Hi 4 hp B&s engine on a merry tiller rotavator seems to pressurize the fuel tank at high revs so fuel squirts out through the cap vents - any idea why. The engine "Hunts" a bit if thats the term - sort of revs a bit/wont idle stay at constant revs sometimes
A leaky valve would not pressurise the fuel tank. In theory, a ruptured pump diaphragm could. Replace it (under small cover on side of inlet manifold - costs pennies, taked 10 mins).
phil_saunders@bigfoot.com
Phil Saunders, March 2009
Check the muffler for blockage.eg wasp nest or carbon buildup. If this is ok I would suggest a burnt out valve or riding (not closing) exhaust valve. If it is also hard to start, the valves could well be the problem.
