Mower Sputtering But stays Running

halogenmoon · May 8, 2012

So I've got a Bolen by MTD with a Briggs and Stratton 550 engine. It has started sputtering while I'm cutting grass. It acts as though it's about to die, then revs back up, then revs down, then up. Does this in about 1 second intervals but never actually dies. I've changed the spark plug, drained all gas and replaced with fresh bought gas, changed the oil, cleaned the filter, and tried adding Seafoam carb cleaner. Have also checked to make sure the vent holes in gas cap aren't blocked. Still having the problem and have no idea what to do next. Please help!

DaveTN · May 10, 2012

halogenmoon said:
So I've got a Bolen by MTD with a Briggs and Stratton 550 engine. It has started sputtering while I'm cutting grass. It acts as though it's about to die, then revs back up, then revs down, then up. Does this in about 1 second intervals but never actually dies. I've changed the spark plug, drained all gas and replaced with fresh bought gas, changed the oil, cleaned the filter, and tried adding Seafoam carb cleaner. Have also checked to make sure the vent holes in gas cap aren't blocked. Still having the problem and have no idea what to do next. Please help!

With the "hunting" up and down rpm, that indicates a fuel starvation problem. With the carburetor on top of the gas tank, it has a diaphragm between the carb and tank. Even running cleaner through might not help. I would clean the top of the tank where the carburetor joins it and check the diaphragm. Replace it if it's brittle and stiff. Might just clean the top of the tank out while you've got the carb off. Sometimes dirt, water, grit, will get in that area. Hope this helps.

SONOFADOCKER · May 10, 2012

Check the tank , lines for dry cracks. Check carb mount bolts for looseness and the manifold to .
Up/down rpm can be air induced issue to - sounds simple . Break out the bright light and magnifying glass !

SYE Brand · May 10, 2012

Sounds to me like the gas in your fuel lines might be clogging up the flow of gas to the engine. I'm the brand manager for a product called Start Your Engines! which is a fuel additive developed specfically for this sort of problem.

Without trying to sound too much like a salesman, I wanted to put out some information about a product we're proud of that does a great job of dissolving gunk in fuel lines and gets equipment started immediately. Let me know if you'd like more information. Or just google the brand or find it on Amazon - the reviews speak for themselves.

If you want to save time, pour Start Your Engines! into your fuel tank and give it a few minutes to dissolve gum and varnish that's clogged your carburetor and fuel line.

Let me know if there's anything I can help with. Thanks!
Kevin O.

SGL1 · Oct 8, 2014

I have a similar issue. MTD Yard Machine with B&S 550e engine. Runs good but sputters intermittently. I run Shell 89 with Seafoam always and use synthetic 10w30. Plug is good, brand new air filter. Cleaned carb.

Rokon · Oct 12, 2014

SGL1 said:
I have a similar issue. MTD Yard Machine with B&S 550e engine. Runs good but sputters intermittently. I run Shell 89 with Seafoam always and use synthetic 10w30. Plug is good, brand new air filter. Cleaned carb.

Follow the above comments from the original 2012 posts.

Even if you could buy your fuel directly from the refinery, you can still get fuel contamination. (Look for a little man rowing a boat in the watery part of the fuel :dance1

DarrelMason · May 25, 2018

Run some gas treatment in it it solved the problem for me when i run across the mowers that get that same problems

Boobala · May 25, 2018

Surging carburetor is usually the low speed side of carb., best bet is to remove the carb, and do a thorough cleaning,( rebuilding it would be better) check out this site, .. find your briggs carb. and follow the directions, be sure your tank and fuel-lines (replace lines) are immaculate.

http://outdoorpowerinfo.com/repairs/#id_briggs

Mower Sputtering But stays Running

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halogenmoon

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DaveTN

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SONOFADOCKER

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SYE Brand

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