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Discussion Starter · #1 ·
Hello,

I have read many forums and they've told me everything I've already tried. Maybe someone else has an idea. I have a Craftsman LT1500- 17.5 HP Briggs&Stratton Silver Edition Engine. It's a 2012 model. (Model#: 247.288812)
(Serial#: 1B202B30416) (Engine model#: 31C707) (Engine Type: 3346 G6)

The main issue I'm having is that the mower surges at high idle. I bought a new carburetor, replaced the gaskets, new gas, new filter (and ran it without a filter), have cleaned the new carb multiple times, made the spring tighter on the governor to see if it was worn out, adjusted the governor and idle screws every which way, I've put the cover over where the air filter goes too. This happens with the old carb and the new carb. It idles good, runs good on high idle for about 5 seconds. After 5 seconds it starts to surge at high idle or under a load. You put it back down to idle for a few seconds, rev it back up to full throttle, it does good for another 5 seconds, or so, and then it'll surge again. When it surges and you spray carburetor cleaner in the intake it'll run perfect on high idle until it burns off all the carb cleaner. I can make it run perfect without any hesitation or surging if I remove the filter, place my hand in a cone shape over the hold where the filter sits and restrict the air flow. As long as I keep my hand there, the mower runs perfect at any throttle position. I bought an LT2000 and it started doing the same thing.
 

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Maybe there is a vacuum leak at the intake where it bolts to the engine. sounds like it's running lean possibly getting air in somewhere after the carb. Try spraying carb cleaner around the intake manifold area and see if it affects it while its running.
 

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If you don't have carb cleaner you can use propane or mapp fuel from a torch....just aim it at the area described by moostang in post#2 without flame...if it smooths out...there is your leak
 

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Discussion Starter · #5 ·
I've sprayed starting/carb cleaner over all the ports where air would come in, along with all over the carb, and there is no change in rpm; it still fluctuates. I cannot hold the governor still. It never dies when I hold down the throttle. I take off the carb and there is plenty of fuel in bowl every time. I take it off when it is surging to see and the bowl is always plentiful. When the foam piece to the governor shaft is sprayed with carb/starting fluid it will jump in rpm and level out/run smooth on high idle
 
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