lawnmower problem

[ghostrider]

any small engine experts here?

I have a 6yr old Craftsman mower (Briggs & Stratton 6.5hp engine) that has been working fine until 1 week ago.

It starts fine, but it won't stay running. A new spark plug and air filter made no difference. I've drained the gas, put fresh gas in, checked the fuel line to make sure gas is getting through.

As long as I pump the primer bulb several times it starts right up on the first pull, but it soon stops running (within a couple of seconds) like its starved for gas.

The mower does not leak or burn oil and the motor oil level is fine.

The only thing I can figure is something clogging the carb. I am going to try some Seafoam or carb cleaner, but short of disassembling the carb I'm not sure what else to look at.

any ideas?

[74novaman]

If it is like mine, is the throttle controlled by a cable attached to the handle on the "push" part? Perhaps it is stretched out or loose. No throttle from the cable, no running. Just a random thought.

[ghostrider]

If it is like mine, is the throttle controlled by a cable attached to the handle on the "push" part? Perhaps it is stretched out or loose. No throttle from the cable, no running. Just a random thought.

It doesn't have a throttle - there's only 2 speeds: on and off.

However, I am wondering if the safety lever cable has stretched; there's a lever you have to hold down to keep the engine running. If figured it was fine since it starts, but I may look at that again since I never thought about it stretching.

thanks.

[74novaman]

If it is like mine, is the throttle controlled by a cable attached to the handle on the "push" part? Perhaps it is stretched out or loose. No throttle from the cable, no running. Just a random thought.

It doesn't have a throttle - there's only 2 speeds: on and off.

However, I am wondering if the safety lever cable has stretched; there's a lever you have to hold down to keep the engine running. If figured it was fine since it starts, but I may look at that again since I never thought about it stretching.

thanks.

Well, I wasn't being clear, but that little safety lever was what I was talking about. Guess I'm just not good at using the correct terms.

I use this tool dictionary:

HAMMER:
Originally employed as a weapon of war, the hammer nowadays is used as a kind of divining rod to locate expensive parts not far from the object we are trying to hit.

MECHANIC'S KNIFE:
Used to open and slice through the contents of cardboard cartons delivered to your front door; works particularly well on boxes containing seats and motorcycle jackets.

ELECTRIC HAND DRILL:
Normally used for spinning steel Pop rivets in their holes until you die of old age, but it also works great for drilling mounting holes in fenders just above the brake line that goes to the rear wheel.

PLIERS:
Used to round off bolt heads.

HACKSAW:
One of a family of cutting tools built on the Ouija board principle. It transforms human energy into a crooked, unpredictable motion, and the more you attempt to influence it's course, the more dismal your future becomes.

VISE-GRIPS:
Used to round off bolt heads. If nothing else is available, they can also be used to transfer intense welding heat to the palm of your hand.

OXYACETYLENE TORCH:
Used almost entirely for setting various flammable objects in your garage on fire. Also handy for igniting the grease inside a brake drum you're trying to get the bearing race out of.

WHITWORTH SOCKETS:
Once used for working on older British cars and motorcycles, they are now used mainly for impersonating that 9/16 or 1/2 inch socket you've been searching for for the last 15 minutes.

DRILL PRESS:
A tall upright machine useful for suddenly snatching flat metal bar stock out of your hands so that it smacks you in the chest and flings your beer across the room, splattering it against that freshly painted part you were drying.

WIRE WHEEL:
Cleans rust off old bolts and then throws them somewhere under the workbench with the speed of light. Also removes fingerprint whorls and hard-earned guitar calluses in about the time it takes you to say "Ouch...."

HYDRAULIC FLOOR JACK:
Used for lowering a motorcycle to the ground after you have installed your new front disk brake setup, trapping the jack handle firmly under the front fender.

EIGHT-FOOT LONG DOUGLAS FIR 2X4:
Used for levering a motorcycle upward off a hydraulic jack.

TWEEZERS:
A tool for removing wood splinters.

PHONE:
Tool for calling your neighbor to see if he has another hydraulic floor jack.

GASKET SCRAPER:
Theoretically useful as a sandwich tool for spreading mayonnaise; used mainly for getting dog-doo off your boot.

BOLT AND STUD EXTRACTOR:
A tool that snaps off in bolt holes and is ten times harder than any known drill bit.

