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Briggs twin 12.5 horse


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Posted
OK, now that my 9020 is down due to the hydraulics not working (see other post) my backup is a model 6212.5 (Takes 5x longer to mow the lawn than with the 9020). While mowing the engine coughed and quit. Now it will run with poor HP only if the choke is almost full on. The filter is clear, the gas is good - does this sound like a carb rebuild is suddenly needed?
Posted
Disconnect fuel line between fuel filter and tank, loosen fuel cap and blow back in to tank to make sure fuel line is clear. Re-connect and try mowing. If problem is still there, it could point to carb work.
Posted
There would be several things I would check before pulling the carb. off. It is possible that being the second tractor and not used as much that you picked up something in the tank that blocked the fuel flow. However with the filter in-place I'd dough that you have a hunk of trash that has all of the sudden blocked the carb up unless it's a flake of debris that was inside the bowl to begin with. Check for good fuel supply and replace the plug and try it. If it persists, then go into the carb.
Posted
Thansk guys! Will give it a try.
Posted
Might also look for a cracked and weathered fuel line. I've had them crack when they are old and brittle which causes a very lean condition requiring almost full choke to siphon gas into the carb past the crack that's drawing in air. my 2 cents.
Posted
If fuel flow to the carb doesn't appear to be the problem, the next thing I would check is the fuel pump diaphragm. The pump is an integral part of the carb on these opposed twin cylinders. You must be very careful in disassembling the fuel pump as there are three springs inside. Nothing is going to fly apart, but you need to be aware so they won't fall out and be lost during disassembly. Just watch closely so you can see where these springs belong so they can be replaced in their proper locations. Another thing to check is the vacuum line which provides the pulse power for the pump. It attaches to the bottom of the fuel pump and to the crankcase. If this is cracked, broken, or has possibly come off, there will be no pulse power to operated the pump. Pat
Posted
While the engine is running you might try pulling the plug wires one at a time and see if it makes any difference. You could have a plug failing to fire.
Posted
Hi guys: Looks like Pat had it right, it was the diaphragm. Somehow a pievce of RED paint chip got inside the vaccum side, wore a hole in it. Unfortunately one of the cover screws broke in disassembly, and had to drill and tal new hole. Now I just got to order the parts and get it back together! Thanks again guys!!
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