Community Forums

Buzzsaw · 08-25-2019, 09:58 PM

It was gas cruded up carb used Berryman spray in carb to clean.

bigjon42 · 08-26-2019, 11:06 AM

No carburetor, diesel generator, new fan belt, full fuel tank. Have tried everything, oil level full, On to Cummins Thursday. Jon

Jchemie · 08-26-2019, 11:43 AM

I’ve got a 5.5k onan diesel genset, water cooled. When replacing the belts during PM (preventive maint.), my parts guy suggested I replace the coolant temp switch. He has worked on these before units and said the factory temp switch tends to malfunction and shuts down the unit. Cheap, around $20, pain to get to if your unit doesn’t slide out (mine doesn’t). I know this isn’t in code 27, but while you are in there it’s a cheap upgrade that’ll save you headaches later. If you add a load to the genset it will raise the temp slightly, possibly making it shut down. Just a thought.

Bytesponge · 08-26-2019, 02:47 PM

jchemie; runs fine with no load.

shootist · 08-26-2019, 07:24 PM

My 7500w onan did the same thing, but then would not start at all. I think shutting it off under load caused it. I disconnected the 12volt power lead for 20 minutes to clear and reset the electronics in the gen. Been working fine since.

Loren B. · 08-26-2019, 08:22 PM

Quote:

Originally Posted by shootist

I disconnected the 12volt power lead for 20 minutes to clear and reset the electronics in the gen. Been working fine since.

This is an excellent idea. Anything with a computer in it may respond to a hard reset.

Good luck.

James Storm · 08-27-2019, 08:25 AM

It sounds like you have a power output problem
With your generator. If you can disconnect wires from transfer switch and check voltage across line and check for 60 hertz. If you can then hook up a temporary line and test on something outside of your rig. This can be dangerous and scary. If you haven’t done this type of work before then best left to the professional. Stormy

Loren B. · 08-27-2019, 10:17 AM

Quote:

Originally Posted by James Storm

It sounds like you have a power output problem
Stormy

I think that Stormy may also be onto something here.

A while back I had a problem with my 4000 watt Onan shutting off on its own. I couldn't find the problem and finally delivered the trailer to Onan/Cummins for repair. The mechanic found that the generator rotor was slipping on its shaft, causing faulty power.

He told me that if the generator does not sense proper power output it will shut the engine off. That's what mine was doing.

If you can disconnect everything from the generator output and test the generator alone, you may find a similar problem.

Good luck.

bigjon42 · 08-27-2019, 10:51 PM

Stormy you are on to something. One of my Nabors is a retired electrician, so I called him. He said talk to my son who is visiting and is an electrical engineer.
How did I get so lucky. He came over and tested all connections with a meter, ran some tests, determined that I have a direct short between my transfer switch and my main panel in the motorhome. I have ordered a 30 ft 50amp rv cord (6/3) and I am going to cut it and run a connection OUTSIDE the motorhome from the transfer switch thru the bedroom window to the main panel. Sounds scary, but the electricians son will help/supervise. At least the generator is O.K. !! If the test is successful, then the hard part will be running the cable from transfer switch, hidden, to the main panel in the bedroom. Underside of the coach is sealed, so I have no good idea on how I am going to do that. More later after the external test. As an aside, Cummins was and is convinced that it was NOT the generator. They were right. Bigjon.

dogwhisper · 08-28-2019, 12:58 AM

Check the little black box it’s usually under the bed . The micro board vibrates loose at least that sound exactly like what happen to mine one time . I wish I cold remember what it’s called. Pushed it back down it snapped ito place and it started working

dogwhisper · 08-28-2019, 01:12 AM

Check inside the little black box usually under the bed . Take the top off and make sure the circuit board has not vibrated loose . It’s part of the controller for the transfer switch. Wish I could remember the name it happen to me in a 2004 science cruiser. Took the top off pushed it back down in place and fixed

twinboat · 08-28-2019, 04:05 AM

So, in all of this time, you haven't plugged the shore power cord in to see if that works ?

If the cable between the a transfer switch and main breaker is shorted, the shore power breaker would trip as soon as it was plugged in.

bigjon42 · 08-28-2019, 12:04 PM

Yes, twinboat, I have tested the shore power. Did not trip breaker. That said, I have a 30amp shore plug at my house. somehow the 50amp to 30 amp adapter allowed the short on ONE leg to not be a problem. Electrical engineer was at first stumped, but eventually understood why this could happen. Beyond my level of electrical knowledge. He never did fully understand why the short on one leg would cause the power transfer switch relays to 'chatter' as gen quit. Never heard of a short in the main power loom from transfer switch to the main interior panel, all breakers 'off'. Tested and found the short exists on both end of the loom, as it should. But where ?? Bigjon.

twinboat · 08-28-2019, 01:44 PM

Its possable that you have a L1 to L2 short. Using 30 amp service sends the same 120 volts down both legs. No short.

If your generator is a 120/240 volt unit, the L1 to L2 short would rear its ugly head.

The same would happen if you plugged into 50 shore power. 50 amp shore power is 120/240 volt service. L1 and L2 touching would cause a direct 240 volt short.

Is the short between the red and black conductors ?

Still think it should trip the breakers but who knows.