John Deere 400

[ricku55]

My John Deere 400 tractor wants to spit, sputter and backfires when under a load. Took the carburetor off and clean it and it started doing it again. Would a weak battery do it? or and bad needle and set in the carburetor do it?

 

[bruceatlam]

I see that nobody has responded. So here goes, a bad needle could possibly cause the problem. I doubt that a weak battery could. If I were in your shoes, I would buy a new carb ---- I've never had any luck cleaning them.

 

[oldnslo]

Rick,
Needle and seat should be inexpensive components and are wear items. I would probably try them first.

I had an old 112 with a Kohler engine where the ignition coil went bad and acted like this. Take the coil off and test it everything seemed fine. I found this by connecting a timing light to the plug wire and watching for spark. Was challenge to see since running at higher RPMs the light just flickers. My would idle just fine but would not accelerate when this was happening.

 

[grandpajay]

The Kohler in the 400 tends to be kind of hard on condensers. Any older GM replacement will work-doesn't need to be Deere and if a NAPA is closer than a Kohler dealer. It's less than a $10 try. I try to start with the cheapest possible fixes first. Coils don't last forever, either. To test the condenser, loosen the wire connection. Then while running pull the wire off. If nothing changes you need a new condenser. Maybe use an insulated handle on an needle nose pliers to avoid bothering your pacemaker.

 

[Richard001]

Have you replaced the spark plug?

The compression pressure goes way up under full throttle, so a weak or bad plug will start to misfire under load.

Richard

 

[ricku55]

Thanks for the info on my 400 JD. I order a needle and seat for it and will try that first. I will let you know how it turns out! Thanks again!

 

[ricku55]

Sorry for the late reply on my John Deere 400 lawn tractor issue. I put in a new needle and seat, and new spark plugs. It still runs the same! Both cylinders are firing, but when I pull my left side plug wire, the engine has more misfire than when I pull the right side (when I take pull off the plug wires one at a time). Is there such a thing as a weak coil that could cause it? I changed plug wires too. It runs fine on an idle. It seems like it could be a fuel issue yet to me, but I think I might need to take a compression test? Thanks for your help.

 

[ricku55]

I will be trying the condenser next. Thanks

 

[Amvcane]

If you haven’t done so yet, I would make sure your fuel system is functioning properly. No restrictions, clogged pickup, or fuel pump issues.