Onan 4KY Gas Genset Cuts Off Under Load

[QuiGonJohn]

I have an Onan 4KY Genset and it has started having problems. I was testing it out today, getting ready for a big trip in a few weeks. I had it running and after about 15 minutes with the A/C on, it began sputtering and cut out. I shut the A/C off, started it back up, it seemed to run OK, then I turned the A/C on and again it began sputtering and cut out.

This time I got out the book and found I had Error Code 36. I removed and checked the air filter, it was pretty clean. I removed and checked the spark plug, it looked good, I verified the gap (and scraped the surfaces a bit with the gap tool, just to clear off any residue). I put those back in and tried to clean out the Spark Arrestors, (but could not remove the clean out plugs).

Then I fired it up to test again. Started right up, within a minute or so I put the A/C on to load it, and it seemed to run fine. Then after about 8 minutes, again it began sputtering and cut out. I checked and once again had Error Code 36.

Any ideas what to try next?

I have over half a tank of gas, and we are supposed to be able to run it with more than 1/4 tank.

[hermanmullins]

How long has it been since the fuel filter was changed?

Herman

[QuiGonJohn]

Don't know, as we just bought the RV in April, but the genset has about 124 hours on it. Does the genset have it's own fuel filter or does it share the one with the chassis?

[RVerOnTheMove]

The Genset should have its own fuel filter.

[QuiGonJohn]

The only mention of it in the Generator manual is the Periodic Maintenance Schedule table. They list it as every 450 hours, (which I am way short of), and say "must be performed by qualified mechanic". I did not see it anywhere and it is not shown in any of the diagrams.

[hermanmullins]

If your generater is an Onan, The fuel filter may be accessed from a trap door in the bottom of the unit. One load of bad gas can cause a lot of problems. If you change the filter, they can be bought from Camping World or an Onan Dealer, and the unit runs like it should I would change the fuel filter on your coach at the same time. The 450 hours is just a guide. Also if your gen set is a 4KW Onan make sure your oil level is correct. What you have is a Splash Lube Engine. That means you do not have a oil pump nor a filter. The lubrication come from the rod cap dipping into the oil as it turns. If you are low on oil you may be over heating and that could be the reason for the shut down.

1) Check oil Level. If low top off and run gen set (with a load on it) and see if it still shuts down.

2) Then change to fuel filter. Small cost no matter wht.

Good Luck.

Herman

[wolfe10]

How old is the generator/coach?

It is quite possible that with that few hours, that the carburetor is clogged up with varnish. Seafoam or other product may help.

[QuiGonJohn]

It is a 2006, I gather the genset came with the RV. Would the carb issue allow it to run 5 to 15 min's fine, then start acting up?

How would I use Seafoam? Add to the fuel or are you talking remove/disassemble the carb?

[wolfe10]

http://www.seafoamsales.com/how-to-use-sea-foam-spray.html

Disassemble of the carb may not be needed-- that is the purpose of the Seafoam.

Their website is pretty descriptive in what needs to be done.

And 124 hours in 6 years means it has likely sat for long periods of time with old gasoline in it.

Is it certain that there is gunk in the carb causing the problem-- no. But it is one of the least expensive to work on and one of the most likely causes.

[hermanmullins]

Fresh gas, Fresh fuel filter and Seafoam. Sounds like a plan to me.

Herman

[QuiGonJohn]

Thanks for all the info. I will definitely pickup Seafoam, as well as another Fuel Filter, (if I can find it within this trap door). I do see an opening that has an oblong oviod metal cover, held in place with 2 allen head screws, so I am assuming it is under that. I have attached a pic of the carb, as it sits in the genset. From what I saw on the Seafoam site, I guess I need to remove the air filter and spray the seafoam in that way, (the air filter goes off to the left of the carb, in this photo).

One thing I should mention, when I was doing all this testing and troubleshooting yesterday, it was hot as blazes out, (so hot metal tools laying in the sun got to hot to handle). The side of the RV with the generator, and the generator itself, were exposed to this heat.

I did another test this morning, much cooler out. It started fine and once or twice ran rough, just at first. After about 3 minutes with no load (or minimal charging house batts), I turned on the A/C and after 10 minutes with it running, I added in the refrigerator. After 5 more minutes I shut off the A/C & fridge, let it run 2 more minutes to cool a little, then turned off the genset. All through this, except for the slight issue after initial start, it seemed to run fine.

When doing Google searches on this yesterday, I read that some people think a problem like this could be vapor lock due to excessive heat. What do you guys think, in regards to all this additional info?

Thanks again!

[jk3700]

I guess I missed what the error code 36 is?

[QuiGonJohn]

It says in my manual: Engine Stopped Fault

Corrective Actions:

1. Check and fill fuel

2. LPG (N/A)

3. Check/Secure Spark Plug Lead

4. Replace Spark Plus

5. Service Air Cleaner

6. Check for mechanical damage.

In my original post, I described the steps I took, as related to these things.

Herman, that opening I mentioned is showing in my book as access to the Oil Drain Plug. Do you think the fuel filter would be in that area, as well. That is the only trap door of any sort on the bottom of the generator. I looked around it some more and did some Google searches and it seems the fuel line goes into the genset from the left side along the bottom. There is a rubber cover there, (that the fuel filter tip sticks thru ... with the fuel line clamped on). So it seems one has to undo the clamp, pull the fuel line off, remove the rubber cover, then replace the fuel filter, then reverse the process. Problem is space is kinda tight to work there.

[hermanmullins]

John, don't hold me to this but if I remember correctly when I changed the one on my 4kw Onan I removed one of the side covers. You will have a hose clamp on the inlet side and a threaded line on the outlet.

Hope I remembered right.

Herman

[QuiGonJohn]

So I did the Sea Foam Spray Treatment on the Genset and it seems to have helped.

Would you do the same kind of spray treatment on the RV's actual engines carburetor. My thinking was, if it did so good on the Genset, it couldn't hurt to clean the engines carb good, and might slightly improve fuel mileage.

But is there any reason I should NOT do that? Something it might damage, or whatever.