My lawn mower is surging and spark plug is black is this lack of air briggs& stratton . plus runs ok when running out of petrol /????

SOURCE: My lawn mower briggs & stratton engine 650 series will not start

check the fly wheel and coil it may have rust on it if so sand it off

SOURCE: Briggs and stratton engine surges and slows, repeatedly

There is still either water or debree contaminating the fuel system. Surging is usually debree, empty and flush the tank with gas or Iso alcohol, disassemble carb soak in solvent for 30 minutes blow out the carb passages, reassemble and if the problem persists run engine at top rpm with air cleaner off and block off carb intake with hand, this will stall the motor restart and repeat 4 - 5 times this wiil draw out any debree or other blockage in the carb.

SOURCE: Briggs & Stratton 4.5 hp running rough...too much fuel

Hi did you squeze excess oil from filter so it can **** air in??

SOURCE: Briggs & Stratton Quattro lawn mower

computerscot is right. This engine is not designed to run slower than a few hundred RPM below maximum. The carb has a built-in fuel pump that only operates properly at relatively high speed. Your motor probably has either missing or weak throttle springs which will lower the RPM. Replace them and adjust the tension so that the speed is up. For a diagram of the carb and springs, check the Briggs & Stratton online user manual maintenence section. Look for file "briggsandstrattonMS5373-GB.pdf".

SOURCE: Briggs & Stratton Modle# 100000 will not stay started.

your engine is only running on the fuel you are pumping in, the carb. is not lifting the fuel on its own, maybe because of water in the bowl or dirty jets. You must take the bowl of and clean it out and depending on the type of carb. it might need a new diaphragm. Stephen.

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