B&S lawnmower won't start now

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  #1  
Old 06-20-08, 09:28 AM
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Question B&S lawnmower won't start now

Hey folks,

Prob with my lawnmower. Used to run well -- until 2 weeks ago. Then engine strength not at full power. A small amount of idling from it. I therefore changed the air filter and oil 2 weeks ago. Today, lawnmower engine stopped. Won't start up after pulling cord. I checked the spark plug. Very black. Cleaned it. Still wouldn't start. Spark plug muffler charcoalish colour inside. One of those without external screws, so can't open it up.

http://i266.photobucket.com/albums/i.../BSmuffler.jpg

So, my questions are:

1) Should I first change the spark plug before doing anything else?

2) Is my muffler the type that can be spray cleaned with carburetor cleaner, or is that only with the type where you can open it up fully?

3) How would you suggest I remove the black stuff from the muffler? (I've tapped it, to shake out any black powdery stuff, but there was none.) Or do I just have to buy a new one?

4) Is cleaning out the carburetor the last DIY course of action?

Please help us out...cheers in advance with yer advice...

RS
 
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  #2  
Old 06-20-08, 10:36 AM
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To follow up, here is what my muffler kind of looks like. Carbon build-up inside. But no rust on mine like the one pictured. No screws to take it apart, to thoroughly wash it out inside. Only two bolt holes, for attachment to mower's side. So would you suggest a wire-brush clean through those holes, or soaking in some type of chemical? Please help us out on this matter, and the other ones asked, asap! PS. Is cleaning out the carbon build-up from the muffler essential maintenance, i.e. vital? Or does muffler cleaning not make much of a difference. Would appreciate your advice on all/any of these matters.

Cheers in advance,
RS

http://i266.photobucket.com/albums/i...ledmuffler.jpg
 

Last edited by Rollingstone06; 06-20-08 at 10:43 AM. Reason: Grammar and text edit
  #3  
Old 06-20-08, 11:01 AM
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The muffler is almost never an issue, I would put everything back in place, then remove the air filter, then give a quick
squirt of carb cleaner in the the carb throat, and try to start.

If it starts, and runs for a second or two, then you have a
fuel problem. If not, then it is either ignition or compression related.
But first find the engine's model numbers so we know which engine you have.

Fish
 
  #4  
Old 06-20-08, 11:16 AM
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Cheers for the reply. It's a Stiga 40 Collector with B&S classic engine. 2003 model. Bought it new only 3 years ago. About what you said about carb cleaner, should I just replace the spark plug first, and then if that works, no need for me to buy carb cleaner for the carb throat?

Cheers in advance...
RS

Originally Posted by Fisher40037 View Post
The muffler is almost never an issue, I would put everything back in place, then remove the air filter, then give a quick
squirt of carb cleaner in the the carb throat, and try to start.

If it starts, and runs for a second or two, then you have a
fuel problem. If not, then it is either ignition or compression related.
But first find the engine's model numbers so we know which engine you have.

Fish
 

Last edited by Rollingstone06; 06-20-08 at 11:31 AM. Reason: Text edit...oops
  #5  
Old 06-20-08, 01:05 PM
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Please post the engine Model, Type and Code usually found stamped in the engine shroud just above the sparkplug. In your post you stated it was a B&S Classic which to me would indicate the carb is setting on top of the fuel tank. With that said;
You need to install a new diaphram kit, it is Briggs part # 795083 or old # 495770 also Lowe's has a kit #5083 which has the same parts.

Here we go;
Remove air cleaner, there are 2 bolts that hold things together, one on the front of the tank 3/8" and one into the block 1/2", remove these bolts, now "slowly" slide the carb/tank off the intake tube and breather tube, now tilt the tank in to release the throttle linkage and waalaa the carb/tank is removed. Remove the 5 screws from the carb/tank remove carb(don't loose the spring) now spray all holes, cracks and crevases in both the carb and tank surface with brake parts cleaner, remove the main screen(looks like a thimble) with a small screwdriver pry out the main jet(carefully) and clean it, reinstall the jet, it can be difficult some times to get it to snap back in place(I use the rounded end of a screwdriver handle). Remove and clean the fuel pickup stem. Clean any junk/rust from the tank. Install the diaphram on the tank then the gasket(no goo or sealer) now carefully replace the carb(the spring will try to misalign the diaphram), tighten all screws a little at a time so as not to crimp the diaphram until they are all tight. Install the carb/tank in reverse order and you are done. If I missed something one of the real mechanics will correct me. Have a good one. Geo
 
  #6  
Old 08-29-08, 05:41 PM
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Question Model 10D902; Type 0153B1; Code 03100651

Folks, after a long break from here dealing with other DIY projects, and after returning from a summer vacation, I'm now returning to this matter. Many thanks, albeit belatedly (my apologies), disher & geogrubb, for your answers. Very much appreciated. I just checked out the engine number, etc. (Above numbered.) I followed your advice, geogrubb, a few days ago, and replaced the carb diaphragm and gasket. When I was reinstalling everything back into place, I realised that I'd misplaced the carb's spring somewhere in my yard . I then got what I thought was a good enough replacement-type spring from the local spare parts' store. It's a few centimetres long.

After I installed it, and pulled the flywheel rope (and after spraying all the carb's parts with carb cleaner prior to that), the engine started up on the second pull after priming, however it seemed that the engine was only running at half speed. Also, during long grass segments, even with the cutting-height adjusted, it stopped soon after tackling those parts. Seemed to be labouring. (The white lever was positioned away from the steel wheel at that stage.)

I then moved the white lever towards the flywheel, and started the engine up, and it raced like hell . Sounded like a motorbike without a muffler. Bloody noisy. Again, when I moved the lever away from the flywheel, it ran poorly, and sounded like the engine was about to stop.

So my questions now are as follows:

1) Which position should that white lever be in? (Close to flywheel, or away from it?)

2) Is carb spring's length important, and could that be why the engine was running weak? (i.e. precise original length spring is essential for fuel pump function?)


Help us out here, if you can folks. Really wanna get that long tall grass cut out in the lawn. It's now been growing for 7 weeks! Let me know how to proceed.

Cheers in advance, and Photobucket pics as below, to show the alternative positions I used with that white lever.

RS ;-)

http://i266.photobucket.com/albums/i...8/SV300263.jpg

http://i266.photobucket.com/albums/i...8/SV300264.jpg
 
  #7  
Old 08-29-08, 06:52 PM
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Not to sound rude, however, you can't just go get a spring, attach it and say the engine doesn't run right, it has to be the right spring for the right engine, for your model engine there are 5 different springs depending on the type code, now go get the proper spring for your engine. Governor spring B&S Part# 690254 and if necessary the idle spring B&S Part#691859 after installation then post as to how the mower is running and we can go from there. Oh, Have a good one. Geo
 
  #8  
Old 09-23-08, 09:18 AM
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Ok, to update the situation -- replaced with the correct spring. Still didn't run smoothly. Have now bought new carb. That should do it.

Last question -- would you recommend WD40, acetone, or ethanol, to remove the old petrol (sticky residue) which is in the petrol (gas) tank? -- I really wanna get the whole thing clean before I install the new carb, etc.. Also, because that's a really tight area, what tool would you recommend to get it there, to scrub it clean? (A tooth-brush just doesn't have the flexibility.)
Please let us know soon!!!!

Cheers,
RS Beer 4U2
 
  #9  
Old 09-23-08, 04:03 PM
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I would used a spray type carburetor cleaner, should dissolve the varnish pretty well. I am guessing that you are not in the United States, so I am not sure what may be available to you. I can tell you WD40 won't do the job.
 
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