Jon Deere LX 188 bogs down

[nettieabcd]

Hi there,
I have an older JD LX 188 that has been a wonderful machine until recently. What happens is that it starts and runs great until I start mowing. Then after about 5 minutes it starts to mis-fire and eventually stalls. It will sart again fully choked but then go only about 10 feet before stalling again. I have replaced the spark plugs, installed a new carberautor, cleaned the fuel lines, checked the fuel pump, 2 mechanics have looked at and it still does the same thing. It will run just fine until it is under a load, a feature of the problem that I can't get the mechanics to understand. Could it be coil/wires?
thanks for you help.

 

[DaveTN]

Hi there,
I have an older JD LX 188 that has been a wonderful machine until recently. What happens is that it starts and runs great until I start mowing. Then after about 5 minutes it starts to mis-fire and eventually stalls. It will sart again fully choked but then go only about 10 feet before stalling again. I have replaced the spark plugs, installed a new carberautor, cleaned the fuel lines, checked the fuel pump, 2 mechanics have looked at and it still does the same thing. It will run just fine until it is under a load, a feature of the problem that I can't get the mechanics to understand. Could it be coil/wires?
thanks for you help.

My friend has an old LGT FORD 14HP Cast Iron Kohler engine in it. His did basically the same. We went thru the carburetor 6 times or more. It would mow great, even under load, then suddenly sputter, and nearly die. Had to disengage the blades and sputter back on 3/4 choke. Even then it would die and have to sit several minutes and crank it again. The problem wasn't in the carb, or the fuel line, but in the "L" shaped inlet from fuel ine into carburetor. It would occasionally vibrate some flake of dirt or something over the inlet and starve the engine for fuel. After using a wire and carb cleaner with a wand and spraying it out good, it got good flow and runs like a charm now! Assuming it's NOT that...having it run on choke sounds to me like a fuel starvation problem. When it sputters out like that again, quickly take the float bowl off and see how much fuel is IN the bowl and if there are any sediments etc. Note in particular the FLOW of fuel. Is it in sufficient quantity, as in a small stream? Or is it drip, drip, like an old faucet? You MUST have a flow of gas to run a mower under load. I've seen them run on a drip but only idling and then may die. Could possibly be a coil getting hot and getting too much resistance to fire the plug, in which case you'd have to replace the coil. If you could borrow a good coil, say from one of your mechanics and test it again that would eliminate the coil problem. Could also be an intermittent grounding of the switch/kill wire. Maybe rubbing on something and grounding out the coil, but that wouldn't account for it running on CHOKE. Give us an update and I'll ponder on it further.

 

[SONOFADOCKER]

Have you ever taken the head off to clean the carbon off the piston head and valve heads ?
When carbon gets hot fuel ignites before compression stroke .... Loss of power ...

 

[MNBen]

What engine is on the JD?

I am having the same issues with my 12.5 Briggs. cleaning carb several times and a new carb kit did not help. I swapped the coil and that did not help. I do have a stripped spark plug hole that probably contributes to mine. I will be swapping out the head with a spare I have and will clean the piston to see if that helps.

I subscribed to this thread because I hope you let us know what fixed the issue.

MNBen

 

[nettieabcd]

Well, i have spent about $600 dollars with 4 trips to various mechanics and the mower still bogs down when hot. I hate to scrap it for what is probably an easy fix for someone who knows what they are doing. I mean, it's a Deere, an LX188,etc. surely there is a mechanic who would know what to do.

 

[Glenn300]

only three areas to consider fuel ignition and compression

On the fuel area if the wire works loose on the fuel cutoff it will give trouble and not let fuel flow
through the carburetor -this has been an issue on that Kawasaki engine. I rewired a new wire
from ignition swith to the cut off and repaired one engine that way. The fuel line from
the tank to to the filter can be checked and from the fuel filter to the fuel pump . I f remove the
line from the fuel pump going to carb and crank over the engine and adequate fuel flows then
it only leaves the possibility of carburetor fuel flow. Also on the LX188 engine the carb will have
a tendency to run rich under idle and smooth out under load. In fact if you adjust it to good idle
I have seen on this eninge it bog down under load. try about 1/4 more on rich setting than
is listed in the service bulletins and see it that helps

As to compression - make sure the valves are adjusted correctly and there is adequate
compression for the engine to operate (if adequate) - then most likely it is an
ignition problem . If the compression reading was high it would indicate excessive carbon build up
in the heads- but rare on this model engine

On the ignition - first change the plugs - I have seen good looking plugs misfire. I have
found the Lx188 runs better with NGK plugs. Second ensure that the flywheekl is not loose or
it will throw off timing. Also make sure the exciter coils on the outside of the flywheel are
clean and tightly connected to the casting of the engine. Remove the plugs and lay against
the frame of the engine and crank engine over and see if have blue spark if so iginition proably in
good shape but like I said a good looking plug can misfire under compression load.
Also with any engine an ignition coil can break down and misfire when it is hot but a basic check of
the ohms of the primary to the seconday can pinpoint internal wiring problems in the coil.

All of this assumes you have a good battery and tight connections and properly operating safety
switches that are not causing problems. A weak battery will cause weak fire and a loose
safety swith with cause one to misfire . Also the oil pressure switch on some models with
shut down ignition if have low oil pressure so make sure the wire to the oil pressure sending unit
is tight.
I have rebuilt a few of the LX 188 engines and most of the problems are fuel related
to defective carburetor or fuel shut off

 

[nettieabcd]

thanks to all of you for your input. This thing is driving me nuts. I will fiddle with it, it starts and runs great until it gets hot, then bogs down. But I will study all of your posts and see if I can remedy this situation once I have time to really tear into the machine.

 

[Glenn300]

according to the tech manual for Kawasaki liquid cool the following is a comprehensive list of
reasons for engine loosing power (from tech maual john deere lx188)

weak or fualty spark plug
Faulty high tension leads
Faulty ignition modules
fualty iginion coil
faulyt pulser coil
contaminated fuel
defective fuel pump
Air drawn in from defective fuel hose
clogged fuel filter
fuel tank vent line clogged
vapor lock
poor compression
cylinder head loose
warped or burn valves
improper valve clearance
warped cylkinder head
broken valve spring
defective head gasket
improprer oil level
carb out of adjustment
carbon deposit in exaust pipe or muffler
carbon deposit in combustion chamber

Well a lot of stuff but I would be on defective ignition module of defective exciter coil
these are all parts that will change operating characteristics when they heat up
I would bet you have an ignition problem but between this posting and the last posting
I think you have enough to consider all possibilities.
Just remember go through the process of elmination if all else fails.

Glenn300

 

[Hank Koster]

I have a problem similar to this with my LX-188. Mine will start fine and mow fine, but then it will act like it's starved for fuel and run very poorly for about 5 or 10 minutes. If I just sit with it gasping for life for a few minutes, it will clear itself and run great for another 10 minutes before it stumbles again for 5 or 10 minutes. It keeps going through these cycles (run great, gasp, run great, gasp), which tells me it's not an ignition or valve problem. Does this sound like a junky carburetor to anyone? Both coils and the fuel pump have been replaced. I've taken the fuel line off and inspected it and it looks fine.

Should the fuel filter always be mostly full? Sometimes mine is completely empty, even after replacing the fuel pump, but whether it's full or empty doesn't seem to match up with how well the engine is running.

Any advice is greatly appreciated!!!

 

[Fish]

Sounds like you just need to drain all of the crap and water out of your carb.