Bad luck with Chinese carburetors lately.

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JTK

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While I usually have great luck with inexpensive mail-order import replacement carbs for OPE, man has my 18.5hp Briggs 31P777 series engine proven to be challenging in this area! I had some issues earlier this year which warranted replacing the original ~2007 OEM carb on this engine. The first replacement eBay carb came with a misaligned choke, that I was able to fix short term, but iteventually broke all together. The second eBay replacement was fine aside from the electrical connector to the fuel shut-off solenoid not allowing the wire from the tractor to lock in properly, plus a very slight fuel weep from the solenoid somewhere. Today the mower wasn't acting right and I discovered sparks from both ends of the throttle shaft and the little fine wire return spring on the throttle was glowing like a light bulb filament! WTH!! If you pull the fuel shut off solenoid wire the sparking stops (but obviously kills the engine). Killing the ignition also stops the short. I'm assuming the solenoid although doing it's job, has an 'electrical leak' going on? Never ran into this one before. Luckily I've got 2 other solenoids from the other 2 carbs to try to swap to.
 
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Buy Kehin (Japan) or similar established brands. They don't cost that much more than Chinese knock-offs. I think B&S OEM is Nikki (Japan), but check to make sure.

All solenoids and relays are prone to failure.
 
I hear you, but you can buy 5-6 Chinese carbs vs one OEM Nikki carb, that you're REAL lucky to find by mail order for $100. Honestly, comparing them side by side, even disassembled, they look and feel identical. This doesn't mean the same I know and have obviously just experienced. Still worth a try IMO for a mower I can live without.
 
I buy alot of carbs and although they are cheap they alot of times are not direct replacement. Still getting a chainsaw carb for $6.00 shipped versus $40 for a factory one or $13.50 for a Chinese Honda carb is a good deal. The Honda carbs are very lightweight and cheap. A better option is rebuilding the old carb but if it's broke, it's broke and not worth the cost of factory.
Can't rebuild a walbro for what you can but a new Chinese one for shipped.
 
Sounds like a fault in the solenoid. The carb is not solidly grounded to the engine (since it's a plastic intake manifold) so if the carb body becomes live, the electricity will find some path like the throttle linkage.

So yes swap out the solenoid should be OK.
 
Originally Posted By: mk378
Sounds like a fault in the solenoid. The carb is not solidly grounded to the engine (since it's a plastic intake manifold) so if the carb body becomes live, the electricity will find some path like the throttle linkage.

So yes swap out the solenoid should be OK.


^ Thank you!

My thoughts as well. Like you say, the carb is insulated from the engine, as is the choke linkage, given the choke shaft and linkage attachment point is plastic. The only metal on metal is the throttle linkage to the engine/chassis. The ridiculously thin wire return spring that is sort of wrapped around the throttle linkage gives enough resistance that it was glowing! I'm glad I caught it and it didn't burn away or worse. Tomorrow I'll swap carb solenoids and post back.
 
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The solenoid should have two wires, one power and one ground. If the plug is wired backwards so the ground actually gets powered, that would cause this problem.
 
Swapped out the fuel shutoff solenoid and the problem went away. The old one was always damp with gas, so I'm assuming it had some type of internal leakage through the coil area. While I was at it, I added a plastic fuel shut off I picked up at my local Napa. Should have done that years ago.
 
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