I have a MTD rider with a 14.5 B&S engine. When I mow downhill, or when the left side is lower than the right the engine slows and sometimes backfires. It runs okay on level ground or tilted lower on the right side. What causes this? Just sprayed carb abd put on new fuel filter. Didn't stop problem.

In the carb is a needle and seat valve that works off the bowls float. This is where I would start. Just spraying the carb or even the bowl and float sometimes isn't enough.

Remove fuel line and spray the seat valve and needle valve that goes in the seat.

Your problems leads all to not enough gas in the carb bowl and when it leans the carb is starving for more fuel

If seat and needle valve are working correctly and the float is set properly and free to work it should be fine. If not then a weak fuel pump may be an issue

If I had your engines

Model
Type
Code
I may be able to get you the factory specs on the carb adjustments.

Thanks 21. I will try your advice and hope it works. With 2 in college and cut pay and hours I cannot afford to pay for pro repair so I especially appreciate your help.

Model 287707
Type 1210-E-1
0008029ZD

I found your manual for that engine and you can check/adujust the carb adjustments in needed.

Also I'm adding the "parts" list manual to cross reference the location of adjustments and the blowout to know what's what.

http://www.briggsandstratton.com/maint_repair/manual_and_more/docdetails.aspx?showpdf=275038_-_LO.pdf

http://www.briggsandstratton.com/maint_repair/manual_and_more/docdetails.aspx?showpdf=MS2719_LO.pdf

Part #105 is your gas needle and part # 106 is the needle seat. #387 is the fuel pump.

Those three items plus the float is basically the whole fuel in bowl to run engine.

You can get kits for the carb. This is a DIY project. Let me know how it goes.

Thank you very much.