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ctggzg
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join:2005-02-11
USA
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1 edit

Lawn mower won't stay running

We have a two-year-old Yard Machines / Briggs & Stratton walk-behind mower that hasn't really been maintained in those two years. It was running fine until a few days ago. The engine still starts consistently but now dies after a couple of seconds. Today I replaced a blackened spark plug and dirty air filter, but it didn't help. The oil looks fine. What else could be the problem?



shdesigns
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Stone Mountain, GA

Re: Lawn mower won't start

Most likely a gummed up carb. Second cause would be bad coil.



SparkChaser
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Downingtown, PA
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reply to ctggzg

Re: Lawn mower won't stay running

Have a year old JD walk behind and it had similar problems. It was dirt in the carb.

OT - but the JD walk behind we had for 15 yrs was 100X better than the new one. I noticed the local JD store selling Hondas



dcurrey
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reply to shdesigns

Re: Lawn mower won't start

Had same problem with Lawnboy. Since I don't know squat about small motors had it professional cleaned. Same problem about year later. About month into season. Think it turned out to be cased by bad gas. No I don't keep gas around year long.

Second time around added fresh fuel with fuel stabilizer added. When I little heavy on the stabilizer. (It was this is going to work or I am getting new one anyway.) Keep starting in and pressing the primer bulb just before it would die. It starting running longer and longer. After about 15 to 30 minutes of this it stayed running.

Been over 1.5 years now and no further problems. I keep fuel stabilizer in all my gas for my mowers now.

Don't buy gas from that station anymore.



Pacrat
Old and Cranky
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Cortland, OH
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reply to ctggzg

Re: Lawn mower won't stay running

I suspect it's debris in the fuel line/carb. It's amazing how easily leaf/grass debris can enter the fuel system. Some years ago, I had a Cub Cadet tractor that suddenly started to cough and wheeze, then quit out of the clear blue sky. No problem at all in getting it started, but after a few seconds or a minute it would sputter to a complete "cardiac arrest". Baffled the hell out of me. I cleaned the fuel filter, blew out the fuel line, cleaned the carb, used fresh gasoline... nuthin' worked. The gas tank on my Cub was sort of a translucent white and just on a hunch, I put a bright light under it while looking into the fill hole. Damned if there wasn't a dark shadow where there shouldn't be. After using a siphon pump to remove the gas (most of it anyway) I could actually see part of a maple leaf on the bottom of the tank. The outlet was also on the bottom of the tank and what would happen was the leaf would float/drift around until it got close enough to be pulled over the outlet hole... completely cutting of the flow of fuel. With the engine off, the vacuum would release, and the leaf would just "float" away, allowing the flow of gasoline once more. To verify my apparent diagnosis, I started the tractor, and peered into the gas tank. What I saw was the leaf bit slowly work its way over the outlet hole and the tractor would sputter to a stop. I drained/removed the remaining gasoline and fashioned a "sticky stick" and managed to pull the leaf shard out of the tank. Upon the removal of the foreign material, that Cub purred like a kitten! Now, I'm almost anal about making sure the area around the filler cap is completely clear of any dust or debris before I take the cap off to fuel the Cub. I suspect you have a variation of the same problem.
--
Keep your eye on the ball, your shoulder to the wheel, your nose to the grindstone, and your ear to the ground. Now, try to work in that position!!!



alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1
reply to shdesigns

Re: Lawn mower won't start

I second shdesigns' gummed up carb assumption.

I don't know if you had a long gap between the last time it ran successfully and now. It's possible the carb got gummed up from old fuel while sitting in storage.

My B&S mower was barely a year old, but one single winter in storage without draining the fuel and it wanted to die in the spring. My hedge trimmer was worse off, it would stall seconds after I turned off the choke.

Here was my solution (And do an oil change while at it):

1 - Drain all the old fuel from the tank and fuel line (If you can't/don't know for the fuel line, just keep pulling the string until the engine won't even react).

2 - Find the carburator (Usually it's behind the air intake/filter, so remove that).

3 - Spray carb cleaner (I used aerosol seafoam) into it, make sure the butterfly valve is opened up (Hold the handle down as if the engine was running).

