Onan Marquis Gold 5500 shuts down after 20 minutes

Question

I have a 2007 Weekend Warrior trailer with an Onan Marquis Gold 5500 gas generator. As I've seen posted in the past, mine will run for about 20 minutes, then shuts down.  It shows a 36 error code (gas related). I've had it at the Cummings repair shop 4 times now (yes, Onan generators are made by Cummings), and have thus far spent over $600.00 to no avail.  They've replaced the circuit board, drained the gas tank and bolied it out and tested the fuel lines, replaced all filters, changed the oil and it still keeps shutting off. They keep telling me they've checked the carb and altitude sensor, and it is not the problem. Does anyone have any advise?

96bounder30e · Answer

A few years back I had a similar problem with my Onan 4K.........it would run fine for about 20 minutes and then shut off and would not restart until it had cooled back to pretty much ambient temperature........it was not fuel related because I could spray starter fluid in the carb while pushing the start button.....and nothing.......not even a pop.......

The spark plug was getting spark........but apparently it wasn't enough....

In the end I replaced the magneto mounted behind the flywheel.......about $80.....it has not hiccuped since.......

You may have a similar issue......Good luck!

wyotraveler · Answer

That is the problem I was having with my 5500 Onan. Mine had 128 hours and under warranty. They replaced fuel pump on mine and all seems OK now. Another RVer had the same problem and bought a non Onan fuel pump from Amazon and also solved his problem. Apparently the fuel pumps are destroyed by heat. He replaced his with an Airtex E11015 fuel pump.

BTW mine was also throwing code 36

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Onan Marquis Gold 5500 shuts down after 20 minutes

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