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Discussion Starter · #1 ·
Hey guys I'm in the process of rebuilding a '91 Wheelhorse 520-H. This unit has an Onan P220 engine in it. The engine was rebuilt before I got ahold of it and I've discovered multiple problems I've had to correct myself. At first the governor arm wasnt moving at all when the engine was throttled, after taking the engine apart I found a bearing missing that goes at the bottom of the governor arm. This specific bearing is noted in the Onan engine repair manual so I guess its easy to fall out during a rebuild. Now when the throttle is increased I can feel tension on the governor arm as the RPMs increase. This is operating as it should right?

Heres my problem, the engine has no throttle range at all. I raise the throttle a couple of inches and it runs at a full 3600ish RPMs. lower it to the bottom and it idles. I have both the Onan engine manual and the Toro manual thanks to you guys but I still cannot figure this thing out at all.

Current configuration on throttle/governor assembly:
I have a spring that attaches to the throttle cable arm, the spring is rusted but I don't think this causes the issue, tell me if I'm wrong. This spring can go in 3 holes on the throttle cable arm. Then it attaches to the governor arm and there are 4 holes it can attach in here, I've tried almost all combinations with no success.

From the governor arm to the carb is a linkage arm. The governor arm has 3 holes in it and the carb has 2 holes in it. Every diagram I've seen has this linkage in the middle hole of the arm, however my engine races and refuses to idle with the arm in this hole. I currently have it in the farthest hole from the carb (hole facing away from the engine). This arm has a small spring that wraps around the entire arm and has hooks at both ends. This spring is not noted in either manual so I don't know where to hook it up or what its purpose is. The governor arm has a smaller hole in it so I currently have it there and on the other end I have it hooked around the other hole on the carb, I doubt this is right though.

Can someone explain to me the mechanics of this governor and post pics if possible. I can post some pics if it would help as well.
 

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Discussion Starter · #2 ·
Okay so I worked on it some today, with the engine off I can move the governor arm a couple inches freely back and forth by hand, is this normal? When the engine is running and I speed up the engine, I can feel the governor "tapping" on the arm, but it doesn't seem to be enough to keep the engine running at a constant speed. More internal governor problems?
 

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Have you adjusted the governor to match the carburetor? With the engine OFF move the throttle shaft to wide open throttle. As you move it from idle to wide open take note of which direction the govenor shaft rotates and mark it down because you will forget - clock wise or counter-clock wise. Loosen the governor arm clamp so the shaft will rotate in the arm. While holding the carb throttle in the wide open position, turn the governor shaft in the direction noted before as far as it will go and retighten the clamp. Both the carb and governor have to be at max throttle position at the same time for the governor to work.

All the holes in the arms for the spring are to adjust the governor sensitivity. Reacts too quick or slow to react as the engine load changes. This should be in the Onan service manual. Need one?

The light spring on the throttle link is likely to keep the link snug in the levers. They often hook into the same levers the rods do.

As you noted the throttle is hooked to a spring that pulls on the govenor arm and tries to increase the throttle position. The governor tries to decrease the throttle position relative to engine rpm. What you end up with is the balance between these 2 forces.

Garry
 

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Discussion Starter · #4 ·
Hmm mine doesn't have an "adjustable clamp" unless I'm missing it (if I am please tell me, really not looking forward to tearing that governor down again:banghead3). Im starting to think I might have gotten the wrong linkage from my Toro dealer, although it fits perfectly though. Heres all my manual states about the governor, no meantion of an adjustable clamp


Heres a pic of another Onan with the same setup as mine, except my linkage has a spring wrapping around it.


 

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I see Onan is different than Kohler.
Step #2 is going to wide open throttle.
Step #3 The governor lever has a series of holes which accomplishes the same thing.

Garry
 

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Discussion Starter · #6 ·
Hmm well I've already tried all 3 hole combinations there with no luck. I'm starting to suspect a problem internally with the governor, although I have yet to dissasemble the flyball / camshaft center pin assembly as that requires pulling the engine out of the tractor. Has anyone had any experience rebuilding this?
 

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Hi,
Did you ever figure out your problem.I am having the same issue with my onan b43g.
 

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motox
in their infinite wisdom, onan saved a few pennies,
when the started using the plastic flyball ring.
they are noted to come loose and or break.
NEXT the put a tang on the ring and a slot in the gear. (better)
BUT still not as good as the original metal ones.
thank you. boomer (the used onan engine parts guy)
 
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