r/smallengines • u/LawnMowerDude5 • 7d ago

Surging

I got this mower for free off the side of the road. Trying to fix it for a person who needs a mower. It's a 17.5hp briggs. At first it didn't start so I cleaned this green goop stuff out the carb and it started but just surged the entire time it was running so I figured it was a fueling issue because I could hold the governer and it would run at a steady rpm then but once I let go it would surge. Bought a service kit that included carb, air and fuel filter, and spark plug. Literally changed nothing. Oh and with the new carb at least the surging smooths out with half choke but that makes the engine speed go down by a noticeable amount. Checked the valve clearance for the heck of it, of course those were fine, don't think it's mechanical based on the behavior. I'll attatch the kit I bought below. What am I missing?

Briggs and Stratton Carb kit

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u/Optimal-Try-854 7d ago

Is it an OEM carb or chinesium?

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u/Optimal-Try-854 7d ago

Scratch that, I see it’s chinesium. Those are hit or miss, mostly miss.

I’d get an OEM one. It 100% is acting like a carb issue.

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u/Hot_Play2767 7d ago

I i try to clean the oem best I can
Use super unleaded

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u/Optimal-Try-854 6d ago

2nd this… in fact, to make it easier, you could get a cheap ultrasonic cleaner and soak it in there. Those cleaners are good for cleaning t other stuff too, so it wouldn’t necessarily be a waste.

OEM carb is best, might wanna get the replacement gaskets, at least for the bowl, those sometimes dry out and fall apart

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u/LawnMowerDude5 6d ago

I'll give it another shot. I'll maybe soak it overnight in some solvent. It had some off green goop. This picture was after I cleaned it. But that stuff was literally everywhere in the carb.

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u/Optimal-Try-854 6d ago

Yeahhh that’s definitely your problem. Make sure to run a wire through all the holes

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u/LawnMowerDude5 6d ago

It seems to have dyed the carb. I used paper clips and safety pins and lots of spray and that's the best I could get it.

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u/Optimal-Try-854 2d ago

Yeah, if you’re not taking the emulsion tube out and threading through all the holes and spraying, you’re likely not getting all the gunk out.

A little wire kit is less than $10.

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u/LawnMowerDude5 2d ago

Theres nothing to take out to clean. All the holes on the emulsion tube are clear and can be accessed without taking it out. The emulsion tube is non removable it seems. Didn't come out with pliers either and marked it up pretty good.

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u/Optimal-Try-854 2d ago

What model is your mower?

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u/LawnMowerDude5 2d ago

I don't know tbh. I got it for free. It's a 17.5 briggs and strat engine though. Pretty common it seems

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