John Deere propane backfiring like crazy

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BlondeD
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John Deere propane backfiring like crazy

Post by BlondeD » Sat Sep 01, 2018 7:47 am

.........my old...usually reliable.... propane tractor I use for spray rig duty has suddenly developed a bad backfiring issue, loss of power and just barely chugging along. And most of the old mechanics around here that know about propane setups have passed on. Anybody here with some hints.?????
Thanks

hurleyjd
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Re: John Deere propane backfiring like crazy

Post by hurleyjd » Sat Sep 01, 2018 8:06 am

Check the points in the distributor. The points may be about gone.

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Nesikep
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Re: John Deere propane backfiring like crazy

Post by Nesikep » Sat Sep 01, 2018 9:37 am

what he said, check the entire ignition system. bad plug wires and spark plugs too.. running it at night may help you see where something is arcing
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msplmtneer
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Re: John Deere propane backfiring like crazy

Post by msplmtneer » Sat Sep 01, 2018 11:23 am

Also check the timing :tiphat:
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Re: John Deere propane backfiring like crazy

Post by snoopdog » Sun Sep 02, 2018 4:36 am

Sounds exactly like the points .
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Re: John Deere propane backfiring like crazy

Post by Texasmark » Sat Sep 08, 2018 1:20 pm

Backfiring is the intake valve being open during the combustion stroke......Check compression, easiest and quickest way to determine if you have a valve problem. Could be bad seating surface due to carbon or sticking in the valve guide, not releasing when the tappet backs off it, broken valve spring, bent shaft, tappet out of adjustment.....too tight.

Or, with the LP, the regulator is loading too much gas into the intake to be consumed and prematurely ignites on the intake stroke....carbon on the piston glowing would support this theory.

Or timing too fast....ignition occurs before intake valve has closed...points pitted for that one.

All opinions, most based on prior experiences. I had a 196X year model 4020 LP......most temperamental tractor I ever owned and my first JD. Was glad when that sucker put it's knees under somebody elses table.

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