Surging mower video

[polk county]

This is a MTD model number 11A-54M7031. It was running fine and started first pull until it ran out of gas, then it wouldn't start. I pulled the carb and sprayed carb cleaner through the jets and then blasted with compressed air. It starts now but wont stop surging. In the video you can see how I manipulate the choke and throttle to get it to run momentarily. Any ideas as to why this engine is surging? Thanks

 

[sutor623]

I have had that happen on one of my mowers when I had an air leak from the carb gasket. Almost like it is "searching" for something, trying to richen the mixture up by closing the butterfly..........

 

[tpenfield]

+1 ^^^ usually surging is caused by a lean fuel mixture. if the has a needle valve under the carburetor bowl, you can try opening the 1/2 turn. Often some gunk gets stuck in the needle valve and makes the engine run lean.

 

[Scott Danforth]

^ +1.

you have to pull the needle valve apart usually to get the dirt out. those little passages make really good filters when you run out of fuel and suck up the carp in the bottom of the fuel tanks on lawnmowers.

 

[bigdee]

Just fixed a generator yesterday with same issue. Ethanol was the cause....cleaned carb jets and passages with fine wire and compressed air.

 

[Grub54891]

As stated above, some will not run correctly with the airfilter not on there also.

 

[hungupthespikes]

We take it you reused the old carb to motor gasket?? Any leak around the gasket will cause surging.
If you get close to a welding supply store try and pick up one of these.
http://www.ebay.com/bhp/welding-tip-cleaner

 

[K-2]

My pressure washer does not have a metal seat for the needle valve. The needle valve seats in this little doughnut shaped O ring. It's not rubber,
but it swells and distorts, probably from ethanol, maybe Sta-Bil . Very cheaply made . Shipping was more than the parts.

 

[Cofe]

The newer carbs on these small motors don't have screw mixture needles anymore. The newer carbs have a ported passageway that is difficult to unplug. The only way that I have been able to get them to work again is to put the carb in a ultrasonic cleaner for half a day, and then blow out all the passage ways with carb cleaner and pressurized air. Sometimes it takes two attempts to get the decomposed rubber fuel lines out of the passageways. If all else fails, ebay has new carbs for about 30 bucks. Another option is to rob an older screw adjustable carb from another older motor.

Another thing to mention, is to install a shut off valve in the fuel supply line, and run the motor out of fuel after each use to help with future problems.

 

[stackz88]

if its a briggs/stratton engine it might be one of the ones with the paper fuel pump. they like to distort and give that exact issue. its about $4 for the repair from true value. I love seeing these mowers on the side of the road in my neighborhood in the spring. I drag them home, put a new pump diaphram on and sell on craigslist for $75.

free mad money.