We have a 2003 Adventurer 35u with an Onan Marquis Gold 5500 generator. We have recently changed the oil and filter. We have changed the plugs, adjusted the valves and installed a new fuel pump and fuel filter. We also installed a new carburetor. When we run the generator it runs fine until we run the AC. We have central AC in the coach. When we turn on the AC, it will run fine, however, every few minutes it bogs down a bit but does not cut off. When it bogs down, the lights will dim and the AC will slow down but it only lasts a couple of seconds then it runs fine again for a few minutes and then does it again. Is this normal due to the load? Is there something I can do to eliminate this stuttering? Thanks in advance for any assistance.
I am experiencing this same thing on my Onan 4000. I was running my AC and was getting the same bog down. I ran a hertz test and noticed I was a 57 and 58 under load. I was at 60 not under load.
I am thinking maybe I am supposed to be at 62 or 63 when I am not under load and 60 at load. Can anyone confirm if this is why I am bogging down?
Before I adjust the linkage arms and rev up RPMs, I did some much needed maintenance for the year.
This week:
I just put in a new starter (mine was struggling), new carb, new air filter, new fuel pump, new fuel filter, new solenoid, new spark plug, oil change, and an inline fuel filter.
You said you put a new carb on the generator. We have had multiple reports of Onan OEM carbs not being available and folks buying "compatible" carbs online via Amazon, eBay or other places.
The unanimous report is that the non-Onan carbs are lousy and don't work right.
One recent poster said he took the old original carb and the replacement carb and swapped parts back and forth about 50% OEM carb and 50% replacement carb and got that to work. I don't remember what parts were swapped.
I'm not saying this is your issue, just letting you know that many others have reported very poor running with replacement non-Onan carbs.
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2017 Winnebago Adventurer 37F
2016 Lincoln MKX Toad
Thanks for the info, it is a non oem carb but it seems to be running well otherwise. There is something else I noticed. When I watch my load meter, the amp load is about 14 amps. When it bogs down, it jumps to 53 amps for a second and then returns to 14 and runs fine until it cycles through again.
I may try to hunt down an OEM carb and try that as well.
Without knowing your make/model A/C unit, perhaps the compressor/motor unit is the problem. Try measuring amp-draw of the A/C unit with a clamp-on meter, or a Kill-A-Watt meter for a while and observe results.
P.S. This might involve sitting in a chair with a cold beverage in hand while watching the meter.
__________________ 2000 Winnebago Ultimate Freedom USQ40JD, ISC 8.3 Cummins 350, Spartan MM Chassis. USA 1SG, retired;PPA,Good Sam Life member,FMCA. "We the people are the rightful masters of both the Congress and the Courts - not to overthrow the Constitution but to overthrow men who pervert the Constitution." Abraham Lincoln
If your generator is bogging down only when the air conditioner is starting it could be because of the high amp draw. Research RVsoft start . It is a device that you install on your air conditioner . It allows the compressor to start at a lower current draw. There are other manufacturers of similiar devices. I installed the RVsoftstart on our 2014 Navion and it made a noticeable difference.
If your generator is bogging down only when the air conditioner is starting it could be because of the high amp draw. Research RVsoft start . It is a device that you install on your air conditioner . It allows the compressor to start at a lower current draw. There are other manufacturers of similiar devices. I installed the RVsoftstart on our 2014 Navion and it made a noticeable difference.
The Coleman soft start is about ½ the price of that appliance and does the same thing. However, neither will cover up a high a high amp-draw that is out of spec.
__________________ 2000 Winnebago Ultimate Freedom USQ40JD, ISC 8.3 Cummins 350, Spartan MM Chassis. USA 1SG, retired;PPA,Good Sam Life member,FMCA. "We the people are the rightful masters of both the Congress and the Courts - not to overthrow the Constitution but to overthrow men who pervert the Constitution." Abraham Lincoln
I have replaced several carburetors on my generator and they all need adjusting after. Your gen speed needs to be 62-63hz off load and will drop under load. The large current you are seeing is typical of an air conditioner starting. It can momentarily pull 50 amps then drop to 15 amps. A slight drop in rpm when a load is added is normal but you are starting from too low a point to handle the load. Attached is the adjustment procedure taken from Onan manual 983-0501D. I used a combination of Microwave, water heater and AC to create the loads.
Good luck, Keith
Sorry it took so long to get back but have been dealing with other more boring issues. Thanks to all for your help. I have my work cut out but it is great to have so many knowledgeable people to bounce things like this off of. Once we land next, I will pick this up and start checking. Thanks again to a great community
Keith H or others, I appreciate the attached docs for adjusting the carb and would like to save them, but when I pull them up on my computer, the "save" button is grayed out. Is there a way to save them? It appears that I might be able to print them, but I'd rather have them digitally if possible.
Thanks