craftsman 6.75 torque engine surging.

Joined
Mar 12, 2007
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canada
Just bought a used craftsman mower in really good shape. mower has sat for the last three years,being used only a couple of times,paint is still shiny under the deck. The problem is the mower starts fine but has a slight surge that won"t go away. I put a new plug in changed the oil, air filter, sprayed the carb with cleaner,fresh gas and cheap walmart gas treatment, all to no avail, still has the slight surge. Any suggestions? Are these 6.75 engines any good? Thanks
 
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Joined
Sep 5, 2007
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903
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wa state
mine does the same thing for the 1st 20 or so seconds after starting it. I replaced the governer spring and it helped to make the surging less.
 
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Feb 21, 2004
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USA
Disconnect the fuel line and see if fuel isn't partially plugged. It's a good idea to have a fuel filter on these small engines. If it isn't the fuel I'd clean out the carb bowl. Water in the carb bowl can cause surges.
 

hemitom

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well i took the carb off, checked the needle and seat,float all looked good soaked all the jets and inside with carb cleaner, blew it all out with air, didn't notice any gunk or varnish inside. Put it all back together still has slight surge. Also the gasket where the primer housing bolts to the carb is split, would this cause the primer bulb not to function , when you prime you get nothing.
 

hemitom

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yes has a carb bowl, needle and seat, float looked good, also no adjustment screws on this carb.
 
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Jul 20, 2008
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1. Partial Blockage of Main Jet. This is for bowl type carburetors only. Stop the fuel flow to the carburetor, either turn off the fuel valve or pinch off the line with a pair of fuel line pinch off pliers or a pair of vice grips. With a pan suitable of containing gasoline, loosen the fuel bowl nut and catch the gas. Now remove the bowl nut and the bowl. Blow out the holes in the nut with compressed air or carburetor cleaner. Some Tecumseh carburetors have a tall bowl nut. Some will have a pin hole in the side of the nut, and some will have a pin hole just above the bottom set of threads. This hole must be clear in order for the engine to run properly. For engines that do not have the jet made in the bowl nut (Kohler, Kawasaki, Honda, some Briggs and Strattons, Onan, Wisconsin-Robin) the jet is attatched to the center post of the carburetor. Some are cast in and others are screwed in. Blow this hole out and blow up the center post to clean the main nozzle. Use compressed air or carburetor cleaner. For all down draft Briggs and Stratton Flo-Jet carburetors (7, 8, 10, 11 HP Horizontal), remove the bowl nut (has adjusting needle in it) and blow compressed air up the nozzle. For Opposed Twin engines, Horizontal and Vertical, remove the bowl drain nut and blow air in that hole. 2. Leaking Intake Gasket. Check for a loose carburetor or mainfold connection at the block. All Briggs and Stratton engine 3 to 6.5 HP, check the intake manifold for cracking (may have to remove carburetor) or loose connection at the block. You will need to remove the air shroud to get access to the intake manifold.
 

hemitom

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Mar 12, 2007
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Well replaced the gasket that mates the primer housing to the carb now the primer works, I added some techron to the gas and let it run for twenty minutes then set overnight. This afternoon i pulled the float bowl off and there was a lot of yellow particules in the bottom of the bowl, sprayed the carb with cleaner again cleaned all the jets and ports with a plastic wire blew it out with compressed air, it runs much better but still has a slight pop or missing sound.
 
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