Small Engines (Lawn Mowers, etc.): surging Murry 4.5 B&S, briggs stratton engine, briggs stratton

Question
Hi Allen,

I'd like to thank you in advance for any help you might offer.

I have a 3-4 year old Murray rear discharge push mower with a 4.5 hp Briggs & Stratton engine.

It started surging very badly after 2 years continuous good use. It uses a much greater amount of fuel when surging; then all of a sudden speeds up to normal speed and runs fine for about 2 minutes; and then abruptly dies - out of gas.

I had a local small engine fella repair it for $40. He told me it was the diaphram in the carb and that he replaced it. The trouble is, the repair only held for one season - about 5 months.

Now it is surging badly again. I hate to spend $40 every year if it's something I can do myself. I am fairly handy and have a full set of tools. I have successfully rebuilt automotive carbs in past years. But oddly, these small simple B & S carbs have me a bit baffled. Can you offer me any help:

1) Does it sound like the diaphram?
2) Is this easy to fix?
3) Where can I get a rebuild kit - or a diaphram?

Thanks and best regards,

~Bill


Answer
Hiya Bill- could be the diaphram, and about any small engine repair shop can get the carb rebuild kit (they're even on EBAY).  Your problem sounds like the carb is sucking air from somewhere it shouldn't, leaning out your mixture- causing surging and ultimately causing the engine to quit.  This could be a faulty gasket between the carb and intake, loose carb attachment bolts, clogged fuel intake (debris in the tank) could even be a bad gas tank cap (they have to breath, or the tank develops a vacuum and fuel flow ceases) Its a relatively easy breakdown for a mechanically inclined person, just bring a notepad to note arrangement of springs and rods, linkages and a dose of patience.  TIP- wrap rods and links with a piece of masking tape and write A- B - C etc on it to help identify them on your notepad later (trust me- you CANNOT overdocument linkage location and hookup points ha )Let me know how it goes- you can do it !