JD engine stops; will restart after 3-5 min. "rest"; need help

[rlhatejd]

1. JD335 runs with mower engaged for about 5 min. to as long as ｽ hr. & then engine stops. Found one plug not firing; found ign. coil primary bad; replaced both ign. coils; both plugs fire now. But, engine stopping symptoms remain.

2. Last season I replaced all fuel lines, cleaned fuel tank, installed new fuel cap, filter & pump. Each of these items was done in stages as opposed to all at same time. Symptoms then were different. Tractor would run for 1 1 ｽ hr. then suddenly engine slowed down & almost quit; disengaged mower, engine kept running rough, then smoothed out; after about 2 minutes, I increased to full throttle & engaged mower; machine ran fine for ｽ - ｾ hr. then started to die again. That痴 when I began replacing filter, fuel pump, various fuel lines and finally line from tank to filter and cleaned tank; did each in individual steps hoping to discover a single component fault.

3. This year symptoms are as described in para. #1. Anyone out there with a 335, or 325, 345 or GX 335, etc. experience para. #1 symptoms & find solution? Need help. Grass is growing. Thanks, Dick.

 

[beenthere]

Sounds fuel related.
I think what I would try (by isolating the fuel tank) would be a secondary fuel supply (aux. tank or fuel can rigged with connection to carb).

Your #3 said symptoms as described in #1. Does that mean you again found one plug not firing and the ign. coil bad?
Or just that it stops when the mower is engaged for 5 min. or ?? (not sure what the symbols mean but look like 1 hour and a half).

If the mower is not engaged, does the engine shut down in the same or similar time frame?

Maybe this is karma for hating jd. lol

 

[rlhatejd]

beenthere: Regarding fuel, I've checked fuel output to ambient from pump outlet & looked good. Installed new pump anyway.
Regarding your questions: I wrote part of #1 incorrectly. Should have written engine runs w/mower engaged & mowing for 5 min, then quits. After waiting 3 - 5 min. engine starts and unit mows for another 5 - 10 min., then quits. The no spark at one plug & subsequent replacement of both ign. coils as described in #2 refers to 2012 problems. During that period, engine would run for an hr. or more, slow down & almost quit. That's when I started at the pump & replaced items like hose, filter, pre-filter hose, then removed & cleaned tank. So everything in the fuel system as been replaced & tank cleaned, new fuel cap installed. Only the carb. and the fuel shutoff valve have been left untouched.

Since there are 4 solid state relays plus resistors, diodes, etc. on the ign. circuit board I wondering if a diodes or capacitor is overheating and activating a relay which in turn grounds the ign. coil circuit. This would shutdown the engine. BTW, I never get any backfiring at engine shutdown. Still perplexed & would like to avoid dealer costs. All they do is R & R parts 'til the machine works. They don't even rebuild carbs any more; they replace them at $550+ labor. I'd like to avoid this. Thanks for your thoughts to date. ~Dick

 

[beenthere]

Thanks for clearing that up.

Looks like that ignition module is about $100 through Deere and $80 on eBay.

 

[rlhatejd]

Actually it's $110.89 fm a JD dealer with PA sales tx. And yes $80 on ebay, free shp'g, no tx. Not a bargain, but 25% off retail is still helpful. Now, will it solve my problem? Diagnostics on these machines can be a nightmare. ~Dick

 

[jessec]

try pushing a pin or needle thru the vent on top of the gas cap. sometimes it gets blocked and won't feed fuel.

 

[beenthere]

Or just loosening the cap to allow air in should be a good test too, if venting seems to be a possibility.

 

[rlhatejd]

Already installed new fuel tank cap; also running with cap partially unscrewed to assure venting.

 

[RetiredCarGuy]

First eliminate the possibility that it is a simple fuel tank cap vent issue.

Sounds like it may be an ignition component failing, after all are heated. The coil is the usual prime culprit. Try to duplicate with a hair dryer blowing hot air on the ignition coil component, and others when the engine is first started from cold. Don't hold too close or too long, as it may cause damage or worse!

 

[rlhatejd]

RetiredCarGuy: I've already eliminated the fuel cap vent as a cause. Also replace both ignition coils, as I found I had no spark at one plug. You have an interesting suggestion re. heating components on the circuit board that control ignition. Since I've already bought a new JD ign. sw./circuit board assembly, I'm going to install it shortly. I will advise this forum of the outcome. Meanwhile, thanks for your suggestions.