Push mower peters out, then stops cranking

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  #1  
Old 04-09-20, 04:59 PM
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Push mower peters out, then stops cranking

My push mower has a Briggs & Stratton 625ex (093J02-0006-F1) engine which I can pretty much reliably pull-start every day, but then the motor just peters out. Last week, it would go just long enough for me to think it is working (maybe 5 minutes), now it dies in less than a minute and both last week and this, I can restart it once or twice for a couple of seconds, then it will not start at all. This leads me to believe the issue is from the fuel, but I don't really know.

Last May, I replaced the spark plug,
carburetor and air filter. The lawn mower then worked until maybe February, when backfired once and has not worked right, since.

First thing I did was replace the air filter, then I drained the fuel tank by taking loose the fuel line and draining through it, so the line is clear and seems to work fine. I replaced the gas with new, freshly-bought gas. I've poked and prodded at the carb and have made sure the spring on it and the choke spring are working. I've now replaced the spark plug again just for fun.

Another suggestion I've seen is to replace the fuel cap, but none of my local stores stock the one for my mower and before I order one, I wish there was some kind of way to test to see if that's it.

Any ideas or suggestions would be appreciated. My yard looks like crap and now neighbors have started offering to loan me their mowers because it has gotten so bad.

Thanks
 
  #2  
Old 04-09-20, 05:15 PM
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The test for the fuel cap is to run the mower w/o it and see if it suffers from the same symptoms. The thought being the vent has failed and you are pulling a vacuum, thus starving the engine of fuel.
 
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Old 04-09-20, 08:52 PM
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Thinking that may be it, I've tried starting it without a cap or rag stuck in it (with not a lot of fuel) and it does the same. It just knocks off, as if the cap was still there.

Thanks
 
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Old 04-10-20, 05:46 AM
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Gas caps are often the cause of mower stalling but the backfiring is an indication of a different issue. The backfire could be caused by the carb.being set too lean so perhaps you can adjust it.

BTW, what caused the carb. replacement in last year?
 
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  #5  
Old 04-10-20, 08:10 AM
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I'm guessing your coil is bad. Get tools and gloves at hand to remove the spark plug. Run the engine until the engine dies. Then quickly remove the spark plug (wear gloves because it will be hot). Quickly put the wire back on the spark plug and hold the plug so the threads are touching bare metal of the engine. Pull the starter cord and see if you get spark. If you don't have spark then the coil might be bad.
 
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Old 04-10-20, 11:21 PM
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Take the bowl off the carburetor and visually verify a steady strong stream of gas flowing through the inlet needle. Not just a trickle but a flow. Sounds like your fuel flow is not enough to keep up with engine demand.
 
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Old 08-18-20, 06:40 PM
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Update!

I'm resurrecting my old post because the lawn mower still isn't working.

After a while, the motor stopped starting altogether.

Since I last posted, I've replaced the gas cap.

I checked the coil with a multimeter. It was bad, so I replaced it.

It will now briefly start on starting fluid, which it would not do before I replaced the coil, but it shuts out once the starting fluid is burnt.

I now have the carb off and removed the bowl. There was some gas in it, but I don't believe it was full. It certainly wasn't when I removed it, but I don't know whether some spilled out as I was taking out the screws.

I've tried blowing through the gas inlet, but my air isn't going anywhere and when I stick some string trimmer line in, it does not go very deep. I'm pretty sure I threw away the old carburetor, so I don't believe I have parts, but I will take another look around to make sure.

If anyone has any suggestions or would like to give me some direction, I'd appreciate it. I have already put a lot of effort into this mower and I don't really want to give up and take it to a shop.

Below is a pic of the underside of the carb (from within the bowl looking up).

Thanks


 
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Old 08-18-20, 07:07 PM
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Turn the part in the picture down and blow in the fuel inlet. If you can't get air through it the float valve is either stuck or plugged.

Don't be sticking stuff down the inlet tube. You might damage something.
 
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Last edited by marbobj; 08-18-20 at 08:08 PM.
  #9  
Old 08-18-20, 07:10 PM
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Craftsman Carburetor

Remember that "taking it to a shop" is not giving up. It is just using another option to help you achieve your goal. I have gotten a lot of help from people and moderators on the forums here and elsewhere, but once in awhile they get stumped, especially when they can't see, or hear the offending issue. I built a small engine repair business out of machines that people could have "taken to the shop" but just put it out for the trash lol.
 
