I would clean the carb before replacing it. A friend of mine has to clean the carb on his generator every few months if he doesn't run it regularly.

 

I had this exact problem on my portable generator. Had two problems actually, but only one applies in this case.

Problem 1 was a dirty carb. I forget to run the gas out before putting the generator away. The gas in the carb bowl evaporated and left behind deposits that clogged the main jet. Wouldn't even start the next time I tried (months later), and would only sputter if I sprayed gas down the carb throat. After I tore down and cleaned the carb, it runs great. Haven't had to mess with it since.

My other problem was the oil pressure switch. My generator would start up, and then die after a few seconds. The control board uses the oil pressure switch to monitor the engine. If the pressure drops it will shut down the engine to prevent damage. Now, there is a time delay built in to the control box to ignore the oil pressure sensor for a seconds to allow the engine to start and run up to it's rated speed and get the oil pressure up. If the switch is faulty, then the control box won't know if the engine has oil pressure and will shut down the engine. Once I changed the switch, it would run normal again.

Here's a thread I started about it back in 2007. Post #8 had the troubleshooting process and my ultimate discovery: https://www.dieseltruckresource.com/...oblems-132554/

Hope this helps

 

Then I would run only non-oxy fuel in it.

My generator sits for months at a time in the back of the truck. When I need it, I can usually open the fuel valve, give it a couple of pulls, and go to work.

I run only non-oxy fuel in all my small engines, and also in the old beat up 4x4 unlicensed yard truck that sometimes sits for months without use.

 

I have the same problem with my Onan 5500. The code I get (I forget the code, might be 33) translates to, "engine stopped." (Yeah no ****). My best guess has been a bad power output board, as I know the fuel pump works, it has fresh spark plugs, a clean carburetor, etc. Just haven't had the time or money to troubleshoot it.

 

Sorry all for the late reply to your posts. I ended up stopping by the Rocky Mountain Cummins shop here in Vegas on Monday to pick up a fuel cutoff solenoid. While waiting for the parts department, I ended up talking to the service folks. The gal at the counter is a gen tech, so I explained the situation to her. She said to not change the cutoff solenoid. She said if that was a problem, then it wouldn't start at all. As others have mentioned, she said it is more than likely the carb. She suggested spraying brake clean in the carb while trying to get it to run (starter fluid can cause damage)...if it runs, it is definitely a fuel issue and since I already replaced the fuel pump and filters, the last culprit is probably the carb based on codes 36 and 37 that is thrown when it shuts down.

I brought the carb home with me, so I'm going to check the float and try to do a little cleaning and if I have time, I'll run back out to the base this weekend where the trailer is at, reinstall the carb, remove the filter, spray carb cleaner through that port, let it sit for a minute and attempt to start it. I'll basically follow this video I found on YouTube with the same generator and problem as I am having:

 

Thanks for keeping the thread updated. I still think it could be the cheaper solenoid though. But heck.....whatever it takes to get it running.

 

You probably have a code 36, not 33. Per the SM, a Fault Code 3 is interpreted as a non-assigned Fault Code 33.

Fault Code 36: GENSET Stopped without fault condition...basically what mine will throw if it doesn't run but maybe 30-60 secs. If it runs for a couple minutes, then shut down, I will get a FC 37, but I really think that happens because it is not able to get a load because it doesn't run long enough for a load to be applied.

 

Since I have the carb here with me, I'll check out the solenoid to see what it does. It would definitely be the cheaper fix, but Cummins doesn't provide anyway to troubleshoot it, other than if fuel drains from the float bowl, then it is the fuel cutoff.

But you're right, what it takes to get the darn thing running lol. I hate to throw a new solenoid on it, then it not be that and have to get a new carb anyhow

From the video I attached, surely I could get it running by doing what he did...we shall see

 

Well, still a no go. Decided to bring the trailer home this evening to work on the gen and to take the family out to ride their dirt bikes tomorrow. Removed the fuel cutoff solenoid and bowl. Their was pieces of that orange thread sealant at the bottom that comes on the end of the Onan fuel filters. Cleaned the bowl out with carb cleaner and hooked up the solenoid to a 12V battery and that worked just fine (pulls plunger down). Reinstalled the carb and sprayed lots of carb cleaner in it, primed the fuel system and started it up. Had it running for a bit, but could only keep it running by spraying shots of the Berryman B-12 carb cleaner or brake cleaner in it (both did the same thing).