4 - Pretend to start it (Pull once or twice). It might even start for a few seconds. Don't worry about the smoke

5 - Spray more carb cleaner

6 - Let it sit for a while

7 - Now put just a bit of fresh gasoline in the tank and start it without the filter box in the way.

8 - Let it run and a couple of times a minute spray more carb cleaner while it's running.

You should be good to go. If not, you need to dismantle the carb and clean it up.

From now on, never fill up the gas tank.
Always put the minimum quantity you think you'll need to get the job done for that one day. You never know if you'll have a drought and that the grass won't need to be cut for a month or two.

Long gone are the days that you just filled up the gas tank every time and never worried about the age of the fuel



natedj
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Columbia, SC
reply to ctggzg

Re: Lawn mower won't stay running

n/m


ctggzg
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USA
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reply to alkizmo

Re: Lawn mower won't start

said by alkizmo:

I don't know if you had a long gap between the last time it ran successfully and now. It's possible the carb got gummed up from old fuel while sitting in storage.

It had only been a week. I have to mow frequently here in South Florida where it's hot and wet all year.

So it's almost unanimous then. I'll get some carb cleaner and a YouTube crash course on how to use it. If that doesn't work then I'll just have it professionally serviced. There are some black specks at the bottom of the gas tank and it's overdue for oil and blade maintenance anyway.

Thanks.

8744675

join:2000-10-10
Decatur, GA
reply to ctggzg

Re: Lawn mower won't stay running

Probably a gummed up carb or the float is stuck up. My old mower used to do it all the time. Enough gas seeps in to fill the carb bowl, and when you start it the gas in the bowl burns up and it dies because the float is stuck or gas can't flow through the gummed up holes fast enough to keep it running.

Sometimes tilting the mower back and forth on the front wheels and back wheels, and letting it drop several times to give it a jolt will release the float or unclog it enough to mow the lawn.



Jimdaboe

join:2001-01-16
Corpus Christi, TX
reply to ctggzg

It's a plugged jet hole in the carb bowl bolt. Unscrew the brass bolt at bottom of the aluminium carb bowl. Clean out the holes in the bolt (one passage down the middle and either 2 or 3 side holes). You can use a small wire or paper clip. clean out the bowl and reinstall. Done!


ctggzg
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USA
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reply to 8744675

said by 8744675:

Sometimes tilting the mower back and forth on the front wheels and back wheels, and letting it drop several times to give it a jolt will release the float or unclog it enough to mow the lawn.

Sounds like our previous mower that had similar problems before we replaced it. At one point the engine would die if it was tilted just slightly forward when going down an incline. When it sputtered I tilted it on its back wheels and the engine recovered.

Is the carburetor the small part with the air filter on top and the primer button on the front?


shdesigns
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Stone Mountain, GA

Yes, the carb will be behind the air filter and have the primer bulb on it.


ctggzg
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USA
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reply to ctggzg

Arrrrrrgggggghhhh. It took me more than an hour to get the gas tank and what I THOUGHT was the carburetor off. They didn't make stuff easy to get to.

After all the trouble taking things apart, I couldn't find the parts referred to in YouTube how-to videos. There's nothing resembling the bowl or main jet. And everything that I COULD find and reach looked spotless, so I didn't even bother with the carb cleaner. I at least drained the tank and put in fresh gas while I had it off. I put everything back together, and not surprisingly, it wasn't any better than before.

After some more research, I think I have one of these:

»www.youtube.com/watch?v=Gg4OWXW520k


... where the carburetor is built into the tank. I guess I'll take it all apart again tomorrow and follow this guy's instructions.


mix

join:2002-03-19
Utica, MI

Gee I wonder what carb cleaner does to rubber and plastic parts...



alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1
reply to ctggzg

said by ctggzg:

where the carburetor is built into the tank. I guess I'll take it all apart again tomorrow and follow this guy's instructions.

That's intense.

Before I'd go to that extent, I'd drain all the fuel, make sure there is no more fuel ANYWHERE.

