Outdoor Power Equipment and Small Engines - no mower lawn mower (part 1 and 2 merged)

This is a fantastic web site. Like having trusted friends
to turn to with my problems which are many because I
never have owners manuals to refer to since all my tools
and machines have been purchased second hand or even
farther down the food chain. Todays problem is my MTD
Yard Machines mulching mower which doesn't because
cover plate has been removed. It has a Briggs & Stratton
4.0 HP Quattro engine that was running fine in the front
yard. Then I shut it down to walk it around to the back
yard and it started just fine in the back yard and I made
a few cuts before it started to lose power and puff black
smoke. It doesn't have enough power to cut and at idle
it hunts. Drained and cleaned gas tank and put in fresh gas,
put in new air filter and another spark plug as the old one
is covered in black soot, now new one is too. Help!

Hello safetytube!

Black smoke indicates too much fuel being burned. There seems to be a carburetor issue here. What are the engine numbers?

The Quatro will be the "Classic-style" engine. First, check to be sure the foam air filter is not plugged (too much oil OR grass debris). If not, and maybe even so, you may need to do a carburetor recon. For the little time and effort on these engines, it would be worth the work to do just this.

There is a sticker on the back of the deck with these numbers.
model: 11a-084c062 serial# 1e049b21736
Thanks guys, I appreciate the help, grass is getting real tall.

Owners manual here, http://manuals.mtdproducts.com/mtd/manuals/770-10108.PDF

If you get the briggs #'s off of the shroud u can use them here http://www.briggsandstratton.com/display/router.asp?DocID=64103

The owners manual shows that both Tecumseh and Briggs engines were used on that mower so it does not list the engine part #

These numbers were on the shroud.
Model 10a902
Type 2189e1
Code 99042754

I agree with Puey61. I get to reading these post so quickly that I miss the details sometimes. The Quattro has a foam air filter that may be in need of a good cleaning as suggested. If that doesn't do the trick, you may have to clean the carb and replace the diaphragm.

I had a run of these come thru a few weeks ago, all had the same problem. On the diaphram one of the valves is near the edge leaving a thin area to seal. The carb base is made of type of plastic and no doubt will swell and compress more with temp changes. The mounting screws were also "just" snug. All the diaphrams had sucked in and put a crease in the thin area requiring replacement.
Briggs # 495770

Thanks for your time and your help guys. I fired it up and it
still isn't right but I ran it until it ran out of gas. A minute before
the gas was gone it started running like new. This hapened
three times. It usually needs only one refill to cut front and
back yards. But why does it run so good just before the gas
is gone? It wouldn't start again until I cleaned the thick black
soot from the spark plug but I've been doing that ever since it
started running so bad. I took the muffler off and blew threw
it and it doesn't seem to be clogged but of course it has a
coat of black soot. Replaced air filter and oiled according to
instructions. Changed crankcase oil - SAE30 exactly to full mark.
Replaced spark plug -Champion RJ19LM gapped at .030.
Tightened phillips head screws under carburetor.
My wife bought the last can of gas for this mower and didn't
buy it at the station where I usually buy gas. Could this be
the problem?

Safetytube,

I merged this thread with the old one, so we can keep track of what's going on. Use the reply button instead of starting a new thread to keep continuity of the discussion.

As far as the problem with the mower...you need to replace the carb diaphragm. It runs best just before it runs out of gas because it's getting too much gas all the rest of the time. When it runs out of gas, the engine gets less gas for a moment before it dies. That's what the engine needs, is less gas.

You have a fuel dumping situation. This likely is caused by the primer check valve (ball) not seating properly. While you have the carb off to replace the diaphragm - Briggs part # 495770 - be sure to replace the check valve, part # 494409 behind the primer bulb, part # 694394. These three items should get you back up and running (with good fuel economy)!!! Refer to Azis link to the Briggs site for a look at the parts breakdown of your engine and this should help you make the repair.

Finally got the Briggs parts needed.
#495770 diaphram
#494409 check valve
#694394 primer bulb
It looks like the primer bulb is smaller than the old one. Could be my eyes.
But I can't get the old one off the carb. Whats the trick to removing the
old bulb? Anxiously waiting your answer as the grass is getting real tall
again.

On the sides of the housing that the primer is in, there are two tabs. You push these in while pulling the primer put. These tabs are what locks the primer in place. Once out, just pull the retaining ring off the old primer and slip it over the new one and reinstall.

Thank you, Cheese, Puey61, Azis.
No mower lawn mower is running like a new machine today.
I wouldn't have attempted this repair without your advice.
The grass is real short today.