Community Forums

fallguy · 06-18-2012, 09:57 AM

I noticed that when I travel when it's hot and use the generator and house a/c's that it will run for about an hour or so and then the generator will shut off. I let it cool and then it works great again. I am thinking that it can't get enough cool air to it and therefore overheats and then shuts off. Has this happened to anyone else? I thought about maybe taking a dryer ducting and wire tie it so it can get cool air in there. What do ya think? When it's in the 100's and I'm just sitting running it I have to open the gen door to help it out as well. I do run synthetic oil in it. Onan Emerald 5500 50amp.

Thanks!
Matt

Jim_HiTek · 06-18-2012, 10:52 AM

You might check to see if your AC voltage creeps up in that hour. Also check under the rig for any air blockage, nests, etc.

If the genset has been working for years, and just lately started behaving like this, that would point to a component problem...like in the Voltage Regulator...

If it's always been this way, then you should consider adding an air source.

Springer45 · 06-18-2012, 05:56 PM

Try removing the gas cap. The vent may be failing causing a vaccum in the tank stopping the fuel flow. If this cures it the evap systme on your chassis fuel system will need to be checked.

bjsheldon · 06-19-2012, 08:42 AM

This is the typical symtom of the fuel pump problem with Onan gensets. As they heat up, a rubber seal swells and stops the pump from working. Make sure you get a return guarentee as they are expenseve and at least with me, the replacement from the dealer had the same problem. Chech other posts for methods of determining if the fuel pump is the problem.

azpete · 06-19-2012, 01:52 PM

i have had this problem a few times, till i figured out that the oil was thinning out to the point, the oil pressure sensor on the generator wasnt working. try changing your oil to 20w50 oil. i know this has worked for me. i live in arizona and travel in 120 degree weather a lot. after changing the oil, problem went away. it may be something else, but this is worth a try.

ahicks · 06-19-2012, 06:10 PM

Quote:

Originally Posted by azpete

i have had this problem a few times, till i figured out that the oil was thinning out to the point, the oil pressure sensor on the generator wasnt working. try changing your oil to 20w50 oil. i know this has worked for me. i live in arizona and travel in 120 degree weather a lot. after changing the oil, problem went away. it may be something else, but this is worth a try.

Yes, that's what I was wondering? Stepping back into the 70's when people (and oil companies) were still messing around trying to figure out these multi grade oils, we had a HECK of a time with those oil pressure sensors (or the oil, whatever). Sometimes the oil was so thin/switch so whipped, that they would only run with the start switch held in the start position because they weren't building enough pressure to stay running on their own, even when at room temp!! So azpete's thoughts came to my mind when reading the OP's post as well. We used to put straight 30 wt. in them to fix it back then.

Regarding the expensive Onan pumps, isn't there a 16.00 (don't quote me, maybe they're 25.00) or so generic pump that's a direct bolt in replacement for them?