Briggs & Stratton running rich

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  #1  
Old 06-02-01, 08:25 AM
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Question

I have a Weedeater 22" lawnmower less than one year old. It has a Briggs & Stratton Quantum XM 4 HP engine that is running extremely rich. So much so that it misses terribly and it fouls the spark plug to the point it quits running in 10 minutes time. Air cleaner is clean, gas is fresh and I have tried everything I know. The carburetor on this engine IS NOT ADJUSTABLE. That is straight from the manual.

What do I do to get this mower running correctely?
 
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  #2  
Old 06-02-01, 08:55 AM
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Arrow Conditions Worth Checking Into

Hello: Teddford

That's correct. The carb may not be externally adjustable but internally the float is most likely stuck in the down position. {Can be one of the conditions discribed below.}

A stuck float, in the down position, will allow the needle to be in the down position also, which allows the fuel to flow in uncontrolled. May also have a tiny amount of debris on the seat or needle. Hindge pin on the float may have restricted float movement or the float has a hole in it.

If the carb is a diaphram carb. The diaphgram is not fluctuating correctly which creates the same condition as stated above. The tiny needle will then remain open. Usually this is do to it having a hole in the diaphram or it becoming dried out. May also have a tiny amount of debris on the seat or needle.

Good Luck,
Tom_Bartco
Accurate Power Equipment Company.
Small Engine Service and Repair Technician.

 
  #3  
Old 06-03-01, 07:53 AM
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Unhappy Thanks Tom, still having problem though

Hi Tom:

I spent 3 hours Saturday disassembling the carb and cleaning it all with a fine tooth comb. I'm not sure of the type of carb I have. In the cylinder below, it has what appears to be a plastic float that allows the pin to open and close. I looked at the float and it is in good shape.

Once I got everything put back together and started the mower, it still is running as rich as ever. There was some trash in the carb before but it is all as clean as can be.

This is really depressing!
 
  #4  
Old 06-03-01, 09:03 AM
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Hi teddford

Question? Did you do a float test on the float?
When the float was out of the carb, did you float it a small container to verify it would in fact float and continue to float for 30 minutes or so? May have a tiny hole or small hairline crack. If so, it will fill up and sink allowing the carb bowl to overfill.

Another remote possibility could be a loose seat or deteriorated gasket under the seat on which the needle sits when the float rises. May be a bent fuel needle inside the carb. What this means is gas seepage passed the needle and or seat.

Check for a vacuum leak in any hose other then a fuel line hose going to the carb. Also check for a restricted crankcase breather. Cyclinder intake stroke could be drawing in too much air thru the carb as a result.

Many of the above suggestions are far reaching assumptions granted but worth checking into, since the easiest solutions aren't working. Unless you have overlooked something during prior attempts.

Good Luck,
Tom_Bartco
Accurate Power Equipment Company.
 
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