Briggs & Stratton 550 series engine won't idle


Old 05-27-12, 09:23 AM
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Join Date: May 2012
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Briggs & Stratton 550 series engine won't idle

I have a Bolens mower with a Briggs and Stratton 550 series (10T802-0547-B2) engine - at the end of last season the engine was running really rough so I replaced the blade, oil, spark plug, fuel, air filter, and diaphragm. I also cleaned out the carb and fuel tank.

The engine is now running a little too great - it now seems like it doesn't want to idle. If I take the governor spring off the governor hunts and sometimes stabilizes (until I attempt to move the mower), but with the spring on it just seems like the governor doesn't have the force to overcome the tension.

I will also say that prior to the beginning of this season I had never emptied the fuel tank out between seasons, and even after cleaning out the carb/fuel tank there still appears to be some sediment in the carb.

I'm at my wits end with this - I can try cleaning the carb/tank again, but I wonder where the sediment is coming from (I made sure all tubes/connecting surfaces were clean before putting it all back together). I also wonder if that is enough to cause the problem I'm experiencing.

Does anyone have any thoughts/suggestions for me?

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Old 05-27-12, 10:30 AM
cheese's Avatar
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Did you take out the main jet and clean it?
Old 05-27-12, 01:47 PM
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Location: St. Louis
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You need to install a new diaphram kit, it is Briggs part # 795083 or old # 495770 also Lowe's has a kit #5083 which has the same parts.
Here we go:

Remove air cleaner, there are 2 bolts that hold things together, one on the front of the tank 3/8" and one into the block 1/2", remove these bolts, now "slowly" slide the carb/tank off the intake tube and breather tube, now tilt the tank in to release the throttle linkage and waalaa the carb/tank is removed. Check the intake tube to see if the O ring seal and plastic retainer are still on the intake tube, if so remove them and re-install them into the carb. Remove the 5 screws from the carb/tank remove carb(don't loose the spring) now spray all holes, cracks and crevases in both the carb and tank surface with brake parts cleaner, remove the main screen(looks like a thimble), now with a small screwdriver pry out the main jet(carefully) and clean it, check the O ring on the main jet for damage, if it is damaged it must be replaced, reinstall the jet, it can be difficult some times to get it to snap back in place(I use the rounded end of a screwdriver handle). Remove and clean the fuel pickup stem(not necessary if the fuel tank was clean). Clean any junk/rust from the tank. Install the diaphram on the tank then the gasket(no goo or sealer) now carefully replace the carb(the spring will try to misalign the diaphram), tighten all screws a little at a time so as not to crimp the diaphram until they are all tight. Install the carb/tank in reverse order and you are done. If I missed something one of the real mechanics will correct me. Have a good one. Geo
Old 05-28-12, 12:23 PM
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Join Date: May 2012
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Did you take out the main jet and clean it?
No, just sprayed out the carb with cleaner. Would that cause this problem?
Old 05-28-12, 01:18 PM
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If I missed something one of the real mechanics will correct me. Have a good one. Geo
A "real" mechanic just gave a very detailed account of how to do the repair

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