Greetings Vern... I have came across your issue a few times in my shop and very many times on this forum.......
By the way you explain it It seems like your cam. Either your cam broke Cutting grass and engine running fine at one time, do you have compression ?? No need to pull the head just take the valve cover or covers off and check the rocker arm travel.. See if both are moving the same travel length, could be a valve seat or guide in the head... If you lost your lost your ACR auto comp release on your cam during mowing it should have fell to the sump base with no ill effects to the crank shaft, well most of the time anyway. What do you mean by RUN OFF?? revved up real fast then engine stopped ?? My dad always said a engine won't die on you in the garage and a outboard engine won't go out on you in your driveway it's gonna die on you in the open water somewhere, I am betting a whole .25 cents you have a Briggs on your mower.......
What is your model number ??? and make of the engine ?? BTW it's not your battery or connections.....
Let us know Mon Ami..........
Below is Engine Numbers:
Husqvarna Model YTH2042 42 inch Mower Engind ID
Mower Serial Number: 120710A001193
Briggs & Stratton Engine 20 HP (one Cylinder)
Model 331777 2372
Type G1
Serial No 101102ZD
What do you mean by RUN OFF??
That is another of my tying mistakes. It should have been "started to run ROUGH somewhat like if not getting fuel or choke being applied, then died rather quickly.
I am going to re-check everything again but I have had both push rods out and both look normal. When spark plug is removed, then switch on. both the intake and exhaust valves appear to have the proper movement and travel distance.
There is no apparent lodged item since (turning by hand) there are no apparent stops or lodging against something. Of course, at the points of compression build up, it is harder to turn. This engine appears to have very good(high) compression even though I have not done a metered compression test.
If there is part of the compression release device broke (from the cam shaft gear I assume) then is there a FIX for this without "breaking the engine apart" to replace whatever is broke.
Note: I have two Husqvarna mowers and have gained some helpful experience by a lot of work on the other mower which was considered to be completely non repairable. Thankfully, I did NOT have to separate that engine to get it repaired and working well.
I appreciate your help
My Regards, Vern....