My old lawn mower (almost 20 years) is a craftsman with a 5.5 hp Briggs and Stratton. It has always run great and still does except now it dies halfway through the lawn. It starts fine cold. No indication that it's about to die it just quits running. To get it going again I have to pump the primer 7-8 times and pull cord as many times and then it runs fine again for awhile. Where do I start?

PM Pat Fundine. Don't tell him I said this but he is a small engine genius.

Wild guess....make sure gas tank vent is open.

Sounds like rings to me

Loosing compression when it gets warm . Is it worth replacing the jug and rings on it ??

Sounds like your atmospheric relief valve has expired.

It was used too much when it was new.
Or, cracked fuel line that might be sucking air.

The diaphragm in the carburetor that pumps fuel. Easy fix.

Carburetor.
Seen it a lot. With that age (20 years) varnish and gunk will build up over time. Today's crappy gasoline doesn't help too.
Clean the carburetor out , if needed rebuild it.

I'd just replace the carb. They're not very expensive. That and a standard tube up....replace the plug, air filter, fuel filter if it has one. If it doesn't have one, get a generic small engine fuel filter and install it.

Imulsion tube is plugged or has dirt floating around in the carb bowl, it plugs the tube. No gas, no vroom vroom.




And 160 user is wrong..... I'm actually a magician..... I was titled that last week by 2 different long term customers.


I dont mean to be a jerk, but there's at least 5 answers above me that aren't even parts on that push mower.

First thing I would check is the coil. As soon as it stops running, if you have one put a spark tester on it and check for spark. If present then start checking for fuel problems. If no spark you have a coil that is breaking down when hot.

this^ is the first and easiest thing to start with

Or, you can buy a brand new Predator (Honda clone) engine at Harbor Freight for $100.

I do small engine/farm equip repair on the side. Seen this many times. It's a fuel problem. Idk what your carb type is. If it is a flo jet (bowl type) remove the bolt that holds the bowl on. Clean out the carb and bowl good with spray carb cleaner. Especially the bolt, it's ported, and the main jet which goes up to the throat of the carb. If it's a pulsa prime, (diaphragm) I suggest a kit and a good cleanout. IMO avoid cheap knockoff carbs found online, buy enough and sooner or later you'll get a junker.

This same problem has happened to my old B&S thrice.

First time the problem was a fuel tank vent that wasn't allowing air to come in.

Second and third times it was a clogged fuel filter.

Could be a lot of things. But I would definitely check these things when trying to diagnose the problem.

Go get a new one. Worn out . You got the good out of it. Use that TRUMP money you been holing up !!!!!!!!!!!!!!!!!!!!!

I knew you would throw out some technical jargon!

You want technical now...


Imulsion tube is plugged by green ethanol flakes. The engine will not run without gas. When you push the primer a few times it will break the suction on the tube from the flake of gunk. The engine now has the ability to draw gas up the imulsion tube and start. A few minutes later the flake of ethanol will get sucked up again and cut the fuel.


Most push mowers do nat have, fuel pumps - gravity feed. No jugs. Compression isn't really an issue in 4 cycle, it's more about leak down tests and valve adjustments- it wouldn't even start if those were bad. It doesn't have an electrical issue at all - it starts hot when you push the primer bulb releasing the pressure.

patfundine = majician and scholar