Lawnmower running rough

[modelageek]

Need to know what kind of carb it has. Earlier b&s had the carb mounted on the tank,)these had a habit of diaphrams going bad. Then they went to a normal carb with a float and bowl, there's a tiny hole inthe brass tube that tends to get plugged. The newer ones have plastic carbs, i've not figured them out yet. They all have an auto throttle rod that needs to be correctly adjusted.

I posted a picture in post #13 the carb was screwed onto the tank and i took it off and placed it next to the tank in the picture. there is a "rubber diaphragm" that sits on top of the tank......is that the diaphragm you are talking about?

 

[Froggmann]

What you have is a pulsa-prime carburetor that mounts to the fuel tank. There is no choke, float, or adjustment screws on the carburetor. The spring you see is a governor spring, some have 2, one for governed idle and one for hi-speed control.

Replace that diaphragm, part #795083. Make sure the air filter is properly oiled as well.

If the diaphragm replacement doesn't cure the problem, replace the carburetor, they are only about $25 and come with a new diaphragm.

 

[modelageek]

What you have is a pulsa-prime carburetor that mounts to the fuel tank. There is no choke, float, or adjustment screws on the carburetor. The spring you see is a governor spring, some have 2, one for governed idle and one for hi-speed control.

Replace that diaphragm, part #795083. Make sure the air filter is properly oiled as well.

If the diaphragm replacement doesn't cure the problem, replace the carburetor, they are only about $25 and come with a new diaphragm.

thanks for the info.....any idea what the carb part # is or how i find it?
*thanks again for IDing the type of carb........I found this on youtube. I will try the diaphragm replacement and also look for a warped carb http://www.youtube.com/watch?v=LzpSy5CJL6k

 

[martin]

The diaphrams are available from many places and are cheap, the fuel pickup tubes are sometimes a problem on those also. Keep us posted on what happens. I couldn't get the pictures before due to circumstances beyond my control and was using my e-reader on Mcdonalds wifi.

 

[dankhimself]

here is a picture the carb is sitting next to the gas tank.......I have since put it back together(took 7 minutes) and it started right up......it might have been running a little better but I am not sure....I think I have a different setup then what you guys are talking about.....on the fuel tank there are 6 screw holes. actually there are only 5 screws. the middle bottom one lines up exactly at the middle of the carb bowl........it has threads in it as if something should go there but as far as i can tell nothing was there....I don't know where this jet needle thing is
*I just looked though a Haynes small engine manual I had.......I think I have a non float vacu-jet carb

My mistake, from what I read it seemed different, and my computer wouldn't show the photo posted. Good luck with it dude.

Sent from my DROIDX using Tapatalk 2

 

[modelageek]

I bought the diaphragm at a local shop for $4.....took it apart and cleaned it up....there was a slight warp on the bottom of the carb but I think it is OK........I put it all back and it runs much better...there is still and occasional slight hiccup but i say it is at 90%.....one thing i did notice is that if I spray carb cleaner around the intake tube where the carb meets then the idle changes and will stall if i keep spraying..I am not sure if it is leaking through the intake or where the carb meets the fuel tank..I pulled it off and put some grease (not sure if this will hurt down the road) and it is a little better. .... I wonder if I need a new o-ring on the tube......I am pretty sure i fit the o-ring and then the plastic piece that holds it on correctly......thoughts?

 

[modelageek]

I just went out and sprayed carb cleaner all around the intake tube and the base of the carb.....did not notice any idle change....I think the high temp grease helped......I am not sure if it will hurt the engine at all..........I probably will get a new oring when i can

 

[94 lngbd]

thanks for the info.....any idea what the carb part # is or how i find it?
*thanks again for IDing the type of carb........I found this on youtube. I will try the diaphragm replacement and also look for a warped carb http://www.youtube.com/watch?v=LzpSy5CJL6k

In that video the guy is f*cking crazy, did any one notice he's pointing directly at the fuel tank & at times he's actaully touching the cap or tank & he has a smoking cigerette in his hand as well

 

[cvar]

Go search within http://www.mytractorforum.com for ideas.

The two that immediately come to mind are "coil gap" and "flywheel key". The ignition coil is powered by the flywheel magnet, so the air gap between them is rather finicky (a business card makes a good gap gauge). The flywheel shaft has a small woodruff key that can sheer off, which means your flywheel is no longer aligned with pistons, so spark timing is off. If it's off by a lot, it'll also backfire.

 

[modelageek]

Go search within http://www.mytractorforum.com for ideas.

The two that immediately come to mind are "coil gap" and "flywheel key". The ignition coil is powered by the flywheel magnet, so the air gap between them is rather finicky (a business card makes a good gap gauge). The flywheel shaft has a small woodruff key that can sheer off, which means your flywheel is no longer aligned with pistons, so spark timing is off. If it's off by a lot, it'll also backfire.

thanks for the info.......it is running pretty good now with the new diaphragm and plug.

 

[Will]

All seasonal engines are vulnerable to carb problems. I have lots of old Briggs and Stratton engines. They can be converted to CD ignition which helps a lot, but you need to use fuel stabilizer or drain the tank for the winter.