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HOW TO FIX surging engine, bogs down with auger, runs only with choke (in one hour, or less)

6.2K views 8 replies 7 participants last post by  Auger1  
#1 · (Edited)
I decided to document a repair on a blower I recently pinched from a seller. Let's make content!

This LCT engine would surge (rev up and rev down) on open choke, and would only idle fine with choke (the second to last notch before a total closed choke). Upon applying the auger, it would starve and almost die.

I don't waste time on replacing the fuel or checking the plug or disturb the throttle/governor or futile attempts to "tune" an otherwise non-adjustable carb. So many folks try all that first, yet still end up pulling the carb. All roads lead to Rome.

Time is money. I get right on it.

Blowers with LCT engines are by far the easiest of OHV's to get access to the carb: 4 bolts off a muffler shield, 4 bolts off a shroud, one choke dial pulled up. Powermore's require more stuff off. Briggs' plastic shrouds are just a PITA.

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I don't use a Vise-Grip which chews up the fuel line or a screwdriver to score up the barb in prying the line off. Otherwise the fuel line will drool around a damaged barb, needing gasket sealer and a tighter hose clamp. Instead, heating up the line so hands can still touch it is all it takes to wiggle it off. I suggest using a personal hairdryer to prevent damage and injury that may come from a heat gun.

The primer hose plastic barb is even more delicate. That hose is easy to replace so I sacrifice it by cutting it.

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Unlike older carbs with hooks and Z-bends in linkage, LCT ones are removed while the carb is still in place. Closing the throttle lets me lift up the link out of the way. Carefully unhook the spring.

Now I can work indoors.

TIME PASSED: 15 MINUTES.

Before removing the pilot jet that is wedged under the idle screw, note how much it pokes out to push the throttle. I don't figure out how many turns-out it is in fear of stripping out a screw made of plastic. Since someone already played with the screw on this Huayi, I measured 3.0mm on a new Stens 520-356.

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Ultrasonic cleaning only needs hot tap water with a shot of ultrasonic degreaser.

TIME PASSED: 45 MINUTES.

After 30 mins, the ultrasonic does a fantastic job. No solvents. No cleanout wires to poke passageways.

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Parts are dried in a minute with blasts of compressed air from my shop air compressor. Work those holes.

The o-rings on the pilot jet will be clean and grippy and may not allow it from properly seating. Use a bit of dish soap on the o-rings to seat the pilot jet back into the carb.

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The bowl is oriented so the drain bolt is exposed for easy side access.

Give the new primer line an extra inch for more slack before reassembly.

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TIME PASSED: ONE HOUR.

With fresh fuel treated with Sta-Bil and Seafoam, it fired up on the first pull.

A Treysit sirometer (Briggs & Stratton 19200 Tachometer) tells me it always had a correct throttle that I never had to mess with.

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And of course, it's one thing after another.

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#4 ·
For some machines, I've taken the bowl off and cleaned it and the main jet with a cleaning wire, reassembled and tested. If this works, I'm done, which is common. If not, pull the carb...

I always dump the gas and start over w known good. This is first.

A neighbor gal had surging a month ago. I tried Liquid Machanic and let it run in her driveway for 10 mins. It worked! Starts great and doesn't require choke after a minute. Tried it on my own blower and it doesn't require choke now either.

Note I'm a hobby repairman. I always give them a bottle of stabil. One mower customer came back every spring until i did this. Have not seen him since.
 
#6 ·
For some machines, I've taken the bowl off and cleaned it and the main jet with a cleaning wire, reassembled and tested. If this works, I'm done, which is common. If not, pull the carb...
I used to do all this before having a USC, most of the times I didn't even have to remove the heat hox. I did find it cumbersome to work under a blower, especially if the main jet didn't want to drop out.

As I did more and more blowers, it was faster for me to pull the carb and USC the whole thing, because 50% of the time it was headed there anyways.

All roads lead to Rome. I just get it over with.

The way I see it, if a carb is able to be (almost) restored with just a poke of the main jet, just thing how clogged up the other smaller areas are. It may work for now, but perhaps not the next season.

My buyers never have issues with my blowers the next season after, and I get referrals as a result of that.

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#8 ·
People seem to report mixed results with the cheap aftermarket. I have one on a 5 hp tecumseh snowblower. Suddenly started flooding. I do tip these forward to work on them so maybe a factor. I dropped bowl only but then float dropped and needle fell out so I removed carb completely. Unlike tecumseh it has brass seat and viton tip needle. Fat chance of getting replacements. Cleaned bowl and flushed line. So far not flooding again.