I have a 6hp Briggs, flathead type engine, about 7 years old. The engine runs well, but is difficult to start. I replaced the carburetor with a brand new one, and also replaced the primer bulb. It starts and runs perfectly if I squirt some gas in the intake. I then checked the primer bulb and noticed that it does not force gas into the intake. If I put a little air pressure in the primer circuit hole in the outside flange of the carburetor, it sprays fuel into the intake, and so the problem is in the primer bulb operation. I can't see anything wrong with the primer bulb, its mounting, gasket, or the plastic intake/air cleaner plate that holds the primer bulb. I can only think that somehow the primer bulb is not generating pressure when pushing it. Any suggestions?
Briggs 6 hp lawnmower engine
- Thread starter wrede
- Start date
955Lincoln
Gold Member
It has been a while since I have worked on small engines and I'm having trouble visualizing where in the fuel circuit the primer is located. The old ones I remember were part of the carb. That being said, are you sure that you have good fuel flow out of the gas tank? Can you take a line off and see if the fuel flows well? Clogged screen in the tank or stopped up vent hole in the tank cap.
The primer most likely has check balls and springs so when you push on it fuel will be forced into the carb and when you let off it should suck fuel from the tank into the primer.
The primer most likely has check balls and springs so when you push on it fuel will be forced into the carb and when you let off it should suck fuel from the tank into the primer.
RandyT
Elite Member
Does this one have the rectangular air filter. If so the gasket behind the air filter mounting plate isn't sealing against the carb. You can try tightening the cover down a little more or double gasket the air filter mounting plate.
Yes, it's the rectangular filter. I have tightened the three bolts, two of them that attach to the carb inlet. I can't tighten those any more without stripping them, but I see from your suggestion that maybe the plastic filter holder, the part toward the carb, is warped somehow and so the gasket doesn't really seal the primer air channel. Or maybe I'm tightening it too much and causing it too warp??? I'll have a look at that and either try two gaskets or a little Permatex. Thanks for the lead.
RandyT
Elite Member
I see this problem 3-4 times a year in my lawnmower repair business