Onan P220 Governor Problem

[muz123 1,191]

After running my 520 around for 20-30 minutes, when I give it throttle the RPMs will shoot right up. The engine races a lot. If I idle it down and rev it back up, the RPMs will increase over what they should be. I replaced the carburetor with a NOS Onan one, replaced the intake manifold gaskets and re-sealed the intake. Not sure how to fix this problem. Could it by the fly-ball governor spacer? Not sure. Thanks!!

[JCM 9,122]

1 hour ago, muz123 said:

. Could it by the fly-ball governor spacer? Not sure. Thanks!!

Good possibility.

[cleat 5,767]

Maybe but if it was fine until you replaced the carb then maybe something is just not hooked up right.

 

 

[lynnmor 7,285]

If the engine over speeds when it is hot the plastic flyball spacer expands enough to slip.

[Bill D 1,888]

Sounds like the spacer to me.  I've changed that spacer.  It's not too hard, but it does require patience and attention to detail.  It took me about 6 hours, but I worked slowly as there is little room for error on a job like this.  The job can be done with the engine in the tractor, unlike John Deere. 

 

There are some used steel spacers on eBay for sale and an aluminum one on Amazon.  

 

If you haven't changed the ignition module, now would be a good time if your budget allows.

Edited June 11 by Bill D

[lynnmor 7,285]

Here is a link to instructions for replacing the flyball spacer.  In step 18 there is a photo with a yellow arrow, note that the fork on the shaft isn't centered with the hole, this is because the ball under the shaft isn't there.

[Bill D 1,888]

Onans have the most serviceable governor of all the engines Wheel Horse used.  All the others will require complete engine disassembly to repair if the governor fails.  If you buy a used Onan powered machine plan on a governor repair.  Pretty much inevitable from what I've seen.

Edited June 12 by Bill D