TIMING LIGHT:
A stroboscopic instrument for illuminating grease buildup.

TWO-TON HYDRAULIC ENGINE HOIST:
A handy tool for testing the tensile strength of ground straps and brake lines you may have forgotten to disconnect.

1/2" x 16"-INCH SCREWDRIVER:
A large motor mount prying tool that inexplicably has an accurately machined screwdriver tip on the end without the handle.

BATTERY ELECTROLYTE TESTER:
A handy tool for transferring sulfuric acid from a car battery to the inside of your toolbox after determining that your battery is dead as a doornail, just as you thought.

AVIATION METAL SNIPS:
See hacksaw.

TROUBLE LIGHT:
The mechanic's own tanning booth. Sometimes called a drop light, it is a good source of vitamin D, "the sunshine vitamin", which is not otherwise found under motorcycles at night. Health benefits aside, its main purpose is to consume 40-watt light bulbs at about the same rate that 105-mm Howitzer shells might be used during, say, the first few hours of the Battles of the Bulge. More often dark than light, it's name is some-what misleading.

PHILLIPS SCREWDRIVER:
Normally used to stab the lids of old-style paper-and-tin oil cans and splash oil on your shirt; can also be used, as name implies, to round off Phillips screw heads.

AIR COMPRESSOR:
A machine that takes energy produced in a coal-burning power plant 200 miles away and transforms it into compressed air that travels by hose to a pneumatic impact wrench that grips rusty bolts last tightened 60 years ago by someone and rounds them off.

PRY BAR:
A tool used to crumple the metal surrounding that clip or bracket you needed to remove in order to replace a 50 cent part.

HOSE CUTTER:
A tool used to cut hoses 1/2 inch too short.

[flb_78]

A jet in the carb is plugged up most likely. Most likely you'll need to disassemble the carb and clean it. You might be able to feed some Seafoam through the carb and loosen it up.

[Commander Cody]

+1

[lonewolf]

Sounds reasonable to me as well. Cleaning the carb is next. The lever you release on the handle to shut it off removes the spark, so if they cable were indeed stretched, it would not even start.

[glbedd53]

It won't help for this time but use Sta-Bil or some other fuel stabilizer, especially during the winter. The ethanol in our gas now is causing havoc with carburetors, especially the ones that gas (and ethanol) sits in for long periods. Most of the manufacturers now are not recommending draining or running the gas out when not in use because of the alcohol. Better to leave the gas in there as long as there is stabilizer in with it.

[Tass]

A jet in the carb is plugged up most likely. Most likely you'll need to disassemble the carb and clean it. You might be able to feed some Seafoam through the carb and loosen it up.

Had same problem with my Honda a couple of years ago....this did the trick.

[powerboatr]

the O ring on the carb tube that lets the air fuel charge enter the cylinder head is what i would check if the carb is clean
pumping the primer is a dead give away its sucking air and leaning out, thus stalling
you can test it by applying grease around the or ring connection on the tube, and start it up, if runs good for say 5 minutes then its the problem.
after about 5 mins the grease will warm up enough to loose its seal.

[rdcrags]

I just last week resolved the same symptoms with my generator. Either choked or not choked, it would run 4 seconds and stop. Here's what I did. After wearing out my arm pulling the rope many times over a 2 day period, I tapped the carburator with a hammer. Then, I discovered that it would run on 3/4 choke position, missing as it ran. But it ran. That gave me a chance to pour some carb cleaner in the gas tank, using the recipe on the can. After 10 minutes, I was able to go to no choke and it continued to run. After another 15 minutes it quit missing. Every 2 days since, I start it and let it run 5 minutes, just to be sure it's fixed. I starts on the first crank every time and runs unchoked after starting it on full choke and immediately stopping the choke.

[jimlongley]

A jet in the carb is plugged up most likely. Most likely you'll need to disassemble the carb and clean it. You might be able to feed some Seafoam through the carb and loosen it up.

What he said.

[G.A. Heath]

My first thought as well is the carb is dirty, however if that is not the case then you may want to check the muffler to see if its plugged up.

[glbedd53]

Yeah, that too. Not an uncommon thing but it's more common on 2 cycles.

[Abraham]

If I won't be using any of my gas running machines for a month or more, I run them til all the gas is used up. This way there's no gas left in the carb to cause fouling next time I fire them up.

This approach has never failed me.