Lawnmower won't start

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  #1  
Old 08-13-03, 08:18 AM
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Lawnmower won't start

Before I bring my lawnmowe to the local shop, I'm hoping I can get some advice here so that perhaps I can fix it myself.

I have a craftsman LM that just will not start. About a month ago, it was giving me a problem, not on the initial start up, but on subsequent startups, For example, I'd start it up, cut the front lawn, then stop it. When I went to restart it for the back lawn, it would not start. I would have to wait a while then try again for it to kick over. Now, I cannot even get it to start at all. I changed the spark plug and filled up with fresh gas. Still, no luck. Is there a checklist of things I should be looking for in this situation and are they not too complicated? I have tools and am fairly competent and would like to try and fix this myself. I just don't know where to start. Been laid off from work for the past couple of months so any dollars I can save by doing this myself would be fantastic.

Thanks in advance for any help.

Bubba
 
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  #2  
Old 08-13-03, 09:39 AM
Joe_F
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Take out the spark plug---spray Gumout or fuel into the chamber.

If it fires up, runs for a few seconds and dies, you have a fuel problem. Try that first.
 
  #3  
Old 08-13-03, 11:57 AM
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thanks, Joe! I'm going to give the gumout a try. I took a stab at taking the carburetor off (followed some online instructions and referred to the parts list that came with the lawnmower) and upon disassembling everything, all looked clean...no gunk or residue anywhere. Put everything back together but still no luck. So, I'm off to the store to get the gumout and will let you know how things go.

bubba
 
  #4  
Old 08-13-03, 01:25 PM
Joe_F
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If it's a carburetor with a float in it (kinda looks like a brass toilet seat ), typically, the brass screw that holds the bowl gets clogged. The holes are very tiny, use a wire and some Gumout to clear them through.

If this hole gets clogged, the machine won't run
 
  #5  
Old 08-13-03, 03:20 PM
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Hey Joe,

okay, I'm stumped now.

I tried everything I think...

1) Installed new spark plug
2) Sprayed into plug opening with Gumout
3) Disconnected the fuel tank and drained all fuel, replacing with fresh
4) Disconnected Carburetor, cleaned with gumout, cleaned holes in the nut that holds the bottom of the carb (float)
5) Checked the fuel line for any obstructions

I did achieve some success though. After doing all of the above, the engine started, fluttered a bit, then ran smooth. I stopped it, only to try and see if she would restart again. No go! Since stopping, I cannot get her to start. Any other ideas? I'll give it another go tomorrow morning but if it doesnt start, I'll have to bring it to the repair shop...grass is getting too long.

Thanks again for all the help thus far.

bubba

P.S. One other thing I forgot to mention (and this may be important) when I pump the primer button, I'm not sure if it is working. Usually, after three pumps, I can feel the gas in there. This is not happening any more, I don't think. Not sure how to fix this so any ideas are welcomed.
 
  #6  
Old 08-13-03, 03:53 PM
buttlint
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bubbad,

Take the air clearer off, and look into the throat of the carb. Pump the primer as recommended, and see if you can see fuel pouring out of the little tube protruding in the middle of the carb. You should see a pretty decent flow coming up from it.

If you dont, there could be several causes. The float chamber must be sealed for the primer to be effective. First, is the large o-ring (631028) in good shape. (bowl gasket) Check that the carb and the bowl that, that o-ring seals, is clean and free of corrosion. If that o-ring isnt forming a good seal, you cant pressurize the fuel in the bowl, to force it into the throat of the carb.

Second, you can check the condition of the primer bulb. There shouldnt be any cracks or holes. There is no way I can explain this, but sometimes thru age, the bulb just wears out. It looses its elasticiy, and "flattens" out. (like an unstimulated nipple?) It cant push the volume of air necessary to push the fuel up into the throat of the carb.

It's all about getting fuel into the throat of the carb, to get things moving. The engine has to be "warm" before you dont need to prime. That generally means running for 5 or more minutes.

There are other things to check if its not priming, but those are the 2 easiest. When you are looking too see if it is getting a good prime, you should see the fuel rising at least an eight of an inch, above the top of the nozzle.

Hope this helps, but if not, we go from there. 'lint.
 
  #7  
Old 08-13-03, 04:06 PM
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THanks, Lint! Tomorrow is another day and I will try what you suggested first thing. This just may be the problem, as I cannot detect whether or not the priming is working...don't think it is though. Will post back with the results...

bubba
 
  #8  
Old 08-13-03, 05:12 PM
uh2
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I have the exact same thing going on with an MTD lawnmower. I had cleaned the air filter..replaced the spark plug, and it started right up. I thought the problem was solved. Then I went to use it a week ago, same thing again. Before, I could keep it running by continuously priming. Now, priming it doesn't keep it running..it won't even stay started for 2 seconds. I have played around with the spark plug wire, and it started right up...so I was thinking that was the culprit...again, no go.

If you come up with anything, let us know..I'll do the same.

Uh2
 
  #9  
Old 08-13-03, 05:33 PM
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Will do, UH2! I would like nothing better than to see others benefit from my unfortunate situation!
 
