As I'm sure many have done, I purchased a $99 Weedeater push mower at Walmart to mow the hard to reach areas of my yard that I can't get to with my rider. This mower is about a year old and has a 3.5hp Briggs & Stratton engine. Late last season, it the engine developed a constant surge in RPMs. I read somewhere that this was probably due to a worn out governor spring, but I left it alone, thinking that this mower wasn't even a year old. Upon starting the engine this season, the surging was gone and the mower ran correctly. A week ago, it was running fine and all of the sudden it quit. I messed with it a little bit, pumped the priming bulb a few times and it runs great for about 10 seconds and dies. I've noticed that this mower and many like it in this price range with this same engine don't seem to have conventional type of carburetors. In fact, I don't see anything to adjust on this thing. If I take the air filter off, I can see where the priming bulb seems to shoot gas directly into the cylinder. I'm thinking that it has to be a clogged fuel line from the tank. Has anyone had a similar experience? This is actually the second mower that I've had that had this same problem. I gave the first one away.
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Walk behind Cheap Push Mowers - Troubleshooting
- Thread starter rloden
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Export threadThe 148cc and 158cc B&S flatheads do not use a conventional float carb. They instead use a carb with a cloth diaphragm. The surge symptom you described it doing before is completely symptomatic of the diaphragm going bad. They go bad really easily, particularly with the 148cc B&S like you have. They never seem to last more than a season on the 148cc. I've gotten a few seasons out of the 158cc without it going bad. The replacement only costs about $3 and it will probably take about a half hour to do if its your first time. There are tons of instructions online about how to do it since this is such a common thing. Since you also need to take the fuel tank off to do it, take the opportunity to clean up the tank and the carb while you are at it. If I recall, the carb is now plastic on these so do not soak the carb in carb cleaner.
I got tired of dont this with the B&S engines so I decided to spend a little more for a mower with an OHV engine this time around.
Edit: they even sell the diaphragms on amazon:
http://www.amazon.com/Briggs-Stratton-5083-Carburetor-Diaphragm/dp/B000KKMAT4
I got tired of dont this with the B&S engines so I decided to spend a little more for a mower with an OHV engine this time around.
Edit: they even sell the diaphragms on amazon:
http://www.amazon.com/Briggs-Stratton-5083-Carburetor-Diaphragm/dp/B000KKMAT4
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Wow! This is exactly the information I was going to look for when I started here this morning. I just sold one of these forlorn pieces of equipment for $40.00 yesterday. If it starts surging, I'll be able to tell the new owner what's up.:biggrin:
One other thing to check is the air filter. I've got one of the 158cc B&S engines on my cheapo mower and it was doing the same surging thing you described. I took off the air filter in preparation for removing the carb, tank, etc., thinking I'd have to rebuild the carb or something. The filter, even though not that old, was completely grimey and caked with dirt. I washed it out, let it dry, put a small amount of oil on it and voila, that was the trouble all along. Its done it once since then and I just recleaned the filter and that solved the problem again.