Briggs 3.75 motor
 

I have a Briggs on a MTD mower about 2 years. When you start it it runs
like the choke is on. It has the little primer bulb. It is running way
to rich but there is no adjustment on the carb. In fact the carb is more
or less sealed. I have put in fresh gas and changed the plug. Any ideas?


From Mel & Donnie in Bluebird Valley

if its the kind of engine that has the gas tank bolted to the bottom of
the carb, the the rubber gasket between the tank and carb needs to be
replaced,. its called a carb diaphram.ive fixed many doing what yours is
doing .youll need the engine model and spec number stamped on the
sheetmetal covering the top of the motor to get it or just take the old
gasket with you to match up..lucas

I took it apart and seen the rubber gasket you are talking about, I
cleaned it and put it back together and it is running good now. Must
have been a speck of dirt somewhere - THANKS - If it does it again I
will get a kit.


From Mel & Donnie in Bluebird Valley

that rubber gasket isnt just a gasket, it pumps fuel.if it get
stretched or distorted it acts up,pumps to much or pumps to little.
lucas

I had the problem of slow running, "hunting" and running as if the choke was permanently on with my Briggs Stratton 375 lawnmower engine. This fix is great and solved my problem immediately. It now runs as new. I did not have spare gaskets but cleaned up the existing ones which appeared undamaged but I will now get spares in case the problem re-occurs.
Thanks for such useful advice

Briggs & Stratton Carburetor Diaphragm Kit - Lawnmower World