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Discussion Starter #1 (Edited)
I have the famous 8.5 hp Craftsman model 536.881850 which will stall after a load is put on it - usually when I engage the auger. This typically happens when the engine gets wet with snow, and I put up with all of this long winter. After researching numerous threads on this forum, it looks to be a common issue. Based on some of the suggested solutions from this forum, this weekend I finally got around to installing a new ignition magneto module, and changed the carburetor to the updated Briggs & Stratton part no. 590907. The engine started 1st time and appears to run strong, but have no idea if this will resolve the issue till next winter when we get some cold winds & wet snow again.
My question - to anybody else that has done the above upgrades, have they been successful in overcoming this annoying problem?? I sure hope I have a more reliable winter next year!
 

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hello cargy, welcome to SBF!! it might be awhile before someone answers this cause there is less activity during the warm weather months
 

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yes new carb fixed carb icing on B&S 1150/8.5HP OHV

Cargy,

I'm the one who posted about carb icing fixed with carb kit Briggs & Stratton 590907
Yes I'm convinced it is fixed for my 881850.
I have seen no stalling since I put the new carb on last fall the fall.
One problem with my data is that I"ve only put 10 hours the whole season, as this blower is at a property that has plowing service.
Motor seems to run smoother, and not even any popping as before.
Always starts and restarts under any condition.

For background: Motor is B&S: 15A114-0342-E1 it is OHV, not flat-head.
As you state, the motor would bog down after about 1/2 hour in wet conditions. For me (and my neighbor's 6.5HP) we would have to cover the motor with a tarp and run a hairdryer at the motor for 30-60 minutes, and then it would fire right back up. Classic symptoms of carb icing.

I found a John Deere service bulletin instructing the techs to block the blower housing intake. This would cause the motor to run warmer, in order that the extra heat would conduct to the carb.
There is also a Honda kit to fix carb icing.
A poster long ago, (not sure if SBF) also fixed the problem on the same B&S motor as ours, by blocking up the holes at the blower housing....


Let me repeat what I think is not the cause:
Not Vapor Lock: My test runs were 1 hour (2 sessions each) at 50deg F.
Not Bad Coil: Coil would take a lot longer than 1/2 hour to 'dry out'. I did not replace my coil.

I'm the most biased SBF member who is active on this topic, but I think you are in the clear. Good Luck.
 

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I think before changing anything I would have sprayed the engine down with a garden hose sprayer in an attempt to replicate the problem. Then changed the parts and tried the hose again.
 

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Discussion Starter #5
Thanks conwaylake

Thx for the feedback conwaylake - it was your threads that got me going in this direction. Good to hear that you think changing out the carb did the trick. As an aside, based on some original feedback on this topic, I went back to day & checked / set the valve lash on this ohv motor - I set exhaust to .010" & intake to .005", though neither appeared to be out of spec, if at all after 10 years. I wish I had come across this forum earlier in the snow year & could have saved a lot of hassle. Thx again.
 

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Tough to test with a water spray

You can't force the same conditions by simply spraying water.
Has to be near or below freezing, and humidity has be high, which is not
easy to replicate. Water vapor in the air is not the same as water droplets from a hose or spray bottle.

And before I replaced the carb, I did that (water spray/soak), because I wanted to make sure that the coil wasn't causing me problems. Coil and engine survived a real soaking. I even spayed water with a mist bottle into the carb throat and it only bogged down slightly during each 'dose' of spray.

But, I have to stress that this was on a dry mid October day at 45 degF.
 

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Discussion Starter #7
Jan.1/16 quick update. Had the first 2 snowfalls since replacing carb. The snowblower ran like a champ. Ithink this solved the issue. Many thanks to conwaylake. If anyone else has the same problem with the 8.5 hp Briggs, this appears to be the solution.
 

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Cargy,

I have an an update as well. Just ran my for 3 hours this weekend (3 separate 45-60 min sessions). No problems.
Conditions were close to the 'Worst Case': 33-36 degF, Moist air.
My machine is a 2006 Craftsman 8.5HP / 27 in. Carb kit only. did not replace the coil.
 
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