Join Date: Jan 2015
Location: Gonvick MN
Posts: 339
Year: 1975
Chassis: Gillig
Engine: Cat 3208t/10 speed transmission
Check out the air intake all the way from the filter to the carb.
I have a similar Onan.
Last spring it ran like yours.
Acorns in the carb throat.
__________________
Remove hence to yonder place....
Alan N is offline   Reply With Quote
Old 12-15-2015, 10:41 PM   #14
Bus Geek
 
turf's Avatar
 
Join Date: Apr 2013
Location: Colorado
Posts: 2,556
Year: 1993
Coachwork: bluebird
Engine: 5.9 Cummins, Allison AT1545
Rated Cap: 2
carb rebuild should fixit.

gas that sits in carbs, turns to shellac in carbs
__________________
.
Turfmobile Build Thread
turf is offline   Reply With Quote
Old 12-16-2015, 06:24 PM   #15
Bus Crazy
 
Join Date: Jan 2008
Location: Adirondack Mountains NY
Posts: 1,101
There are relays in under the cover behind the ammeter. When you hold the "start" switch the engine will turn over. There is a relay that responds to oil pressure that keeps power to the ignition as long as there is pressure.

I seem to recall that there is also a delay relay that ignores no oil pressure for the first 30 seconds while the pressure builds. That might be on other models, it may depend on you holding the "start" switch.

Start it with the cover off of the relay box, and see if one of the relays releases just before the engine starts to die.

It may be as simple as a plugged or bad oil pressure switch.

Now that I think about this, if you hold the "start" switch continuously, does the starter crank forever, or does the oil pressure cause the relay to release the starter motor once it is running a bit?
__________________
Someone said "Making good decisions comes from experience, experience comes from bad decisions." I say there are three kinds of people: those who learn from their mistakes, those who learn from the mistakes of others, and those who never learn.
Redbear is offline   Reply With Quote
Old 12-16-2015, 07:03 PM   #16
Moderator
 
crazycal's Avatar
 
Join Date: Feb 2007
Location: NUNYA
Posts: 4,236
Year: 1995
Coachwork: Thomas
Chassis: 3800
Engine: DT408, AT545
Rated Cap: 23 500 gvw
Quote:
Originally Posted by Redbear View Post
There are relays in under the cover behind the ammeter. When you hold the "start" switch the engine will turn over. There is a relay that responds to oil pressure that keeps power to the ignition as long as there is pressure.

I seem to recall that there is also a delay relay that ignores no oil pressure for the first 30 seconds while the pressure builds. That might be on other models, it may depend on you holding the "start" switch.

Start it with the cover off of the relay box, and see if one of the relays releases just before the engine starts to die.

It may be as simple as a plugged or bad oil pressure switch.

Now that I think about this, if you hold the "start" switch continuously, does the starter crank forever, or does the oil pressure cause the relay to release the starter motor once it is running a bit?

Interesting. It doesn't have a starter. It has an exciter starter??
__________________
I'm hungry!

You Gotta Let Me Fly
crazycal is offline   Reply With Quote
Reply

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 12:36 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2024, vBulletin Solutions, Inc.