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Lawn Mower not running right

KeithP

Diamond Member
Jun 15, 2000
5,473
99
91
I have a OLD Craftsman lawn mower. Last season I replaced the carburetor and everything seemed to be okay until recently. Now the engine is down on power.

I am not familiar with Briggs and Stratton engines or how they are designed to work. That being said, I found that adjusting a spring (see pic) on the carb got it back running okay. It held the throttle/butterfly valve (white piece in picture) open more which restored power. My question is does this pose any issues? My concern would be that I could possibly set the engine so it runs at a higher RPM than it was designed for an extended period of time.

Any thoughts? Thanks.

IMG_20190126_151351 small.jpg


-KeithP
 

C1

Platinum Member
Feb 21, 2008
2,233
52
91
You may be attempting to compensate for a disfunctional governor. Make sure that the governor system and linkage are clear of dirt/debris and move freely.

The lawn mower engine should be able to function okay across a wide range of RPM. The speed setting also can be somewhat a function of the condition of the lawn that is being cut. Low grass on a flat lawn wont require as much power, but Ive had cases in which Ive had to pretty much do what you've done. Mainly, increase the mower's RPM setting by putting more tension on the throttle governor spring to cut a lawn consisting of tall wet grass.
 

Greenman

Lifer
Oct 15, 1999
14,358
1,128
126
I wired mine open, it was like having a turbo mower, thing would chew through tree stumps. My hunch is the only real concern is the blade or drive shaft breaking. A lot more stress on those components at higher rpm. I guess throwing a rod in the mower is possible as well.
 

pcgeek11

Lifer
Jun 12, 2005
15,510
1,134
126
You should be fine. It was in days long gone the lawnmower had a throttle cable that operated the carb manually. In those days everybody ran wide open throttle when cutting the grass. Maintain the oil and keep on cutting. I to manually adjusted the governor for a more meaningful cut.
 

KeithP

Diamond Member
Jun 15, 2000
5,473
99
91
FWIW, I popped the top cover off along with the piece that holds the pull cord. Gave everything a good cleaning (it was really caked in a few spots). Also put in a new spark plug. I don't know the maintenance history of the mower, it was my Dad's and I got it after he passed away in 2017. It seems to be running fine now.

-KeithP
 

TXHokie

Platinum Member
Nov 16, 1999
2,416
81
91
If you're not already, use non-ethanol gas only (find nearest place here - https://www.pure-gas.org/). The regular ethanol mix gas used for autos these days will gum up those small engines over time.
 

WilliamM2

Golden Member
Jun 14, 2012
1,664
65
91
If you're not already, use non-ethanol gas only (find nearest place here - https://www.pure-gas.org/). The regular ethanol mix gas used for autos these days will gum up those small engines over time.
It may eventually eat the hoses and other rubber parts in the carb, especially if it sits a lot. It will not "gum up the engine". It won't hurt the engine at all. I've got a 12 year mower that has had no issues with ethanol gas. I do have a leaf blower that the ethanol ate all the hoses after 11 years. Cost $18 for a new carb and all the hoses to fix it. Glad I didn't pay an extra $2 a gallon for ethanol free gas all these years to prevent that huge repair.
 
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KeithP

Diamond Member
Jun 15, 2000
5,473
99
91
FWIW, I popped the top cover off along with the piece that holds the pull cord. Gave everything a good cleaning (it was really caked in a few spots). Also put in a new spark plug. I don't know the maintenance history of the mower, it was my Dad's and I got it after he passed away in 2017. It seems to be running fine now.

-KeithP
Well, it is no longer running fine. I went to mow the lawn the other day and when I tried to start it, I discovered the engine had seized up. It is not an oil issue. I had changed the oil for this season and always check the level before each use.

In any event, given its age, I told myself after working on it last time that if anything, no matter how small, goes south on it again I wasn't going to deal with it…just replace it.

I end up getting a manual push mower (this one). It has some pros and cons but works reasonably well.

-KeithP
 

KeithP

Diamond Member
Jun 15, 2000
5,473
99
91
You must have a small yard to cut grass with that torture device. I haven't seen one of those in use in decades.
Torture device? LOL. Not even close. It is lighter and less work to push it around my lawn than the gas mower was. Maybe a self propelled gas mower would be easier but that wasn’t what I had.

I suppose if someone had some physical problems where any amount of exercise would be a problem, a self propelled mower would be better. Of course, if that was the case, they should probably hire someone to mow their yard.

Sharpening kits are available, so keeping it sharp and properly adjusted won’t be much of an issue.

- KeithP
 

pcgeek11

Lifer
Jun 12, 2005
15,510
1,134
126
Torture device? LOL. Not even close. It is lighter and less work to push it around my lawn than the gas mower was. Maybe a self propelled gas mower would be easier but that wasn’t what I had.

I suppose if someone had some physical problems where any amount of exercise would be a problem, a self propelled mower would be better. Of course, if that was the case, they should probably hire someone to mow their yard.

Sharpening kits are available, so keeping it sharp and properly adjusted won’t be much of an issue.

- KeithP

I wish you well.
 

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