Oil & Fuel Briggs & Stratton fuel issues

[Retrorod]

Firstly I'd like to support a proposal I have seen here that there should be a dedicated forum for these engines. God knows, there are enough of them around installed in endless mower brands.

I have a 13.5hp B&S in a ride on mower that has been sitting for a time waiting for a new transaxle. The engine was running OK when put away.

Now, a perculiarity of this engine, when in previous good running order, was that when about to run out of fuel, it would surge madly as the govenor sought to manage the lean mixture. Sometimes it made it back to the shed, sometimes not. This habit is relative to this problem that has appeared after sitting around for awhile.

When started once again, with fresh fuel, it immediately started surging, with the govenor working overtime to keep it going of a sorts. I immediately stripped fuel lines and carby. Some rubbish in the tap appeared to be the culprit. However, with a new line straight from tank to carby, and the Nikki carby cleaned by every method known to mankind, there has been absolutely no improvement. The govenor setting checks out OK, and I am convinced the carby is running lean for some reason as a little choke allows the engine to run smoothly enough.

There is something I'm overlooking here I know, but what? I have noticed the Nikki float needle has no specific seat, nor am I clear about setting the float level. In any case the the thing does not flood, something one might expect if needle and seat were not working.

If someone has experienced something similar, and fixed the problem, I'd like to hear from you. RR

 

[tcartwri]

How's the muffler.

 

[The Fred]

Definitely a lean condition. You might have missed a jet. An easy way to tell is take a propane torch (small one) and get the machine running then open the propane valve on the UNLIT torch pointing in the intake. If it runs better it is lean.

Post the model and series maybe we can find a breakdown online.

Most likely it is in the low speed or transitional circuit.

http://outdoorpowerinfo.com/repairs/briggs_intek_single_ohv_nikki_carb.asp



Fred

 

[eddie48]

I have to agree with Fred. Did you run a wire through all of the little holes in the carb? Sitting for a while will often gum up one of them and they don't clean easily. The other possibility is that there is an air leak in one of the carb mounting gaskets or intake gaskets.

 

[Gator6x4]

For what you have posted I assume the carburetor is one of the no adjusting type with the adjusting needle sealed. If this assumption is correct you need to obtain a diagram of the carburetor, carefully remove the cap covering the fuel flow adjustment needle. Adjust the carburetor (be very careful, a one eight inch movement of the needle will really increase fuel flow) and replace the cap.