Then I'd pour in ONLY seafoam in the tank (Maybe a quarter of a can of seamfoam) and force the engine to go through it. This will force the seafoam into the carburator and clean it up (Just like spraying carb cleaner into the carb).


sempergoofy
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join:2001-07-06
Smyrna, GA
Reviews:
·AT&T Southeast
reply to ctggzg

I had a similar thread to this one back in 2009. You might find some good pointers in it.

»Push mower engine trouble

Epilog on that story is that in the next season after that one, it went bananas while I was using it one day. Never started again. Took it to the dump and bought a replacement self propelled push mower that I like better.
--
nohup rm -fr /&


ctggzg
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join:2005-02-11
USA
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reply to ctggzg

Still no luck. I sprayed carb cleaner everywhere and immediately flushed the plastic parts with water. After reattaching the tank (which was significantly easier than the first time, thanks in part to a socket set), it still won't run.

A couple of people mentioned Sea Foam. I've actually been adding a little of that to the gas every since I bought the mower.



alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1

said by ctggzg:

A couple of people mentioned Sea Foam. I've actually been adding a little of that to the gas every since I bought the mower.

As I mentionned before, try to run PURE seafoam through the engine, even if it won't keep running, force it. It will make a ton of smoke! but it will clean whatever is along the way.

I'd try to pass 1-2 ounces of pure seafoam.


mityfowl
Premium
join:2000-11-06
Dallas, TX
reply to ctggzg

I think that you need to replace that little carburetor diaphragm.



mityfowl
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join:2000-11-06
Dallas, TX
reply to ctggzg

Briggs and Stanton is just a name now.

I'll show you my 30 year old B & S.

1 new diaphragm.



Pacrat
Old and Cranky
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join:2001-03-10
Cortland, OH
kudos:2

You do mean Briggs & Stratton, don't you?



mityfowl
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join:2000-11-06
Dallas, TX

Yes I do.

Sent from an iPhone



mix

join:2002-03-19
Utica, MI
reply to ctggzg

Looks like you have a stange carb., but just so we are 100% clear here, this lawn mower has nothing that is adjustable it terms of the carburetor or throttle controls? The carburetor has no pilot screw, no throttle stop screw for idling, or a choke arm connected by cable to a throttle lever? There is no inline fuel strainer somewhere between the fuel tank and carb.? It's all non-adjustable?

Does your lawn mower come with a make an model number? You might get some better responses...


ctggzg
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join:2005-02-11
USA
kudos:2
reply to ctggzg

Right, nothing to adjust. It's model 10T502-0457-B1.

»i.ebayimg.com/t/B-S-Tank-carbure···0_35.JPG


ctggzg
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USA
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reply to alkizmo

said by alkizmo:

As I mentionned before, try to run PURE seafoam through the engine, even if it won't keep running, force it. It will make a ton of smoke! but it will clean whatever is along the way.

I'd be more inclined to try this if I hadn't been using Sea Foam all along. I'm obviously not an expert on combustion engines, but after the constant Sea Foam additive and then the concentrated shower of carb cleaner, it seems unlikely to me that carburetor gunk is still a possible cause. Are you sure that burning pure Sea Foam isn't bad for the engine?


shdesigns
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Stone Mountain, GA
reply to ctggzg

Might be worth ordering a new diaphragm and gasket. According to the manual part # 795083. Checked ebay and they are available for about $3.

There are also ones with the strainer and spring for about the same price.

Expand your moderator at work

ctggzg
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join:2005-02-11
USA
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1 edit
reply to shdesigns

Re: Lawn mower won't stay running

said by shdesigns:

Might be worth ordering a new diaphragm and gasket.

Done, no change, and another $4 down. I thought about replacing the tank and carb, but that would cost me at least $70 when the whole mower was only $150.

There's also a new symptom the last few times I tried to start it. Now the mower usually starts on the second pull when it used to start on the first ("start" meaning "run for three seconds and die"). Is that a clue?


shdesigns
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Stone Mountain, GA

Sounds like the jet is plugged or the pump is still not working.

Is this a "quantum" engine? I may have a tank, carb and filter that will fit.


iknow
Premium
join:2012-03-25
reply to ctggzg

sometimes diassembling the carb, removing all plastic and rubber, and boiling the carb in water for say, half an hour will loosen junk up, then carb cleaner and an air spray will remove it.