# John Deere LA115 Won't start without jumping



## kcarlson30 (Sep 14, 2020)

Hi All -

I'm new to this forum and hoping to get some assistance. I have a JD LA115 riding lawnmower. It was working fine and I got off to move a hose and went to get back on and it wouldn't start. If I charge the battery, it will start again, but then after a little bit and I shut it off, it won't start again. 

Any thoughts on what this might be?


----------



## DexterII (Jul 14, 2010)

Welcome. What kind of shape are the battery cables in? If the connections are corroded the first thing I would do is remove, clean, and reinstall them, and see how it goes. If they look in pretty good shape it sounds like the battery is bad. But it's only X months old? Doesn't matter. Batteries can go bad regardless of age. And putting a volt meter on them tells you close to nothing, so charge it up, disconnect the cables, remove the battery, and take it to your nearest auto parts store or full service lawn and garden center and ask them to load test it. Load testing is quick and easy, and does just that, puts a load on the battery so they can see what kind of shape it's in. If it happens that the battery test good, well, could be any number of things, bad ground, bad charging system, etc., so get the battery tested and let us know how that goes.


----------



## SeniorSitizen (Sep 10, 2012)

A wealth of information from Dexter II.


Won't *start* or won't *crank*. Knowing which often lessens the guesses of what could be wrong. 



No crank symptom -- sometimes a low battery or corroded battery terminals and or cable ends can be detected by grasping the carburetor bowl when turning the key to start. Those that have the fuel solenoid gas shut off at the carburetor will need X number of volts to open that solenoid valve. If we grasp the carburetor bowl we can usually feel the valve shift to open and unless a trucker is close by on his Jake Brake we can hear the audible click. 



Those with that carb. solenoid valve will also die while mowing because of a low battery, not because the spark plugs need the volts but because of the aforementioned gas solenoid valve closing because of low voltage.






Edit: Edit:


----------



## bob22 (May 28, 2008)

Saw a YouTube video on a rider mower that had the charging system wiring burnt out due to jump starting. Don't ask why but they guy fixing it said it happens a lot and it wasn't a homeowner fixit guy.


----------



## raylo32 (Nov 25, 2006)

One possible issue if the engines are anything like on Craftsman riding mowers is a broken compression release mechanism. This can make it very difficult to turn the engine over fast enough to start but it can still start sometimes, especially with a battery fresh off a charger or with a jump from a running engine pumping out max volts. Hard to tell from your description exactly how it is behaving but this is something to check.


----------



## lenaitch (Feb 10, 2014)

Yes - won't crank or won't start?

Could also be one of the safety switches (pto, seat, transmission, etc.).

I had a chronic problem with my old JD as well as my 'real' tractor (New Holland). Both would often crank but not start, inconsistently and got worse over time. Turned out it was small voltage drops caused by dirt in the multiple safety switches in the starter primary side that, added up, limited the power to the starter solenoid. I put a relay in both - solved the problem.


----------



## surferdude2 (Nov 21, 2019)

raylo32 said:


> One possible issue if the engines are anything like on Craftsman riding mowers is a broken compression release mechanism. This can make it very difficult to turn the engine over fast enough to start but it can still start sometimes, especially with a battery fresh off a charger or with a jump from a running engine pumping out max volts. Hard to tell from your description exactly how it is behaving but this is something to check.


 Amen, A lot of batteries get replaced needlessly when that happens. All it takes is for the exhaust valve lash being a tad too loose. I've seen mechanics that worked on autos and trucks all their lives that have a hard time believing that valve adjustment will prevent an engine from cranking over properly. Little engines are a different game altogether.

I can't afford a JD but here's how Briggs & Stratton does theirs


----------



## raylo32 (Nov 25, 2006)

LOL... I just replaced a cam exactly like this on a Craftsman rider with a B&S engine a couple months ago (see also the thread in mowers forum: https://www.diychatroom.com/f106/latest-last-2014-craftsman-lt2000-mower-issue-692029/) that had been very hard starting for at least a year... after assuring my friends that it was just a weak battery and I have worked on cars all my life yada, yada, yada. Wasted a battery for sure. But saved a lot of $ doing the cam myself once I figured it out.

Crazy how fragile that compression release mechanism is. Broken bits of metal all over inside the crankcase. I don't know if other mfgs compression releases use a similar design or suffer from routine failures like the B&S units... but definitely something to consider here if he has a slow crank scenario.

And yes you are correct about the valve lash. It is an easy adjustment but if the the lash is off so that the compression release doesn't crack that intake valve open at TDC you will have the same problem as if it is broken. You can spin the motor by hand (with spark plug removed) as a check to observe whether the release is working. The intake valve will momentarily crack open just a tad...



surferdude2 said:


> Amen, A lot of batteries get replaced needlessly when that happens. All it takes is for the exhaust valve lash being a tad too loose. I've seen mechanics that worked on autos and trucks all their lives that have a hard time believing that valve adjustment will prevent an engine from cranking over properly. Little engines are a different game altogether.
> 
> I can't afford a JD but here's how Briggs & Stratton does theirs Compression Release.


----------



## surferdude2 (Nov 21, 2019)

:biggrin2: I'll laugh with you, not at you because that little trick device has fooled lots of folks and sold many a battery. :biggrin2:

One correction to your outline, it's the exhaust valve that gets lifted during the compression stroke to provide the relief for easier cranking.

BTW, If you didn't stumble across this corny video linked below, you may get a kick out of it. Be patient and put up with the corn ball humor... it's obvious that this guy has been inside a few B&S motors.

Best regards, SD2


----------



## raylo32 (Nov 25, 2006)

I just did this job and on my B&S 19hp Intek engine and the compression release definitely operates on the intake valve. It really could have been either one but they chose the intake for some reason. And it really doesn't matter from a repair perspective because the cam goes in only one way.


----------



## surferdude2 (Nov 21, 2019)

raylo32 said:


> I just did this job and on my B&S 19hp Intek engine and the compression release definitely operates on the intake valve. It really could have been either one but they chose the intake for some reason. And it really doesn't matter from a repair perspective because the cam goes in only one way.


Well I'll be dogged... That's hard to believe. Seems to me like blowing back through the intake/carburetor on the compression stroke would traumatize the carb and cause some gas to get blown back on the air filter.

I will add that given the way they have the block ported, it's not easy to tell which valve is which. Just sayin' :wink2:


----------



## raylo32 (Nov 25, 2006)

Really not much blow back. It only cracks open a tiny amount for a few degrees of crank rotation, and only for a couple of rotations after which centrifugal force takes it out of play.



surferdude2 said:


> Well I'll be dogged... That's hard to believe. Seems to me like blowing back through the intake/carburetor on the compression stroke would traumatize the carb and cause some gas to get blown back on the air filter.
> 
> I will add that given the way they have the block ported, it's not easy to tell which valve is which. Just sayin' :wink2:


----------



## SeniorSitizen (Sep 10, 2012)

raylo32 said:


> the compression release definitely operates on the intake valve. It really could have been either one but they chose the intake for some reason.


Maybe the tree hugging politicians objected to blowing a squirt of unburned gas out the exhaust and were attempting to re-cycle it.:vs_laugh:


----------