  #10  
Old 08-13-03, 11:07 PM
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Hello bubbad!

There are a few basic things to check here that will lead us directly to your problem. If you haven't found the problem yet, by the reccomended advice, we should start from the beginning. Does the spark plug spark when you crank the engine? (check visually). Does the engine run momentarily when you squirt some gas into the plug hole and try to start?

The carburetor on these things is a common problem, and that is why we are all jumping to the conclusion that it is a fuel problem, but we don't know if it is sparking or not. It could be that the kill switch is not entirely disengaging, or other things. What is the model# of your engine?

uh2...your description of your problem is definitely indicative of a carb problem. Remove the small bolt that holds the carb bowl on. On the sides of that bolt are 3 tiny holes. 2 of them oppose each other near the head of the bolt, and one is near the end, in a section of the bolt that is un-threaded. This one is very small and often can't be seen if it is clogged. There is also a small hole down in the center of the bolt. All 4 of these holes need to be completely clear for the engine to run properly. This info is assuming you have a tecumseh engine on the mower.
 
  #11  
Old 08-14-03, 07:48 AM
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Hi Cheese,

how do I check for spark? Also, could it be that the solid state ignition is going/has gone bad? This lawnmower is only three years old (craftsman model # 917.388620) 6.75 HP. I still have to check the issue of the priming...I seem to be missing some hose clamps and wonder if that might be a source of the problem.

Anyway, still taking a crack at this because I feel like I have done so much thus far.

bubba
 
  #12  
Old 08-14-03, 07:50 AM
Joe_F
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If you pull the cord with the plug attached and out of the hole, you should see a spark across the electrode. It should be fat, blue and consistent. If not, ignition problems.

My vote: If you squirted fuel in the chamber and it runs every time you do that, chances are the ignition is OK and it's a carburetor problem. But, as Cheese said, stranger things will happen .

That machine is an AYP (model prefix 917) with a Tecumseh engine more than likely.
 
  #13  
Old 08-14-03, 07:53 AM
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Thanks Joe! If, when I check for spark and do not see any, what does that mean? Is the ignition shot? Is the wire that connects to the spark plug bad? I just put a new spark plug in yesterday so I know it's not the plug. Plus, I got the engine to start yesterday so I'm puzzled. Not giving up though!!

thanks again,

bubba
 
  #14  
Old 08-14-03, 09:02 AM
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Okay, tried the spark plug test and did NOT get a spark. This is with a new spark plug, too. What next?? Am I at the point of needing service from the local shop? If it's a complex fix then I'm just going to bring it in. If not, then I'll give it a crack.

Thanks

Bubba
 
  #15  
Old 08-14-03, 09:50 AM
Joe_F
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You could have a problem where the the coil unit is being grounded out as Cheese stated earlier.

How long will it run if you squirt fuel into the chamber???

Try this:

The next time it wants to start, try to prime it while it's fluttering/stalling. If you can stoke it with the primer, safe bet it's a carburetor/fuel issue.
 
  #16  
Old 08-14-03, 10:19 AM
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Hey Joe,

well, as much as I'd hate to admit it, I gave up. Just dropped off the mower to the local shop. I think I tried everything I could have and even gave it one last go with some fresh fuel in the spark but nothing happened. I'll report back when I find out what the problem is, this way, it might benefit others who are going through the same thing. Many thanks, again, for all your help (and everyone else too).

bubba
 
  #17  
Old 08-14-03, 10:42 AM
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I have a similar problem with my uncle's mower (see the post a few down from yours).

My uncle is adamant that he needs a new mower, which peeves me. It's something dumb, so I've offered to take it from him (he's going to throw it out anyhow) to learn on. I've fixed numerous machines before with simple TLC and basics, this one should be no exception.

I fixed it once before this spring! .
 
  #18  
Old 08-15-03, 12:07 AM
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Oh man, just when we found out what was going wrong, you took it to a shop, lol. Oh well. You have now narrowed the problem down to an ignition problem. My money is on a bad safety bar cable, not releasing the kill switch mechanism enough. It could also be a shorting wire or bad coil (doubtful). Probably would have cost you about $10.00 for the cable, and 10 minutes of time.

Let us know!
 
  #19  
Old 08-15-03, 05:53 AM
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hey cheese,

man, you really know how to make a guy feel good! LOL

well, I'll let you know if your guess is on the money once I hear back from the shop.

bubba
 
  #20  
Old 08-15-03, 04:03 PM
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Lol, sorry. Don't mean to dampen your spirits, I just wish we could have had a tiny bit more time to diagnose your problem. Keep us posted!
 
  #21  
Old 08-15-03, 05:42 PM
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No worries, cheese!

It just got to the point where my frustration got the best of me. While being out of a lawnmower, I had to borrow from others while I tried to fix mine. I'm just uncomfortable asking time and time again, if you know what I mean. ANyhow, I am happy with what I was able to do on my own up til this point. Gave me a boost of confidence to try and tackle things the next time they occur. I'll post back once I get my mower and let you know what the problem was.

Thanks!

bubba
 
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