Briggs 3hp Carb (397939) running rough..help..

[ILENGINE]

this may or may not be relevant. Do you have a way to do a compression test. I am wondering if this issue may be more compression related, then carb related. Low compression causing improper ignition of fuel in the cylinder. those small L head briggs engines were bad to float the intake valve.

 

[jsm0960]

Could anyone help me with a carb problem...I have a Briggs 3hp on a Mclane edger. Carb part no. 397939. It has not ran smooth since I purchased it used. I have taken it apart and soaked in carb cleaner, blown out with compressor, put a new kit on (twice) and adjusted mixture screw. First, it is hard to get started. Most of the time I need starter fluid to get going. After warmed up, it cranks fine but runs very rough. It surges and sounds like it wants to cut off. Runs like there may be trash in it but I have cleaned it twice along with the soaking. Or either the mix id off which I have played with for quite a while. Is there anything else I can look at when I take it back off? Thanks

Have you done a compression test on it?

 

[Rivets]

Sorry I forgot the manual.

http://dl.dropboxusercontent.com/u/12502267/B&S Service Manuals/01_270962SingleCylinderLHead.pdf

 

[tomsteve]

along with what others have said about compression and carbon build up, spray some carb cleaner around the gaskets while running and see if it smooths out. it could be a gasket leak,too.

 

[hatteras451]

I had a 2 Hp that the head was FULL of carbon and it ran poorly until I cleaned it out. It had the same carb.

Thanks for the suggestion!..I may have to look into checking that...

 

[hatteras451]

along with what others have said about compression and carbon build up, spray some carb cleaner around the gaskets while running and see if it smooths out. it could be a gasket leak,too.

I have replaced the gasket twice. I did have an issue with fuel leaking around one side on the previous gasket. Do you think it would be fine to try 2 gaskets? Thanks..

 

[hatteras451]

Sorry I forgot the manual.

http://dl.dropboxusercontent.com/u/12502267/B&S Service Manuals/01_270962SingleCylinderLHead.pdf

Thanks for the manual breakdown!...I am going to disassemble it again and make sure everything is in place and clean...once again...

 

[Fish]

Is there any chance you can give all of the model/type/code numbers, which are almost readable in your pic?

 

[Fish]

Before all of my "haters" start pile driving me, I just would like to know what the date code was, so I could know whether or not you need to change your point ignition over to electronic.......

 

[Fish]

While still waiting for the model/type/code numbers, another problem with these engines had, when the carb is removed, the carb has/had a downspout/pipe into the tank near the bottom, and many of the tanks had a small cup/bowl up where the carb bolted
on, and the bowl served as a normal carb bowl. But after a few decades of sitting with old fuel/water, this small cup/bowl gets
rusted up, and develops rust pin holes in the cup, and the gas seeps back into the tank, and after a while makes it real hard to start, as it gets the startup gas from this bowl. Also, if the leak is bad enough, will affect the running of the engine.

But as I said earlier, we need to know which model you have.