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flipfriddle
Ailing lawn mower

I was wondering if any of you had an idea what might be wrong with my lawn mower. It's 7 years old, some model I bought at Lowe's, with a 3.5hp Briggs&Stratton pull-start motor. Last summer it started having a strange idling problem, where it would start, the revs would rise to normal and then they would drop to a low idle just above stalling, then back up to normal, down again, and so on. Kind of like a throb. I've changed the oil and air filter and spark plug, but that didn't affect anything. Could the carbeurator be fouled, or the fuel filter, or fuel tank be a problem? I'm just wondering if there is any simple fixes to try before I just give it away and buy a new one. Thanks for the help.

A. Spruce
Re: Ailing lawn mower

It's probably a fouled carb or the diaphragm inside it is no longer supple. If you're handy, you can easily get a rebuild kit and go through it yourself, if not, take it to a shop and for around $50 they'll do it for you.

dj1
Re: Ailing lawn mower

You've already invested around $25-$30 in this machine.
It's all a question of "is it worth it?"
A new mower with a 3.5 HP engine is around $120. In the fall, at clearance time, you can buy one for half that.
So it's how badly you need your mower and whether or not you want to continue pouring money into your it.
I would get rid of it and buy a new, more powerful mower. Because when I need the mower, I need it to work, not to be serviced. AND, maintain it properly, so I don't have a breakdown in the wrong time.
Good luck!

Cougars1996
Re: Ailing lawn mower

These less expensive, and even better grades, of push mowers don't last very long these days. The motors can literally wear out after only a couple hundred hours of use (bearings, piston rings, etc.). Add to that the cost of a new blade after a number of years, etc. and the previous post is right.

After 7 years, you've gotten a good run out of it! With that basic kind of mower (3.5 HP), it is probably better to just replace it rather than put more money into it. In the future, with regards to the carb, etc. at the end of each year, let the gasoline run down low. Add STABIL or another preservative to the small amount of gas remaining and run the mower for 10-15 minutes. Drain the rest of the gas and let the mower run out. Then, the old gas is gone, the carb is run empty, and any little gas that is left won't degrade.

You'll have no problems at all for the life of the mower! I did this with a Crapsman (oops Craftsman) I had and it really did last 10 years!

ed21
Re: Ailing lawn mower

It sounds like you have a fuel delivery problem probably caused by crud or gum.
Try running a good strong dose of Sea Foam through a tankfull and see if it helps. I've had good luck clearing up carb problems with it

Re: Ailing lawn mower

Sea Foam? Is that something easy to find at a home center or should I be going to a small engine/lawnmower shop?

ed21
Re: Ailing lawn mower

Auto parts store or marine store. Pep Boys sells it.

canuk
Re: Ailing lawn mower

Sounds to me it's like others mentioned --- fuel delivery or carb issue.
By chance did you drain the fuel from last fall -- or are you using that half tank of old fuel left over from then ?

My mower was purchased in 1990 and still works flawless -- only money on parts was a blade.
In the fall before putting it away for the winter -- the remaining fuel is drained.
Spring --- oil drained -- plug removed to clean and gap -- blade is sharpened ( checked for balance ) -- filter cleaned and re-oiled ---- before putting fresh fuel in and started for the first time.

Sounds like a little maintenance is all it needs but if you follow some of those who advise dumping it and buying a new one --- well -- it's your nickel.
Folks like me don't mind folks like that who throw out perfectly good equipment -- a little maintenance and you have a perfectly good piece of equipment for next to nothing.

A. Spruce
Re: Ailing lawn mower
canuk wrote:

Sounds like a little maintenance is all it needs but if you follow some of those who advise dumping it and buying a new one --- well -- it's your nickel.
Folks like me don't mind folks like that who throw out perfectly good equipment -- a little maintenance and you have a perfectly good piece of equipment for next to nothing.

You and me both. I have a very hard time tossing something that needs $30 worth of TLC for another machine that can easily reach $200 - $300 if not more to replace.

My mower gets an oil change at start of season and the fuel tank topped up. I don't use fuel extenders, I don't drain the tank. It starts on the first or second pull every time! Now, it needs to be said that I don't live in an area prone to freezing, which affects fuel AND the amount of condensation that will occur in the tank over the course of the usable season as well as it's dormant season. That being said, it's actually better to store your equipment with a full tank than an empty tank because of the condensation issue. You can always drain it and replace it if you want, but IME it's not been necessary.

dj1
Re: Ailing lawn mower

Spruce
I fully agree with you that it would be more economical to fix a small engine rather than replace the mower, IF the person who's asking the question knew how to do it AND IF the numbers penciled out.
BUT, if he/she is asking how to do it, he/she probably doesn't know to fix and maintain it.
Now the numbers: a new 3.5 HP mower is $120, not $200-$300.
When Walmart clears them, they go for $50 - $60.
Does it make sense for the average homeowner, who doesn't know how to fix and maintain the mower, or doesn't have the time to do it, to spend $30 on parts, then $50 at the shop, and what if the shop is 20 miles away, then a little fortune on gas - all for a 7 year old mower?
Real DIY's will try to tackle unfamiliar repairs, because that's what they love to do. However, an average homeowner, with only 1 or 2 hours of free time on the weekend to cut the lawn, can't mess with a mower that wouldn't start or cut. Therefore, replacement is cheaper for them. And the same is true to other yard machines. Or cars: would you repair a transmission on an old car knowing that it costs more than the value of the car?

HoustonRemodeler
Re: Ailing lawn mower

I too am in the camp of repairing the old one.

Seems to me a bit more maintenance than had been happening will keep this mower going until the deck rots out. An occasional cleaning along with a jigger or two of SeaFoam (great stuff BTW) in the tank will keep it purring.

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