Why does a Briggs and Stratton 4.5 HP lawn mower engine stop one minute after it starts?

Answer 1

Had the same problem. Solved it by electronic ignition that cost me 40.00 Eliminates all B.S.It Could Be Fuel Starvation

The problem you describe sounds like it could be fuel starvation. I would suggest checking the carburetor, fuel filter (if it has one), and all the fuel lines. Another possibility would be the air filter, but I'd check the fuel system first. Good luck.

• I had a similar problem with my Briggs and Stratton 4.5 HP engine. There is a ceramic or plastic duct that looks to provide fuel / air flow from the carb to the combustion chamber. Mine was split near the point that it entered the combustion chamber. If the engine can't get fuel, it isn't going to fire. No idea how I'm going to fix this. I'm currently in the process of looking for a replacement part without much luck. Given the low cost / seemingly poor design of this engine, I might just by a different model that isn't prone to this problem.
• To the person having trouble finding the replacement part for the "ceramic or plastic duct" that provides fuel/air flow from the carb to the combustion chamber: You can repair the one you have, at least temporarily, using JB Weld. I'm not a spokesman for the company, it's just that I've used it on several parts when new parts were hard to find. JB Weld is an epoxy. Just clean and dry the area of the crack, making sure that no solvent, grease, or dirt is in the crack; thoroughly mix equal amounts of resin and hardener; let it stand until it becomes tacky; work it into the crack with a toothpick, match stem, or a piece of popsicle stick small enough to fit where you need it; then smooth it over so the JB Weld extends a little ways past the crack and allow to set for 24 hours. JB Weld is impervious to gasoline and oil after it has set.

More answers from FAQ Farmers:

• The carburetor and the fuel lines are good. Priming the bulb works for a minute, and that must be done everytime to start the mower. It cannot start if it stops and the bulb is not primed again. It could start fine last year with the air filter off, so the air filter is not the problem.

• This is most definitely a carburetor problem. I've seen this many times while working in small engine service. You'll need some carburetor cleaner and some compressed air (a compressor with an air nozzle fitting). Remove the air filter and spray the carb cleaner directly into the carb throat. You'll also notice a primer venturi hole and possibly a secondary venturi. Spray the cleaner into them directly. Allow to sit of 5 or 10 minutes then blow out the venturi with the compressed air. It may also be necessary (for a gravity feed carb) to remove the float bowl and spray cleaner into the main feed tube. Blow this out with the compressed air also. Reassemble and start the mower. If you were able to blow out the venturi obstructions, the mower should now run fine.

* The "venturi holes" are very small...but you can get to them without having to remove the carburetor and it might solve your problem. I've had luck running a very fine wire through them to clean them out. A bread tie that has had the plastic removed is perfect...

I have Just spent 2 days working on a darn Briggs 4.5 push mower. It was Brand New, Never Used! Had the same problem as you say and will see mentiones repeatedly on line chat rooms. Well, I solved the problem and mine is running GREAT, Starting with one Pull, without even Priming it, if it's warm. Here's the deal. Everyone was on the right track, Fuel starvation, carb problem etc....Well, I took the carb off and foynd that the Fuel intake tube, On This NEW Carb, had a thick layer of very fine mesh wrapped around it. I held it up to the sun and barely seen daylight, it looked l;Ike Duct Tape! I removed it and seen that the filler tube did in fact have it's own screen filter as well, underneath this grey mesh crap. Well i then proceeded to blow out every port hole with compressed air and replaced everything, except that grey mesh wrap on the filler tube. I didn't even prime it, and it atarted up with one pull and has been running great ever since! With so many guys having this problem with this engine, I believe that was the problem. Good Luck Dan O'

My friend asked me to take a look at his Craftsman push mower with Briggs and Stratton 4.5 HP engine with above symptoms. He says the mower is 2 years old.

Upon disassembly found restricted screens and filters as described above....On this one, it is clogged with gunk from the inside of the fuel tank rusting out. Am now in the process of pouring boiling water in rusted tank to try and get most of the rust out, and will recommend to my friend to contact Briggs and ask about the availability of a coutermeasure tank that won't rust. I own a McLane front throw reel mower that is 17 years old, and the inside of the fuel tank is silver, shiny, and not a speck of rust inside.

Will re post after I get this reassemebled and update.

Update to above...After cleaning rust and scale from filter and pickup screen, and cleaning out fuel tank best as possible....mower runs like new. Briggs and Stratton site recommends draining tank or putting in additive in tank when storing to prevent scale and rust, but I have never had to do that with my McLane. My opinion is they should make a better tank impervious to rust and scale. I will recommend a replacement tank to my friend. Hope this helps someone.