Onan 5500 problems

Hello all. We recently purchased an 08 Cyclone 3912. Generator had 199 hrs on it and worked fine during PDI. Once we got it home ( Fresno, ca to tacoma , wa) generator would not stay running more than a few seconds. Seems to of been old fuel stirred up in tank. I flushed tank and furl line. Replaced both fuel filters and spark plugs and cleaned carb. Finally got it running and powering everything. During our first trip in it I'm having to constantly adjust the altitude screw just to get it to run 1 ac. It won't run both at same time or even 1 ac and water heater as well. The air filter is now soaked in fuel and dripping out of air box as carb constantly spits black tar looking fuel out. Most of the time when the generator increases rpm for initial ac load it floods itself out no matter how the altitude adjustment is set. Any help would be much appreciated. At this point I'm thinking of replacing the carb

Oman 5500 problems

There are several things that can cause this, low oil pressure or level, generator being more than 11 degrees out of level, etc... The fuel and filter is an easy fix (drain and replace), but I would check your oil level and how level the fifth wheel is first.


Rod Ditrich

Re: Oman 5500 problems

Oil level is full and trailer is level

For all 5500 owners. Had the same issues as discussed. Onan has a recall on the fuel pumps for the 5500.
I'm not sire what models or serial numbers it covers but it does cover mine. Onan division of Cummings are extremely nice to deal with. Good luck. Ed

Ed thanks I've had some issues from time to time. I'll have to check on the recall


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eka217 said:

For all 5500 owners. Had the same issues as discussed. Onan has a recall on the fuel pumps for the 5500.
I'm not sire what models or serial numbers it covers but it does cover mine. Onan division of Cummings are extremely nice to deal with. Good luck. Ed

Click to expand...

Where did you see a recall? A google search turns up nothing.

Contacted Onan with the part number and they told me. Had it fixed today parts and labor were covered under warranty


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Was told by Onan that Carb is shot. I replaced Carb last week and still same problem. Took to local RV repair shop and found out the valves were out of adjustment.