Need help with Onan 4000

jeep2001 · 06-19-2015, 08:46 PM

I have 2007 Aspect that I bouught a few months ago. I ran the generator about every month. I started it today and it took me a few times to get it started. I forgot to prime it so maybe this is why. I ran it for 25 minutes with ac on and it ran fine. I turned it off for a few minutes and when I restarted it, it will run slow and rough for 45 seconds and then will stop. When I would try to restart it it would do the same and not run. I checked the air cleaner and spark plug and they were fine. The oil was clean and did not smell with gas. I had the lite flash 3 times and I hit the stop button and got a code 14. The code is about the governor but I think because the very low RPMs is what is setting the code. When the engine is running badly I try to open the throttle and the engine would die out. I have about 1/2 tank of gas in the motorhome. I just tried the generator about 30 min ago and it started fine and when I turned it off and try to restart it I have the same problem. The generator has 100 hours on it. Any help would be great. Thanks Mike

TonyDi · 06-19-2015, 08:49 PM

Have you tried changing the generators fuel filter?

Pullin' Chocks · 06-19-2015, 08:55 PM

We are on our third fuel pump on our 4000. Genset is 2 y/o.

Dtwallace · 06-19-2015, 09:34 PM

Sir,
I'm leaning towards the carburetor needing to be cleaned. This is an issue I've run into many times on these gasoline fueled generators.

Todays fuels (gasoline) will pick up so much moisture (hydroscopic) and hold it, your carb will gum up much faster. A good fuel stabilizer/additive will help.

The items that gum and cause the code you're experiencing are, the throttle that you moved and said the engine died out, the float valve that lets fuel into the bowl, the choke that will either stick closed or in the open position, (also cause it to run rough) and the hi and low speed jets.

It sounds to me your issue could just be a minor one that can be fixed by the spraying of carb cleaner into the intake tract (let it soak for a moment) and working the choke and throttle by hand to insure they move freely. Don't be surprised if you use the whole can.

If this does not fix the stumbling issue, your will have to to go farther and possibly remove the carb for a complete cleaning.

Be sure also you have adequate fuel and oil level to run your gen set. Some coaches have a generator fuel pickup line that does not go to the bottom on the fuel tank. This insures you won't use up all your fuel in camp.

Be sure your engine oil level is correct, all of these gen sets have a safety switch to ensure you can't run the engine with the oil level too low.

Although the last tip will have nothing to do with a rough running engine, just one more possible issue to eliminate.

Hope these tips help you, happy trails.
DTW

jeep2001 · 06-19-2015, 10:18 PM

Thanks for all the replies is there any way I can pull the line off the carb to see it it is pumping gas. I am going to put more gas in the motorhome tomorrow to see if that helps. I see that the gas filter and pump is under a black box is this an easy job to do. If the carb is clog would it run fine for 25 minutes and not run at all 5 minutes later. Thanks Mike

Arch Hoagland · 06-19-2015, 10:20 PM

Once a year I add about 6 cans of Seafoam to my gas tank just before a long trip.

While on that trip I run the Onan 5500 generator for at least an hour.

Once you get the problem cured I'd suggest adding a cleaning agent every now and then.

jeep2001 · 06-19-2015, 11:11 PM

No I have not changed the fuel filter yet. It look like there a black box that has to be removed to get to it. Would anyone know the procedure to get to the gas filter and the fuel pump? Thanks

Arch Hoagland · 06-20-2015, 12:19 AM

Quote:

Originally Posted by jeep2001

No I have not changed the fuel filter yet. It look like there a black box that has to be removed to get to it. Would anyone know the procedure to get to the gas filter and the fuel pump? Thanks

https://www.cumminsonan.com/www/pdf/...s/981-0503.pdf

jeep2001 · 06-21-2015, 12:15 PM

I picked a new fuel filter yesterday I will try to put in in on Monday.I filled the motorhome with gas hoping this would fix it but it didnt. I also seen that a bad oil level switch can cause this did anyone here of this. Can you guys give me a good starting point to begain with on this gererator. Thanks Mike

jeep2001 · 06-21-2015, 11:35 PM

Thanks for the information on the Onan manual. I am going to look at it later today. Could someone recommend a good place for parts. Thanks Mike

WBandJ · 06-22-2015, 04:12 AM

Quote:

Originally Posted by jeep2001

Thanks for all the replies is there any way I can pull the line off the carb to see it it is pumping gas.

This is the first thing I checked when our two year old Onan would not start. As Pullin' Chocks noted, the fuel pump is not very robust and subject to failure. Replacement of the filter and pump required removal and repositioning of several other items to gain access.

This thread http://www.irv2.com/forums/f54/fuel-...ml#post2276153 covers our replacement.

jeep2001 · 06-22-2015, 12:29 PM

Thanks for the threads on the fuel pump. It's been raining here but it's starting to let up. I am going to look at the problem in a few minutes.

jeep2001 · 06-22-2015, 04:44 PM

I did some testing today. I put a T-fitting on the gas line by the carb so I could hook up a fuel pressure gauge. When I primed the generator the gauge went to 3 1/2 pounds and when the generator was running 4 pounds. It started up fine and I ran the AC for 25 minutes before the generator stop running. The pressure gauge never got below 3 1/2 pounds even when the engine stopped running. I checked the carburetor bowl when it stopped running and it was full with gas.I then removed air cleaner and spray carb cleaner in the carb as I was trying to started it but that made no difference. I installed a new spark plug at this time and that didn't make a difference. I check for spark at the spark plug at this time and it seems weak. Could the ignition coil be going bad when the engine heats up or a bad oil level switch. I was thinking if the low oil level switch was bad it would have no spark at all. Is there something else I'm missing. Thanks Mike

Todd157k · 06-23-2015, 09:34 AM

Coils do go bad.. and just like that. When they heat up, they stop working. It's just not that often. Being you sprayed it, and got nothing, your problem is definitely electrical. So, either the coil is turning it off, or a sensor (heat, oil level, etc) is turning it off. Once you check your oil level, bypass the sensor (usually grounding the wire but check your sensor to be sure) and see if it runs ok. Same with any other sensors on there.

jeep2001 · 06-23-2015, 11:22 PM

I checked the spark when engine was cold and it didnt look much better than when the engine was hot. It starts fine when cold. I even shut it off when it was running good about 5 minutes to see if it would restart and it would not. I dont think the engine was running hot in that amount of time. The last few days I been getting codes 13, 14 and 15. Thanks Mike

Todd157k · 06-24-2015, 09:39 AM

some helpful hints here:

No Start/No Run Onan 4000 Microquiet H040676255 / 4KYFA26100K - SmokStak

and here:

https://www.equinerv.com/faq/2432

and here:

http://www.rvforum.net/SMF_forum/ind...?topic=16528.0

jeep2001 · 06-24-2015, 11:05 PM

Thanks for the information, I still dont understand why it starts up with no problems and runs about 30 minutes before stopping. If it was a bad slip ring or winding would it act like this? I put the gas line in a bottle today and it was pumping plenty of gas. I seen something about disconnecting the breather hose for testing would any one know what this is for. Thanks Mike