Briggs & Stratton 575EX with loud bang after 4 seconds switch off

[Reiner]

Hi,
got this 575EX lawn mower from new a couple of years ago. Easy starter until recently.
When engine is cold it starts at the first or second pull and runs fine.
After cutting one box full of grass when switched off it develops a very loud bang after 4 seconds ( engine not turning for 4 seconds ).
After that, it won't start for several minutes until engine is cool again.
Tried E5 fuel even with additives but no change.
But then, on the odd day it runs perfect with out any above symptoms.
Any ideas?

 

[mechanic mark]

Post model xxxxxx, type xxxx, trim xx, code xxxxxxxx, from engine. thanks Mark
Let engine idle for 30 seconds before shutting down.
Adjust valves with engine cold per specs in Operators Manual.

b&s tune-up kit 84002441 - Google Search

Pick up tune-up kit B&S OEM Part # 84002441 & install.

 

[Reiner]

Hi Mark,
cut a big lawn yesterday and let it idle for 30 seconds before shutting off - NO bang.
But unable to restart for about 5-10 minutes again!
It's a 140 cc Briggs & Stratton engine.
I will check the codes later.

Reiner

 

[Reiner]

Hi,
the details are as follow:
Self propelled petrol lawnmower Gardenline
140 cm3
2900 min
2.1 kW
Modell number - PLU 82061
Date 03/2018
Serial number - 08520

Info:
new engine oil, air filter and Briggs & Stratton spark plug make no difference at all.
After first full collector box it has the bang and won't start for 3-5 minutes.
Starts hesitantly after that time.
E5 fuel is used.
If the engine is idle for 30 seconds no bang but still unable to start for 5 minutes or so.

 

[StarTech]

Probably the electronics in the coil pack overheating and going bonkers. Try replacing the coil with a known good one. Should be lots engines out on push mower with bent crankshafts in the local mower boneyard.

Would not hurt to check for a mouse under the shroud first.

 

[mechanic mark]

Results

www.briggsandstratton.com

Read through Operators Manual above, adjust valves .004"- .008",

HOW TO ADJUST VALVES B&S 140cc engine - Google Search

Briggs & Stratton Kit-Carb Overhaul 594636

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www.sepw.com

B&S OEM Carburetor Overhaul Kit for your engine, pick up a bottle of Star Tron Fuel Treatment & follow directions on bottle. See fuel recommendations page 6 in Operators Manual.

 

[Midnight_Rider]

Have you tried using non E gasoline yet ??

 

[TiIngot]

I am reading a lot of these hard starting, backfire issues today and since I just solved by problem I am throwing this out there.

My final solution was solved with a new $2.18 key in the flywheel. Old one was sheared putting timing off 1/8". New key, no more problem. My issue was further complicated because the tractor came to me not running, with "multiple" problems and no service history.