ONAN 5500 shut down randomly, you will not believe the fix

Yessir! I've mentioned it before. Same with mine. I would always fill to the full and nope. Brought it down and worked like a charm.

 
I did not belive it, i was about to change the fuel pump and the carb in the desert,  I can not believe i followed the Onan Directions and had a oil overfill issue,  the Dipstick is kind of a joke on this gen set,   now i fill it like the Vid and look at the threads on the fill. 

 
When Onan used their own opposed twins they were stone axe simple and reliable. These V Twins started life as Fuji/Robin/Subaru engines, and were mostly horizontal shaft applications. They are a good engine, but it seems something got lost in the translation. When Subaru exited the small engine business, I am not sure if Onan(Cummins) bought the tooling, or if it got farmed out to someone else.

I always ran mine below the full mark, but mine had a dislike for the 15W40 oil. On 5W40 T6 no issues.

 
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Seen this happen to a friend of mine, I removed a quart of oil and it now runs fine.

 
Mine still shuts off,  

going to do a oil change but it will run for 2, 3, 4 days, then shut off, start right back up, then shut off again, wait a full day or two and then runs fine,  UHHH

 
J Alper said:
Mine still shuts off,  

going to do a oil change but it will run for 2, 3, 4 days, then shut off, start right back up, then shut off again, wait a full day or two and then runs fine,  UHHH
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Crap! Don't say that, I just put one of those China carbs on 😭

 
My last Toy Hauler with an Onan would shut down randomly as well.  Sometimes it would be minutes and sometimes it would be hours of running before the shutdown.  Oil and fuel were good so my theory was that the On/Off switch on the Genset was vibrating to Off causing the shutdown.  However, I never caught it doing that and sold the Toy Hauler.  My Moho with the same Onan doesn't shut down randomly.  Problem solved. 

 
I just went through this on a two year old toyhauler and replaced the pump twice, drained oil out and fiddled with it for a couple trips.  
 

I finally pulled the carb and went to cleaning it.  I found red fine pencil eraser looking stuff in the pilot jet.  Cleaned it all out and she runs like a champ now.  
 

This video helped me alot






IMG_4773.jpeg

 
Chingon619 said:
Crap! Don't say that, I just put one of those China carbs on 😭
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The China carp never was great worked for a emergency but that was it, The Amazon Onan was a Fake for $350

This is a $500 Onan Carb, From Onan,  Starts perfect, idles good,  will clean it out just in case,  might have the float getting stuck,

Next time it happens, i need to turn the drains to see if anything comes out,  The Filter is full when it happens and the pump is still making its noise, so dont think it is a pump, but have 2 spares just in case, 

I see so many EFI 5500 for sale now for 3K   really thinking that rout next year,  

 
On 3/2/2024 at 8:23 AM, megadesertdiesel said:

I just went through this on a two year old toyhauler and replaced the pump twice, drained oil out and fiddled with it for a couple trips.  
 

I finally pulled the carb and went to cleaning it.  I found red fine pencil eraser looking stuff in the pilot jet.  Cleaned it all out and she runs like a champ now.  
 

This video helped me alot

Click to expand...
FWIW, that looks like RTV to me.  I found a bunch of that in carb bowls of an old carb & it was coming from the PO using it to seal up a fitting on the gas tank.  the filter was about plugged up, but it was soo bad some was getting through the filter into the carb.  Mind you this was on a car, but that is exactly what the bowl looked like.

 
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