Ok It started this 2 weeks ago, but its been raining so Im just now getting to mow,

It Starts strong for 2 seconds, then sputters as RPM goes up and down, then runs strong for the last little bit of gas (3-5 seconds) and stalls.

I've:
Replaced the Spark Plug,
Changed the Oil,
Taken off the Air Filter, (cleaned)
Replaced Gas w/ Gas Fresh from the Pump.
Taken off the Gas Tank and emptied/cleaned off,
Sprayed with Carb/Choke Cleaner.

I Also bought some $10 can of Marine Foam i think its called, that didnt help eitehr, Im about to take the gas tank off again and spray cleaner through the entire primer and stuff.

What sort of lawn mower, what engine?

Cheers!

Rick...

Briggs and Stratton engine?
If so it sounds like the pump diaphram between the carb and fuel tank has gone bad.
Make sure both the tank and carb are clean when you replace it.
Costs about 5 bucks and isn't really all that hard a job.
Hope this helps.

WOLF

Exactly.

Cheers!

Rick...

Yup, fuel pump is definitely the prime suspect.

Took the Carb Assembly off the Gas Tank and sprayed it clean,

Will Take Pics and Upload In a Minute.

Craftsman Briggs And Straton 158cc 5.5 Ft Lbs Torque Push Mower, And the Pics will be camera phone pics, as my digital has decided not to work.

Also It Runs Really Rich when it runs, and the Spark Plug gets Gummed up really quick.

So far Lowes, Home Depot and Advanced Auto dont have the Diaphragm, Im out of Time, Im gonna have to it all together and try to finish this lawn before the City people write my parents up again...

I'll prolly wait till next Saturday and hit up some lawnmower shops before I buy it online, IM not sure of the exact part numbers yet either.

Apparently the Spring that controls the choke(?) has been stretched/bent up too.




Pictures of the Diaphragm, Obviously this is bad...

I got fed-up with out petrol lawn mower as it needed to get repaired every two or three times we used it, so it got ditched and I bought an electric one. So far it's paid for itself about four times over.

Isn't this new 'green' gasoline wonderful? It's ruined several small engine carbs for me, too. That ethanol not only reduces the BTUs in the gas, resulting in higher fuel consumption, it also eats rubber gaskets like they were candy. The politics of this makes my blood boil...sorry.

My source for small engine parts is the local NAPA store. If they don't have something in stock (rarely), they can have it the next day almost every time.

Wish it were that easy for my job, damn roofers left a mess of staples and nails around my building when they finished
up on Friday, Now I have 3 flats I need to get fixed before I can mow again. Not fun job my Kubota F3680. Need to change
the oil while await 2 new tires to arrive. 36 horse diesels are easy to take of. Its changing out the tranny fluid that`s
gonna suck when I get to it. almost 5 gallons worth.

All 3 tires on this side are flat, going to have get out magnet and go over everything out there.

Someone actually mentioned that..

he found somewhere that used old octane fuel or something like that for his lawn mower.

this mower is less than 2 years old.

Sounds like 2 of my mowers. Got the carb rebuilt on the riding mower, the float was sticking, even though the tank was empty the last bit of remaining gas has turned to varnish. The guy told me for the self-propelled to just order a new carb. Said the carbs on the small engines don't take to rebuilding well, easier to replace it and not that expensive.
The riding mower that he rebuilt the carb on runs like a dream now.

tehe gasket/dia is only like 5 bucks..

I managed to do my lawn by messing with the gasket during re-assembly. its only a temp fix though.

You can usually find the model number for the engine on the cranktop housing of the motor or check online at the Sears Parts website for the exact location.
If the choke spring is bent you definately need to replace it and as vocatex said, try the NAPA parts place.
They are an official Briggs and Stratton parts supplier in most locations.
You might also want to check around and see if any of the local gas stations offer fuel without ethanol, it'll save you a world of trouble with most small engines.
I see the tank decal states the mower will run on it but I'd take that with a grain of salt since while the ethanol may not attack the material the carb is made from it'll most definately attake the gaskets and the diaphram material.
Goodluck, small egines can be a pain in the ass to work on sometimes.

if that mower is stored outside, and got rained on the ethanol in the gas probably absorbed some water. they will sputter and misfire until it is all run out. the simple fix is usually to loosen the nut on the bottom of the carb bowl and remove the bowl, letting some new gas flow through, once the float drops. those gaskets often look bad when removed, but will continue to work unless disturbed.

JimK, have you tried "slime" in those tires? I use it because of all the thorns I mow over, it works well on nails and staples.

Yep, slime works really well. I run it in my Ranger tires. One thing about Slime, though, is you have a fairly good leak it sealed and you park with the hole where the Slime will run off the hole, it will go flat overnight. A plugging kit is cheap and easy to use on tires like these.