P220 running rough or not at all

[vt92 0]

Hello,

I have a 1983 vintage wheel horse520H with the Onan P220. I did a thorough cleaning of the carb this spring and the engine had been starting and running great.

Today, I started her up and mowed for about 30 seconds when the engine started running rough, surging from idle to full speed. It seems to be running very rich, like the choke is closed. I pulled the air cleaner and cleaned the foam filter as best as I could. There was gasoline residue inside the air cleaner housing.

I re-started the engine and the same behavior continued, even without the air cleaner. I shut it down and sprayed some carb cleaner down into the carb. Now it will not start at all!

Any ideas?

[stevebo-(Moderator) 8,060]

buy a new carb and it will fix evrything. been there and done that !! they are difficult carbs to clean. by the way your 520 is a 93..typo??

ps :)

[vt92 0]

What does a carb cost?

Based on the serial # it is an '83.

[motox25 36]

I have a 520H with a P220 in it and I did a light overhaul by removing the air cleaner and top half of the carb, once I was in there I just used some carb cleaner and cleaned out the float bowl with it still mounted (didnt want to replace gaskets), and that did the trick for mine, might give that a try before you replace the carb. If your jets are plugged try a wire brush, those small bristles work well on the jets.

[MalMac 1,328]

Well there seems to be alot of this going around. I had the same problem and had cleaned mine several times. That seems to be the answer that I kept getting from everybody I talked to. I got tired of cleaning the carb and like Stevebo I put a new one on. Now it does not surg it just coughs and spits and runs rich. Before investing in a new carb keep trying to make sure you clean it good and change fuel line and fliter. The new carb I got was a NOS carb off Ebay for around 100 bucks.

[flyboy1015 0]

I too have a 520-H with a p220G and had the same problem after it had sat for a few years. Here are the things I've run into on mine:

1. Make sure the fuel flow from the tank to the fuel pump is good. My screen had gotten clogged up and it would lean out after running for a while during mowing. It would get bad enough that the engine would die and only restart after waiting for several minutes.

2. Take the top of the carb off and clean the passages and such. The lower part of the carb has the float in it. Pull the float and check the bottom of the bowl. Make sure there isn't a bunch of gunk in the bottom. There is a drain plug on the side that you can use to get access to the main fuel jet with the stem on your can of carb cleaner. When you're done, replace the plug, float, and top of carb.

There are three screws that hold the air cleaner "pan" to the top of the carb. There are two 3/8" bolts that hold the pan to the framing that is attached to the engine.

The top of the carb is held on with 4 screws, if I remember correctly. You'll also have to disconnect the choke linkage between the top and bottom parts of the carb. This is easy.

The drain plug is about a 1/2 or 5/8" plug, I think. It is fairly easy to get to and remove. Be careful not to lose the pin on the float when you remove the float.

That will take care of your basic carb cleaning. If it is as simple as doing this, and you are pretty good with tools, it would be cheaper than buying a new carb. This is assuming that you don't actually need a new carb.

Have fun!

[vt92 0]

Thanks for all the comments. After sitting for a couple of days, it runs fine now. Go figure.

I will take Flyboys's suggestion and do another good cleaning.

[Rideawaysenior 25]

VT92,

The list you looked at may have bad info. The 500 Series were not introduced until 1988.

In 1983, the equivalent would have been the C175 or even the C195 which both had Kohler power plants.

In any event, the Onans are great engines however the carbs are issue ridden especially if they get a little bit dirty. There are so many things you could investigate here. You may want to try another carb cleaning, check your float and maybe even replace the fuel lines.

Not sure what your cleaning process is, but after soaking the carb in carb clean for a while, I follow up with another cleaning with an aerosol can of carb cleaner followed by blowing out the jets with compressed air.

It's involved, but it works.

[vt92 0]

Thanks for correcting me, though I guess I don't own an antique after all.

I have a document that I got somewhere on the internet which is supposed to be a decoder for the model number / serial # info. This document only goes up to 1984. Maybe this was before Toro bought wheel horse.

How can I find out for sure what year my mower is?

[520HC 207]

VT92 first 2 digits of the engine serial # is the year of production on a Onan. Your tractor will be that year or a year newer due to assembly time.