Decided to see if it could possibly be the fuel, so I ran a line down to a fresh can of gas, same thing.

When it shutoff, it flashed a Fault Code 36.

So I guess I will be getting a new carb next. If that doesn't fix it, I'll throw in the towel and drop it off someplace to have it looked at.

 

Well I guess this can all be chalked up as learning a lot.

I personally wouldnt buy a carb unless I had no other choice. They're just not very complicated inside, but yet they're very expensive. So pulling it off and digging into its simplicity is the route I'd suggest before shelling out hard earned money. Whats the worst thing you could do besides having to buy another one you already planned on buying.

So if you pull it off and pay attention to what goes where and how everything is EXACTLY positioned while taking it apart, take notice of all jets and small orifices. I'm betting you'll find that either one of the jets is clogged with goop or one of the very small metering jet orifices is plugged up. Have some small gauge wire ready, some clean rags, carb cleaner, and fine steel wool, and an air compressor ready to go. I've discovered that twisty ties have the perfect size and strength wire in them for peering in carb jets.

How do I know this, well because the new ethanol fuels are so crappy that I've had to mess with log splitter carbs in the winter and lawn mower carbs in the spring. Todays fuels are just terrible and if you dont run the engine at least every few months then the fuels separate and start to leave residue on the surfaces. So I take 'em off, clean 'em up (all while keeping the settings the same), and everything is good to go again.

 

I agree with Katoom, Carbs are very simple and it is usually a plugged orifice, the only reason to buy another carb is if it's worn out or damaged and usually even a worn out one can be rebuilt. I only run premium fuel in all my small engines now because as Katoom says the fuels today are garbage. I recently found out that some fuel system cleaners when mixed out of proportion will give strange results, more is not the way to go. I would almost guarantee that you will find a plugged jet. I keep a small squirt bottle to fill with fresh gas to squirt down the throat of the carb on engines that are having problems starting, this rules out stale gas, a blocked carb or plugged air intake. Good luck. Oh. the fuel shut off solenoid can usually be heard clicking when the ign is turned on. Also the vacuum fuel pumps on some small engines can be problematic and often people go with an electric one to give reliability.

 

KATOOM/BusBoy and everyone else that gave sound guidance,

I heeded y'alls wisdom! Took it apart again this morning...removed the center jet (I think that is the main jet?) as well as a small orifice that screwed on that faces the air filter housing and both were clear. I used a piece of stranded cat5 wire and ran it through every orifice I could find. I blew air through where the altitude adjustment is at, reinstalled the carb and she fired right up after priming it. I let it run for about 10 minutes then turned the A/C on and she ran perfectly for an hour. Turned the A/C off, let it cool down for a few minutes and shut her down. We are now up at Chief Mountains letting the kids ride their dirt bikes. The generator, once again, fired right up.

Thanks for the guidance and encouraging me not to buy a new carb. You read things online and people make it sound like these carbs can't be massaged when things go south. I'll now be sure to keep fuel out of the carb when in storage and go out once a month to the storage yard and exercise it with a load.

Can't thank y'all enough!

 

Good to hear it's finally cured... I recently bought a new 3500w inverter genny, took it home and put the very best synthetic oil into it, premium gas then yanked on it a gazillion times without a single burp. I was going to take it apart and make it work then thought.. why?? I drained the fuel, left the oil and returned it, if it won't work brand new then it's probably going to be a pain it's whole life.

 

Well thats great news.....!

 

Too much junk floods the market nowadays. So I don't blame ya for returning it. We bought a pressure washer from Sam's Club a few years ago and it hardly ever runs right...been like that since day one. Now, it only runs with the choke pulled...I guess now that I'm schooled in tearing apart carbs, I might as well tear that one apart to see what's going on inside of it. Probably needs a little TLC as well.

My grandfather gave me one of those self-propelled lawn-mowers he bought a few years ago, he said he only used it once...maybe twice, then parked it behind the shed because it wouldn't run right. Brought it home as a project for my son to work on, maybe we both can learn something from it.