Mower surges when cold

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pburlison6

Forum Newbie
I have a 18.5hp briggs on a craftsman mower. Model and Type:31P777-0299E1. I have 2 problems. The mower is hard to start and surges when cold. After it warms up it idles smooth. I assume it is a air or fuel problem. I put new air and fuel filter, cleaned fuel tank, adjusted the valves, and rebulit carburetor. The surgeing and hard to start problem wasn't there before replacing filter and rebuilding carburetor. The fuel mixture screw doesn''t change the way the mower runs, (idling, or fixing surging problem). When rebuilt the carburetor I wondered if I didn't push the seat in far enough, would that cause these problems?
 
pburlison6 said:
I have a 18.5hp briggs on a craftsman mower. Model and Type:31P777-0299E1. I have 2 problems. The mower is hard to start and surges when cold. After it warms up it idles smooth. I assume it is a air or fuel problem. I put new air and fuel filter, cleaned fuel tank, adjusted the valves, and rebulit carburetor. The surgeing and hard to start problem wasn't there before replacing filter and rebuilding carburetor. The fuel mixture screw doesn''t change the way the mower runs, (idling, or fixing surging problem). When rebuilt the carburetor I wondered if I didn't push the seat in far enough, would that cause these problems?
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Yep the seat could be the issue. Have you had time to check to see if it is in there right yet?
 
What seat are you talking about? Needle valve seat? If that seat is wrong your float level wouldn't be right. If not what other seat are you talking about?
 
If you are talking about the inlet needle seat, that would not cause the troubles that you are having. Did you change the main jet? if you did, put the old one back in.

Also make sure the choke is closing fully.
 
I didn't change the main jet. The rebuild kit didn't come with one. I did remove it and cleaned it then reintalled. The needle valve seat is the one in question. The seat the float valve sets in when the float is raised.
 
pburlison6 said:
I didn't change the main jet. The rebuild kit didn't come with one. I did remove it and cleaned it then reintalled. The needle valve seat is the one in question. The seat the float valve sets in when the float is raised.
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With the carburetor upside down I would say the float should set level. Does it screw into the carburetor body or press in. If it pressed in I have to say I have never changed one. If it screws in it seats up to a gasket.
 
reynoldston said:
With the carburetor upside down I would say the float should set level. Does it screw into the carburetor body or press in. If it pressed in I have to say I have never changed one. If it screws in it seats up to a gasket.
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If it is the rubber one that presses in use the back end of a drill bit (Not the sharp point) that will fit into the passage and push it in all the way.
 
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