Cummins/Onan Generator

[aphilliph]

I have a 2019 305RL and had a Cummins/Onan 5.5 lp gas generator installed when we purchased the unit last year. Have been keeping up on the routine maintenance of the unit with oil and filter changes every 150 hours per the owner's manual. I recently changed the oil and oil filter, but not the air filter since that was done last oil change. It ran fine for a couple days, even powering the AC for a few hours, then yesterday it had a hard stop and wouldn't start again, around 15 hours since the oil change. When trying to start, there is a loud popping sound coming from behind the air filter, the carburetor. It sounds like the motor is cranking, but isn't starting up and only making the repetitive popping sound as it is turning. The prime seems to be slightly different now too. If I recall correctly, when I primed it prior to this issue it would click multiple times until I try to start it. Now it only makes one click no matter how long I hold the prime down. Anyone ever had similar issues or know what might be causing this? Up in the mountains now but have tools with me and wanted to see if there was anything I can do before we have to head to a mechanic.

[jetskier]

1) You shouldn't have to prime an LP gas Onan. The prime setting is for the gasoline models only. The 5500 unit I moved from my old trailer (2005 model generator) starts even today in about 3-5 seconds of cranking.

2) The Onan LP generators don't like to be run off the LP tank that has the secondary regulator as it reduces flow (side opposite the changeover valve). Try switching tanks to the side with the changeover valve.


3) If that doesn't work, you can purchase a separate LP regulator and plumb it directly to the generator to rule out a gas or regulator problems. That's how I discovered the secondary regulator problem on mine years ago. A new secondary regulator works for a while, but then the flow diminishes over time.

[aphilliph]

Hi jetskier, thanks for the reply and info. Just tried to change it from the tank opposite the changeover valve but still didn't start. I will have to give the separate regulator a try. My first thought was a fuel issue since it does seem to be turning over just not starting.

[Hblick48]

Originally Posted by aphilliph

Hi jetskier, thanks for the reply and info. Just tried to change it from the tank opposite the changeover valve but still didn't start. I will have to give the separate regulator a try. My first thought was a fuel issue since it does seem to be turning over just not starting.

Fuel plus spark at the proper time, can't be anything else.