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 > Help! Onan 4K generator refuses to start and stay on

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wopachop

Who run bartertown

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Posted: 01/17/21 01:32pm Link  |  Quote  |  Print  |  Notify Moderator

I wonder if you could:
1. Measure and monitor voltage to the solenoid as you press and release the start button.

2. Use a battery and alligator clips to give the solenoid 12v directly.

I always recommend using an empty water bottle and short piece of fuel line to gravity feed fresh gas directly to the carb. This eliminates fuel pump, fuel filters, fuel line, old gasoline.

Also allows you to feed a very strong mixture of carb cleaner into the carb if you suspect old gas has gummed up the jets. I have fixed clogged up Onan carbs many times using that method. It's not ideal. But it's quick and easy and cheap.

bobndot

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Posted: 01/17/21 02:09pm Link  |  Quote  |  Print  |  Notify Moderator

wopachop, I remember my dad using white gas for our camp stove and its shelf life was great.
Doing what you mentioned using Coleman fuel would probably work for storing a generator during the non-use months due its long shelf life. You would not need to stabilize it. Getting that fuel into the and thru the carb and lines, I think would be good for a very long time. Others in the rv crowd talk about doing that.

wopachop

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Posted: 01/17/21 04:47pm Link  |  Quote  |  Print  |  Notify Moderator

I think many RV people would benefit knowing you can easily drain the carb. Look for a little screw on the float bowl.

Dutch_12078

Winters south, summers north

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Posted: 01/17/21 04:56pm Link  |  Quote  |  Print  |  Notify Moderator

Kennyg wrote:

Dutch_12078 wrote:

Does the generator keep running if you hold down the start switch? If it does, that indicates that it's not putting out enough voltage to the control board to lock in the run cycle. It could be a faulty voltage regulator ($$$), or it could be dirty slip rings. Holding the start button down for a minute or two may clean the rings enough to keep it running. Worth a try anyway...


No. will run ,but as soon as I release button, the engine stops.


Does it keep running as long as you hold the button down? Even for a minute or longer? If it does, it's not an engine problem, it's an electrical problem...


Dutch
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JaxDad

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Posted: 01/17/21 06:52pm Link  |  Quote  |  Print  |  Notify Moderator

Dutch_12078 wrote:

Kennyg wrote:

Dutch_12078 wrote:

Does the generator keep running if you hold down the start switch? If it does, that indicates that it's not putting out enough voltage to the control board to lock in the run cycle. It could be a faulty voltage regulator ($$$), or it could be dirty slip rings. Holding the start button down for a minute or two may clean the rings enough to keep it running. Worth a try anyway...


No. will run ,but as soon as I release button, the engine stops.


Does it keep running as long as you hold the button down? Even for a minute or longer? If it does, it's not an engine problem, it's an electrical problem...


Indeed! Older 4K units employed a very rudimentary ’safety’ system since they operated on a ‘power in / power out’ basis’. 12 volts = 120 volts out. The problem is that the genny would start on 8 or 9 volts, but 80 or 90 volts out would let release the magic smoke from things. The simple solution was a voltage sensor, much less than 12 volts meant the engine shut off. This of course is bypassed as long as you hold the start button.

Even a nothing booster pack will keep it up long enough for the battery to recover or charging to kick in.

On a few occasions I’ve stood holding the button for a few minutes.

ron.dittmer

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Posted: 01/18/21 07:02am Link  |  Quote  |  Print  |  Notify Moderator

bobndot wrote:

I remember my dad using white gas for our camp stove and its shelf life was great.
"Great" is an understatement.

My parents had old Colman fuel laying around as did my siblings. They knew we camped with a camp stove (until 2007) and gave us their old fuel. After we bought our motorhome, we had no need for that fuel. Still I kept it for years longer just in-case, and I still have one gallon today. After all those years it still remains clear as water and smells like new so I put most of it to good use in my car's fuel tank.

White gas used in camp stoves and lanterns is unleaded fuel without additives including cleaners and pollution retardants. It is as pure of an automobile fuel as you can buy, though I wouldn't recommend driving around in tank fulls of it.


2007 Phoenix Cruiser model 2350, with 2006 Jeep Liberty in-tow


klutchdust

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Posted: 01/18/21 09:25am Link  |  Quote  |  Print  |  Notify Moderator

Having been around diesel and gas engines for a lifetime I know this :

" as it starts to die on you, spray a little starting fluid in the carb to keep it running
- keep doing it until you are tired of doing so"

This in my opinion is a terrible idea, to keep an engine running on starting fluid and here's why.

Do you notice that the engine chatters, clacks and everything else while using starting fluid/ether? Starting fluid puts engines under stress, it strips the cylinders of lubrication. Sure you can spray a little if you like, it's your engine however I have not purchased or used any in my engines ever since I saw a mechanic use it, walk away then another mechanic came along and not knowing ether was sprayed - hit the glow plug button on the diesel tractor and the explosion removed the head gaskets from the block.

klutchdust

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Posted: 01/18/21 09:49am Link  |  Quote  |  Print  |  Notify Moderator

klutchdust wrote:

Having been around diesel and gas engines for a lifetime I know this :

" as it starts to die on you, spray a little starting fluid in the carb to keep it running
- keep doing it until you are tired of doing so"

This in my opinion is a terrible idea, to keep an engine running on starting fluid and here's why.

Do you notice that the engine chatters, clacks and everything else while using starting fluid/ether? Starting fluid puts engines under stress, it strips the cylinders of lubrication. Sure you can spray a little if you like, it's your engine however I have not purchased or used any in my engines ever since I saw a mechanic use it, walk away then another mechanic came along and not knowing ether was sprayed - hit the glow plug button on the diesel tractor and the explosion removed the head gaskets from the block.


Also, I am very disappointed in Sta-bil fuel additive. I have used it and still have had issues with my small engines, the ones I cannot run out of fuel before storing. Now, a product called "mechanic in a bottle" used it, it works, I recommend it to friends with no mechanical ability for their mowers etc.
so I am not asked to do a carb rebuild .....[emoticon]

Grit dog

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Posted: 01/18/21 11:06am Link  |  Quote  |  Print  |  Notify Moderator

Sorry, off the OPs topic, but I wouldn’t un-recommend Stabil or any of the other gas stabilizers.
Another suggestion that works well for stabilizing or using small amounts of fuel in engines without catalyst emissions and 02 sensors is 100LL. It’s not much more $ than non ethanol premium and it does not need to be treated or drained for about 2 years.
It’s more highly refined than automobile fuel.
OP issue sounds like a voltage or sensor issue. I do not have any direct experience w Onanistic but the suggestions sound right.


"Yes Sir, Oct 10 1888, Those poor school children froze to death in their tracks. They did not even find them until Spring. Especially hard hit were the ones who had to trek uphill to school both ways, with no shoes." -Bert A.

KMLsquared

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Posted: 01/19/21 08:25am Link  |  Quote  |  Print  |  Notify Moderator

That fuel solenoid will stick closed not allowing fuel to enter the main jet. The reason it runs briefly is because the automatic choke is on enrichening the fuel air mixture, compensating for the lack of fuel going thru the main jet. Any water in the float bowl sits on the bottom and in that solenoid causing corrosion in a short time. I just fixed an Onan with the same issue.


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