Hello,
I got a new lawnmower last year with the Briggs & Stratton 'Guaranteed To Start' GTS 150.  For the first 10 or so mows, it started on the first pull every time.  Then something happened.........
Now, for the past 5-6 mows, it takes 8-15 pulls to start.  It seems like whatever auto-choke mechanism it was using before isn't working properly now.
Can anyone advise?  I'm hoping there's an easy fix.
Thanks!

Please post an engine model # so we can look up parts diagrams.
 
With that said, there should be a small sping atop the carb that pull the choke plate
closed...  If you remove the air filter, engine cold, the choke plate (closest to the filter)
should be closed-  I suspect it's not
 
.

Hi,
Thank you for your response.
 
Engine model #:  093J020166F1
 
See image from behind air filter below:

 

Part #117 is where you have to get to and clean:
 
https://www.jackssmallengines.com/jacks-parts-lookup/manufacturer/briggs-stratton/briggs-stratton-engine/020000-09z999-series/093j00-to-093j99/093j02-0116-f1/carburetor-group 
 
There's some very, very small holes there that MUST BE CLEAN.   Spraying brake cleaner must flow thru
all of them...  
 
It's a common issue with this plastic carb but there's nothing to varnish up.
Pop #117 out GENTLY with a small screw driver.
 
Pay attention to the linkages once the plastic air filter base is removed...
 
Might want to drain and flush the fuel tank of any debris as well.
 
If you can't get it clean, you can buy that lil assembly alone. 
 
 
.

Part #117 is clogged:
 
https://www.jackssmallengines.com/jacks-parts-lookup/manufacturer/briggs-stratton/briggs-stratton-engine/020000-09z999-series/093j00-to-093j99/093j02-0116-f1/carburetor-group
 
Remove the carb, pat attention to linkages.  Get the bowl off, float and needle. That lil assembly
can be popped out GENTLY.  It only goes in one way.
 
Make sure ALL three tubes are clean / clear with brake cleaner.
 
If need be, clamp a wire brush STRAND in a vise grip and gently open up the holes.
 
That entire part is available if you can't get it clean..
 
.

I cleaned the spark plug and it's back to first pull starts again.