My mower with the B&S 6.5 HP stopped suddenly after a routine hour of mowing, and now will only start for 1 second before shutting off. Oil, gas, spak plug and air filter are good. Have let it sit for a few days and put in fresh gas but same thing. I have maintained it and it has worked perfectly for 5 years.

It will not start for more than one second with the primer bulb pushed in, or if I prime it 3 times or 40 times.

Anyone have a similar situation?

BX1, September 2009

Also check the bowl bolt. The jets feed through the center of this bolt, there is a tiny hole in the center, that feed from two more holes near the base of the bolt head. I'm having a similar issue at this time and just found that hole was plugged. I used a small jet drill to clear it. Here's hoping.........

Ozzie, October 2009

The brass jet on the bottom center of the carburator float bowl has become clogged with sediment. when you take it off a bread tie wire & come carburator cleaner are all you need to clean the jet. Take care when putting on the bowl as the sealing gasket (large o-ring) must seal perfectly otherwise the primer bulb will squirt fuel out of the bowl instead of priming the carb venturi. a 5/16", 3/8" & a 1/2" socket (& ratchet) carburator cleaner & bread tie or garbage bag tie wire are all you need to complete the repair. It helps if you drain the gas tank before you begin. Or you can just pinch off the line with a vice grip. Quantum engines are some of the best & are one of my personal favorites. Good luck !

Jimbosjunkpile (youtube screen name), September 2009

Quantum engines don't have diaphragms......

Dran the float bowl - it's possible that a drop of water has found it's way in, blocking the jet. While the bowl is off, check that there is a decent flow of fuel.

These engines are prone to breaking the inlet pipe that runs across the top of the cylinder from the carb to the inlet port. This will cause similar symptoms of it is cracked.

phil_saunders(a)bigfoot.com

Phil Saunders, September 2009

Replace the gasket that separates the carburettor from the fuel tank...its in 2 parts - the diaphragm part fits next to the tank, the gasket bit is on the carb side.

John, September 2009