Deere 100 Series

[FPMotorsports]

Afternoon folks, hows everyone been running?

Recently just came across a john deere las100 with about 600 hours on it. It starts fine, runs great for about 15-20 minutes than seems to lose power. It doesnt surge, and it apparently only started happening after a few cuts in the spring.

Any ideas of what this issue may be?! I have yet to do ANYTHING to it, i will start in the morning (to damn hot right now 36 celcius)

What troubleshooting steps would you take?

Any and all recommendations are greatly appreciated!

 

[reynoldston]

John Deere made a model 100 in the mid 70's with a 8 HP Briggs. Is that what a las100 is. Also when you say losing power just what do you mean by that, starts to miss fire or just dies like its running out of fuel?

 

[FPMotorsports]

https://www.deere.com/en_US/product...wers/lawn_tractors/100_series/100_series.page

I personally havent ran it yet, ill do that in the morning. A friend just told me thats the issue. Starts normal, runs fine, doesnt surge or pulsate so to speak. Ill obviously run through all the normal stuff tomorrow, filters, plugs, etc.

Ill also get an exact model number and a better idea of what happens after 20 minutes of run time!

 

[bertsmobile1]

Old mower, worn rings with oval bore = loss of power when hot.
Old condenser ignition does the same when the cap is pasts it's use by date & gets hot.
electronic ignitions can go the same way.

 

[reynoldston]

https://www.deere.com/en_US/product...wers/lawn_tractors/100_series/100_series.page

I personally havent ran it yet, ill do that in the morning. A friend just told me thats the issue. Starts normal, runs fine, doesnt surge or pulsate so to speak. Ill obviously run through all the normal stuff tomorrow, filters, plugs, etc.

Ill also get an exact model number and a better idea of what happens after 20 minutes of run time!

So you are saying its a newer John Deere in the 100 series not a John Deere Model 100. It helps to know what year, model and engine John Deere you have with the information as to just what its doing.

 

[FPMotorsports]

Yezzir, LA125, running a 21 hp briggs.

Thank you for the suggestions Bert!

I took a look at it yesterday, theres lots of trimmings and things floating around the gas tank, the fuel filter is crammed full of things. The air filter and plugs were gross. The carb needs a good soak too. I will try these quick easy fixes first, than run it again for an extended period in order to see if there is still power loss. At which point I will look into the recommendations Bert has put forward.

 

[FPMotorsports]

UPDATE: Okay, so over the weekend I put in 2 new plugs, properly gaped. New air filters, new fuel filter (it was disgusting) I drained all the gas in the tank (there was a ton of leafs and things in there) Cleaned it, put fresh gas in. Did oil and oil filter. Cleaned all fins, cleaned everyone, checked hole in gas cap. Its certainly idling much better, it sounds better and has a bit more GO in it when just driving around but the issue from previous is still there....

What happens is that after 15-20 minutes of cutting, (actually using the deck, or under "load" so to speak) the motor loses almost all power. Does not shut off, but reverse becomes super slow mode reverse, and forward the same thing.

Any recommendations?

 

[bertsmobile1]

Just to make sure we are singing from the same song sheet.
Does the mower travel slow or dose the engine run slow ?

If it seems to be mosty ground speed then you are looking at low oil in the box or air in the box .

If it is engine then check you are firing on both cylinders.
If you can also try activating the choke partially.
If the engine runs better with a little choke you still have a fuel delivery problem.
Some times it takes multiple cleans to get all the crud out , particularly f you do not remove the tank completely and clean the outlet from the tank.
JD put pre filters into the tank on a lot of models and yours could be one of them.

Do the cheap & easy first.

 

[FPMotorsports]

The rpm and everything seems fine, starts up just fine no problem from cold. Runs well. sounds great, runs on with the choke on run. But it moves slow, and than after cutting a bit just travels slow.

 

[reynoldston]

LA120 John Deere with a Brigg & Stratton engine that moves slow. It has a Tuff Torq T40 hydrostatic transmission. The very first thing I would check is the transmission linkage then make sure the drive belt is OK. As I recall the trans drive pulley tens to strip out on that model transmission but then it wouldn't move at all.