Engine JD LA-120 (ROUGH IDLE at low idle setting)

[hetrickw]

Just replaced plugs/fuel filter/air filter. Ran great for about an hour then when in very low idle runs almost rough enough to shut off.
I checked wire connections, plug gaps, air filter again and all correct including PLUG Type & #. Ran fine for (1) hr. Have 98 hours on tractor never adjusted carb or engine settings. Sounds like carb to me, any thoughts? Can anyone point me in the direction of carb settings for this B&S 44.2 (725cc) ?

Thanks in advance!
Bill
(San Antonio)

 

[SeniorCitizen]

With it running rough at low idle, pull the plug wires one at a time to see if one cylinder isn't firing.

 

[hetrickw]

With it running rough at low idle, pull the plug wires one at a time to see if one cylinder isn't firing.

ok, will do & update. Thanks S.C.


Bill

 

[hetrickw]

ok, will do & update. Thanks S.C.


Bill

Just checked it.
I pulled one plug wire still runs about same roughness (feel pulse of electricity on boot), did same to other cylinder and same thing runs about same roughness with pulse of electricity to that boot also. checked plugs & gap again look good. Didn't know a 2 cylinder engine would run on only one cylinder. doesn't appear to be plugs/wires/fire.....im fairly sure.......
have fire to plugs (unless the brand new plug/s are not working).....

I guess I should try another set of plugs to count that out, then onto fuel/air (carb) correct? don't want to mess with carb unless I have to. checked the air intake and filters / pre filter clean no restrictions.. Odds are it's something I did recently .....

thanks in advance for any and all assistance.

Bill

 

[SeniorCitizen]

Rough at low idle but smoother at high speed can be a possible vacuum leak and I suppose with a central located leak it could effect both cylinders depending on intake manifold structure. That's why I suggested one plug wire at a time to determine if only one cyl. was causing the problem. To check for intake gasket leaks a aerosol combustible is sometimes sprayed around gasket and hose areas that may be taking in air at inappropriate locations. Might check that before going into carb settings . I like easy checks first.

 

[motoman]

hetrickw,Feeling pulse thru spk plug boots is not definitive. I think I read JD dealers have coil testers, although they can be bad too. My Intek idles rough if the valves go out of adjustment. I do not knowJD's.

 

[hetrickw]

hetrickw,Feeling pulse thru spk plug boots is not definitive. I think I read JD dealers have coil testers, although they can be bad too. My Intek idles rough if the valves go out of adjustment. I do not knowJD's.


ACTUALLY THE MOWER ENGINE IS SURGING AT LOW TO MID THROTTLE!

Ill pull carb and check it. anyone know trick to check coil pack/s?
If anyone knows, please advise. Ill look back at firing after rule out carb's since its never been pulled.
gas is good, usually run gas dry for winter storage and religiously use ETHANOL TREATMENT IN MY SMALL ENGINES.

THANKS

BILL (san Antonio

 

[Jhon]

Try putting the old plugs back in and see what happens.

 

[hetrickw]

Try putting the old plugs back in and see what happens.

I cleaned the carb.......saw very little in the carb but cleaned out all the passages....put it back together and SHA-BAM........
works like a charm.............thanks all!!!!!!!!!!!!!!!
7 YEARS OF PREMO GAS/WITH ETHANOL TREATMENT/AND PROPER WINTER STORAGE.... AND THE VARNISH FINALLY GOT ME........

HATE CORN ADDED FUEL.............
bill (san Antonio)