Generator setting

[RC9660]

I have an Onan 5500 generator on my toy hauler and it starts fine at my home which is 2200 feet in elevation, but at 8000 feet in elevation when I go to the mountains I have to remove the air filter and hold the butterfly valve in the carburetor open to get it to start. Once it runs a few minutes I can put it back together and it will run

I know there is an elevation adjustment on the generator. I also discovered that the plastic knob around the vale stem just turns freely and does not turn the valve itself. So, in order to make it start at the higher elevations I should be able to slip the knob off and turn the valve with pliers. But do I turn it clockwise or counterclockwise and should it require one half turn or two full turns or whatever?

 

[B52Bombardier1]

Hello,

Your generator is starved for air at that elevation and is now running a rich fuel mixture - take a look at a spark plug -- probably black and sooty.

Do whatever it takes to let more air in or to remove some of that excess fuel from the carburetor mixture. Make small adjustments and recheck.

Here is the kicker to your situation and EXTREMELY IMPORTANT. BEFORE you return to lower elevations, you must correct this fuel mixture back to what worked at 2200 feet elevation. Otherwise, your mixture will be dangerously lean, hot and damaging inside the combustion chamber . . . think melted piston top here.

Take precise written notes with pictures as to exactly what you are doing to the mixture to help set things back to normal.

Rick

 

[Joe Hogan]

Check this out.

 

[Kevin D Pem]

So the adjustment is the main metering orifice. All small engines can be "jetted " for the elevation they will be used at. However most small engine shops don't know how to do this.

Another story!

Moved to one of the mile high cities from Phoenix. My Toyota went down hill when I did. The gas mileage went from fair to, well, not great!!! When I went skiing performance was dismissal. .

So with my constant trips to and from Phoenix, I realized I would always suffer some kind of performance problems.

My answer was a diaphragm actuated needle main valve jet.

If most of the use is in the mountains, have the jets sized for that elevation.