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Craftsman LT2000 247.28902 with Briggs and Stratton 31P677-1373-B2 (19.5 hp)

A week ago I was mowing (3rd time this year) and all of a sudden the mower started running really rough, to the point where it finally shut off. I didn't hit anything, just normal mowing. The mower wouldn't start after that. The engine would spin, but never "catch" and start. I had just put some gas in, however it is possible the gas was old (sitting for a couple months with no stabilizer). I usually churn through my gas quick here in CT between the mower and snowblower but we had an uncharacteristically warm winter.

I did some routine maintenance first (fresh gas with sta-bil, new spark plug, new fuel filter), no difference. I then had a coworker who is a former mechanic clean the carburetor. When I put it back on the mower started but ran VERY rough and rich. Very hard idle and blowing black smoke. Shut it off. Adjusted the idle mixture screw and tried to start again and it wouldn't start. Pulled the spark plug and it was pretty black (no surprise), cleaned it off and tried again, still nothing.

Just looking for ideas at this point. Thanks for any help.

Here is a video link to what I'm experiencing now:

https://youtu.be/GdFAGJCSC2A

:welcome:

The video is a classic no compression release situation.

It can also be a partial hydraulic lock.
Slip the plug out and crank the engine watch for fuel blowing out the plug hole.

If no fuel comes out adjust the valve lash.
If fuel blows out clean / replace the float needle & seat

bertsmobile1 said:

:welcome:

The video is a classic no compression release situation.

It can also be a partial hydraulic lock.
Slip the plug out and crank the engine watch for fuel blowing out the plug hole.

If no fuel comes out adjust the valve lash.
If fuel blows out clean / replace the float needle & seat

Click to expand...

Hi bertsmobile1, thanks so much for the reply. I pulled the plug and placed a finger over the hole and felt some air blowing out, smells like fuel so I would assume some fuel is blowing out too (not a ton, but again I'm not sure how much should be coming out). When you say clean/replace the float needle, can you direct me as to where that is or what I should be looking for? I'm slightly mechanically inclined but not a ton. Thanks again.

Ericbss7 said:

Hi bertsmobile1, thanks so much for the reply. I pulled the plug and placed a finger over the hole and felt some air blowing out, smells like fuel so I would assume some fuel is blowing out too (not a ton, but again I'm not sure how much should be coming out). When you say clean/replace the float needle, can you direct me as to where that is or what I should be looking for? I'm slightly mechanically inclined but not a ton. Thanks again.

Click to expand...

Are you referring to the carburetor float?

Well that is good news.
A hydraulic lock will blow visible liquid out of the plug hole.
So now it is a lot easier.
Start by adjusting the valve lash.
If you have no idea go on you tube, search " Taryl fixes all- valve adjusting"
You will need to buy a valve cover gasket, but a couple they are only a few bucks and so much quicker than scraping off old sealer.
I use axel grease on the engine side & hylomar on the cover side so it sticks to the cover and strips of clean.
You will need some feeler gauges and some torx drivers to do the job.
Takes about 10 minutes + cleaning time.

bertsmobile1 said:

Well that is good news.
A hydraulic lock will blow visible liquid out of the plug hole.
So now it is a lot easier.
Start by adjusting the valve lash.
If you have no idea go on you tube, search " Taryl fixes all- valve adjusting"
You will need to buy a valve cover gasket, but a couple they are only a few bucks and so much quicker than scraping off old sealer.
I use axel grease on the engine side & hylomar on the cover side so it sticks to the cover and strips of clean.
You will need some feeler gauges and some torx drivers to do the job.
Takes about 10 minutes + cleaning time.

Click to expand...

Perfect. I pulled the valve cover and my top valve certainly appears to have way more wiggle than it should. The video was helpful too (and provided some comic relief). I'll order the parts today and post updates when I have them. Thanks again for the help! Hopefully this takes care of it.

A very old teaching trick.
Pack your lesson with stupidity and the recipiant is relaxed and will retain a lot more than just a talk & chalk approach.

bertsmobile1 said:

A very old teaching trick.
Pack your lesson with stupidity and the recipiant is relaxed and will retain a lot more than just a talk & chalk approach.

Click to expand...

So I was able to get a new gasket today (a local Sears had it in stock). I adjusted the valves, both were very out of whack. I turned the key and it started, running a bit haywire (headlights pulsing). I lowered the throttle and when I did the mower shut off completely. Tried to restart and now it's acting the same way it did pre-valve adjustment. I pulled the valve cover again and both valves are still looking good (set at 0.004). Not sure why it reverted to this behavior when the valves seem to be ok.

Pull the cover off and slowly rotate the engine with a pencil down the plug hole.
The inlet should open at TDC , close near BDC then reopen just a touch just before tdc ( auto decompression ).
If not you might need a new cam.

bertsmobile1 said:

Pull the cover off and slowly rotate the engine with a pencil down the plug hole.
The inlet should open at TDC , close near BDC then reopen just a touch just before tdc ( auto decompression ).
If not you might need a new cam.

Click to expand...

So I went to adjust the valves again, as I don't think I had them in the right position the first time I did it. Right as I was about to adjust them, I noticed that the top (intake) valve didn't have the same little metal cylinder (not sure what the proper name is) that the bottom (exhaust) valve had that the rocker arm comes into contact with (I circled them in this picture http://postimg.org/image/onepi5q0b/). I'm assuming that both valves should have this piece, not just the exhaust valve? The intake valve was very loose when I first looked at it, and it wouldn't shock me in the least if that part fell off somewhere along be way. Can you tell me what that piece is called, or better yet, point it out in this diagram? Having a hard time identifying it. Thanks again for all the help.

http://www.partselect.com/Models/31...=5&mfg=Briggs and Stratton&Type=Engine&Mark=5

They are called lash caps .
Good news is they are not expensive
bad news is you have to find where the old one went
as it can do big damage inside the engine.

Welcome to the small engine tango cha cha cha

bertsmobile1 said:

They are called lash caps .
Good news is they are not expensive
bad news is you have to find where the old one went
as it can do big damage inside the engine.

Welcome to the small engine tango cha cha cha

Click to expand...

Well...adjusted the valves again, and it started and ran well. The I put the blower housing back on, and heard a wicked shredding sound. Turned it off. Found shards of plastic everywhere. The flywheel fan got shredded somehow...can't make it up. I'm thinking the flywheel screen must have been bent or something. Anyways, ordered a new fan and screen. The saga continues....just when I think I'm done. Anyways...thanks for all the help up to this point. Seems like the valves were the main issue.