Engine Surging


Old 05-20-03, 11:14 AM
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Lawnmower still surges even after carb cleaned

I'm having trouble with my 5hp b&s lawnmower. Last season it would not run so I cleaned the carb twice. The second time I used compressed air to make sure all the passageways were open and paid particular attention to the screw at the bottom of the fuel bowl. After I finished the lawnmower ran but still surged horribly, like it was getting enough fuel one second and not enough the next second.

This season the lawnmower is back to not running on its own again. It will start up and immediately die. I can keep it running (and it sounds very strong) if I continually push on the primer bulb about once every 2 seconds. This leads me to believe that it is still a fuel delivery problem that I am having. I will be cleaning out the carb once again this weekend but doubt it will fully cure my problem. Any ideas what else to look at while its torn apart?
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Old 05-20-03, 06:45 PM
engine ear
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i had the same problem on my old lawnmower also. i realized that there was a switch hidden on the carb that controlled the tension on the spring that goes to the lever connected to the body of the engine. if you get that. i think it is some sort of engine controll switch. if you have it and if you flip it that lawnmower should run like normal.

my guess is that when you decided to clean the carb you might have accidentally flipped the switch
Old 05-20-03, 07:32 PM
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Location: southern louisiana
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If turning the needle adjustment screw counter-clockwise doesn't cure the problem, then you will need to replace the diaghragm in the carburetor. The diaghragm is easy to replace and will cost under $5.
Old 05-21-03, 01:23 AM
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Hello extremesanity!

You are right, you do have a fuel delivery problem. Check your carb "O" ring that seals the carb to the intake tube...make sure it is there and sealing. If you don't find a prob there, go to a welding supply shop and ask for a set of tip cleaners....runs less than $5.00. Use them to clean out each and every passage in the carb. You may need to soak the carb in a can of chemdip or similar carb cleaner. Remove all rubber parts before soaking the carb in it. The carb you have doesn't have a diaphragm, otherwise, that would be the thing to replace.

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