View Full Version : Briggs & Stratton 4HP engine running rough

08-08-2010, 05:44 PM
Engine (on a Murray mower) starts and runs, but smokes and runs very rough. I think the fuel mixture is too rich because the engine runs perfectly just before it runs out of gas in the tank, but I can't find any way to adjust carb. I have changed spark plug, the gas vent cap hole is clear, and the engine runs the same when the air cleaner is off.

Any suggestions on what the problem might be and how to fix it would be appreciated. This mower is a few years old, but has not been used much. It used to run fine. I don't know if it is related to the current problem, but the problem seemed to start right after an oil change.

The engine codes are:
Model: 10A902
Type: 2291 B1
Code 99102554

Thanks for any help anyone can provide.

08-08-2010, 07:55 PM
Remove the two bolts that retain the tank and carb. Carefully pull the carb and tank off the crossover tube then tilt the tank and carb to allow the governor linkage to slip out of the throttle shaft. Remove the 5 screws that retain the carb to the tank. Clean everything up and replace the diagphram and gasket(part #395770) noting order of replacement. Remove the pick up screen from the carb and clean it with carb choke cleaner, at the same time spraying up through the pick up as well. Reassemble and you should be good to go. For me, I find the diagphrams will last about 2-3 years.

08-08-2010, 09:04 PM
Hey Dutch !

Did you copy/paste that from one of my post ???

Let's hear less of your Ole age around here, You still have it.....That's some very good de-structions. Haha ! Thumbs Up

08-08-2010, 09:13 PM
Sorry, Restro, at 72 I'm to old school to look around for something to cut and paste--at least not this time!!!

If I type destructions long enough I can even get in an argument with myself.

08-15-2010, 12:49 AM
The new diaphram was just what was needed. Replaced it today and engine runs great. Thanks Dutch1 for taking the time to help and for the great instructions. By the way, the part number for my mower was 795083.

08-15-2010, 09:08 AM

Part number 795083 is the latest superceded number for 495770, which has been the proper number for as far back as I can remember. Unfortunately 495770 occupies a spot in a memory chip in my small brain and I have been unable to replace it with the new one!!!!!

Glad I could help.