# Simplicity keeps running rich under load.



## Country Boy

I have a Simplicity tractor in the shop that has been giving me fits. Its a 2006 model, sorry can't remember the model number, but its about one step below the big garden tractors with a 50" deck and a 20 or 22hp Briggs Vanguard engine. The engine runs great when you have it running in the shop, but as soon as you turn on the deck, you get a big puff of black smoke, then intermittent puffs of black smoke as it runs. Customer said it was running fine last year but started to sputter and run rough towards the end of the season. He changed the oil and air filter this spring. The oil was overfilled, but didn't smell like gas. I drained it back down to the full line.

Here's what I have done so far:

-I pulled the air filter and it is clean and dry, but it does seem to run a bit better with the filter off (but not as it should).

-I tested the compression and have 175 PSI in both cylinders.

-I reset the valve clearances because the engine has about 355 hours on it and they were out of the proper range.

-I replaced the sparkplugs because the old ones were just balls of carbon from running so rich.

-I pulled the carburetor and disassembled it. No dirt found, but I blew through everything anyway. The solenoid is sticky, though it seems to start and shut down fine. Will probably replace it either way.

-I reset the float height, thinking that it may not be putting enough pressure on the needle valve. The valve itself is clean, smooth, and soft. Can't see anything wrong with it.

What bugs me is this is the exact same model Simplicity that I had so much trouble with last summer (ended up having to replace one head and redo the valves in the other). It has the same engine and is from the same year. From my research online, it appears these engines have troubles with rich running after a period of running from 50 hours to well over 500. Both of these tractors had between 350 and 400 hours when they acted up. I checked the valves and compression first thing after having so much trouble with the one last year.

Any ideas as to where to go from here? I can get all the carb parts like needle and float and gaskets, but our parts distributor doesn't stock those parts and they will all be special order so I can't return them if I don't need them. It will also take about a week to get them and the customer is anxious to get his tractor back because the lawns are growing like crazy.


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## Mickey

CB, don't have anything to offer but wanted to say I do appreciate all the details you've included.

I have a hard time with some of these *can you help me posts*. All but no information given and asking for help. Sometimes you make suggestions on things to check and they seem to fall on deaf ears. I can appreciate those that don't have decent troubleshooting skills but if they can't at least try and implement the things asked by those trying to help, I just don't know where to go from there.

Hope you can get this figured out.


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## Argee

There are a myriad of possibilities. It could be caused by any one of the following. Weak spark from coil; spark plug gap to wide; bad plugs; dirty air filter; stuck float; clogged muffler. Regretfully, it's a process of elimination until you find it.


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## stickerpicker

Country Boy said:


> both cylinders.
> 
> 
> 
> -I reset the float height, thinking that it may not be putting enough pressure on the needle valve. The valve itself is clean, smooth, and soft. Can't see anything wrong with it.


Will the float actually float? Floats of nearly every design and material have been known to fail occasionally ever since I was a pup. Might pay to check it.


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## Country Boy

Well, I think I got it. 

-To eliminate the float and overfilling of the bowl as a possibility, I pinched off the fuel line, started the mower and then tried the deck. Same thing. So it wasn't overfilling.

-I checked the spark on both sides and its blue hot and consistent on both sides, no missing or weak spark. 

-I hooked up an external tank to the pump and ran different fuel. No change.

Ended up ordering a new air filter for the unit and I noticed that the part number on the old filter and the new filter were different. The new filter ended up being about twice as thick as the old one. Popped that on there with a new pre-cleaner and pulled the spark plugs and cleaned them up again, and now it runs like a charm. Seems the old filter, while clean as a whistle, was too restrictive and caused a partial choke condition. I have a feeling he put the filter on and it ran fine for a while when the filter was new, but as soon as it picked up a bit of dirt, it became too restrictive and started causing it to run rich. The problem would have gotten worse over time. I would have caught this sooner if we worked on the Vanguard engines more. I do a lot with the Inteks, but most of our units have Kohler and Kawasaki engines.

Thanks for the replies, and I hope this info helps someone else out in the future.


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## Argee

Glad you found it. Most times it's something simple, staring us right in the face, sometimes to obvious to see.


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## stickerpicker

It would be interesting to take a water manometer reading of the two filters.


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