No compression when I pull the cord on my lawnmower Briggs and Stratton. What do I look for and how do I fix it?

Back to basics, is the fuel in the tank good?( fill with fresh fuel ) does it have a spark at the plug?(remove the plug, earth against the cylinder, is there a spark,if not, replace the spark plug and try again ) does the plug wet with fue lafter pulling?( clean/service carb ) is the spark occuring in the correct place ( flywheel key sheard ) has the engine got good compression?

Check your under side. For grass builtup

did you hit something while mowing the key way between the flywheel and crank shaft might have sheared it will act like the blade is missing pull back on you while pulling the rope

go to replace pull cord follow instruction

sheared timing flywheel key replace it check to see if crankshft bent if throw it away or replace motor

you need a valve spring compresser dont try useing two screw drivers to remove the clip use the valve spring compresser it so much easier

it is a small engine just buy a new one it will be cheaper in the long run and save yourself some trouble

You should be able to Fix this yourself if your a fair garage tinkering mechanic. However...I need the engine and type number off of the engine to get you parts information. The spring is broken in your recoil. It is a matter of removing the air shroud, taking off the pulley / spool and changing the spring.
http://www.ehow.com/video_2328977_how-install-lawn-mower-starter.html

and how to tension the spring:
http://www.ehow.com/video_2328961_how-tension-lawn-mower-starter.html

There are 2 different types of springs used so having your engine model / type number is important so that you can get the right spring. One of the 2 part numbers is: 390066

Thanks for choosing FixYa,
Kelly

Pull the spark plug out and see if it isnt hydro locked. Someone might have overfilled the oil or the carb float may have stuck open and filled the intake with gas!

If the recoil is still stuck you can remove it from the mower and try it without any load on it. Still stuck? The unit might be rusted solid!
You can spray a little penetrating oil into it but be careful.....the oil will soak the pull cord which should be cleaned and degreased immediately following using the penetrating oil.