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Old 08-18-20, 07:27 PM
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marbobj I tried blowing into the inlet -- out the right side of the photo -- it is definitely blocked

It looks like the white horseshoe-shaped thing is the float valve and that it may come off if I slide out the pin (also on the right side of the photo), but though the pin would slide, I thought I'd ask here before taking it apart. The horseshoe-shaped bit moves like a float valve should, though it doesn't move very much, but no mater how it is positioned, I can't blow air through the inlet.

BTW: Though I replaced the carb last June, I bought a cheap knock-off from the big online store..

Thanks
 
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Old 08-18-20, 07:35 PM
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WML13 I appreciate the sentiment, but I'm a DIY guy. If there was a shadetree small engine shop around, I might consider throwing up my hands, but most of the places around here advertise that they do not work on push mowers or will only do maintenance on them, not repairs. The couple of places the review sites and Nextdoor say will work on push mowers have a reputation of taking six weeks and charging $150 just to replace "bad" gas.

And again, I try to be a DIY guy. I don't even take my Prius to the shop.
 
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Old 08-18-20, 08:06 PM
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With the float (white horse shoe shaped thing) hanging down, you should be able to blow through the inlet. That's the path gas takes to get into the float bowl to run the engine.
 
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Old 08-18-20, 09:43 PM
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I could not blow through the inlet with the float valve hanging down, so I removed the pin that was acting as its hinge and the only thing I saw holding it on.

I then tried blowing again to no avail, but could see what looks likes a stopper that I theorized ws pushed by the float to stop the flow. It was definitely stuck, so I tried a little vinegar on a Q-Tip before just pulling it out.

I can now blow through the inlet and there's some goo on the frame of the stopper that I believe made it stuck -- possibly from using gas with ethanol. Though again, it was a cheap, knock-off carburetor which is no longer being sold

I have the pin-like stopper soaking in vinegar while I post this reply. My plan is to clean it and the hole it uses, then try putting the thing back together. If it works, I'll post another pic.

Thanks
 
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Old 08-18-20, 10:27 PM
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Promised Pics

I'm not going to put the mower back together until in the morning, but now that I have the carb back together, I am pretty confident it will work. The float now hangs down much further than it did before and when it is hanging down, I can easily blow through the inlet. Everything seems clear.

For anyone interested with a similar carburetor, the pic above was the all together underside with the bowl removed,

The pin or bolt-like stopper is circled in red on the following pic. It is under the (removed) horseshoe float



To put it back together and to keep in mind when taking it off, the head of mine slid into a track on the float which was easier to put together before putting the float back in place.



Hope this helps someone. Thanks everyone for all of the help.
 
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Old 08-19-20, 10:18 AM
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Tryagain, I ran into a carb similar to yours that not only had a steel pin that acted to stop the fuel flow, but a composite material washer that acted as a valve seat for the needle on the tip of the pin. It had swollen up (probably from ethanol) to the point where I could not set the float to the proper height to allow enough fuel into the bowl. You sound like you are past that now, and I get it about the 100 bucks to drop off a mower and the 6 week wait. If you make friends at a few of those places though, sometimes they don't mind sharing some captive information that they may have gotten from a Manufacturers service bulletin that you would have never seen. I put a new cylinder head on a car that was long out of warranty that the manufacturer would have paid for had I brought it in to the dealer where I bought it. Just saying, keep your options open.
 
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Old 08-21-20, 03:42 PM
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Addendum: Hopefully, final update.

The float valve was definitely stuck which wouldn't let me blow air into the carburetor, so I see no way gas could get into the bowl and what I did above solved that problem, but when it was put back together, the lawn mower went back to petering-out after only starting on carb cleaner.

This prompted me to search again on this forum which somehow led me down a YouTube rabbit hole, where I found a video called "Easiest Way to Clean a Plastic Briggs Carburetor" from "Steve's Small Engine Saloon". For the first time since maybe January, not only could I get my push mower to start, but it ran until the afternoon storms rolled-in.

I didn't do his thing with the drill bit, but straight-up cleaning did the trick.

Next in small engines... fix the broken Honda my wife brought home trying to help.

Thanks everyone!
 
 

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