871 random shuts off

Tiger Joe

Member
This happened twice yesterday, the only common denominator to the situation is that is happened while I was brush hogging. This is the first major workout for my 871 since I have owned it.

The general description is tractor is driving along just fine, all of the sudden it starts losing power. Shuts down exactly like you turned the key off.

Here are the two scenarios that happened yesterday:

1- mowing a field after approximately 45 minutes. shifted up a gear to mow a straight away. It was a bit bumpier than I thought and seemed like the tractor was losing power. I hurried to shut the PTO off and the rpms were dropping. I throttled down to idle and managed to keep it running. I shut it off and it dieseled a bit.

I got off, walked over to talk to my dad and explain it to him. He said try pulling it in the shade. I walked over and it started fine and pulled in the shade. let it sit for 20-30 minutes and it started and mowed fine- until the 2nd time:

2- I started mowing again, everything is going fine. probably 20-30 minutes later- There is a narrow trail we mow that you have to back down then pull out of. I'm backing down the trail when rpms start dropping, this time I cant save it and it just shuts off. no dieseling this time. it sounded just like you turned the key off. So I immediately thought I bumped the key with my leg so check. try to restart. It spins but no fire. I hop off, walk out to tell dad I'm fine tractor just quit. chat for maybe 5 min. walk back in the trail, check tractor over best I can with no light. I notice the wire from coil to distributor has a crack in the insulation. I wiggle it a bit, turn on key and it starts.

We were just about done anyway so I quit mowing and drove out of the woods. the rest of the day it ran fine without issue. I shut it off prolly 5-6 times and it restarted without issue each time.

When I got home I pulled the wire and checked for continuity. It checked out ok, but I decided to replace it anyway.

my initial thoughts are it is spark related, since it does not sputter but just dies abruptly. I just gave it a tune up last week. points, condenser and rotor were all nearly new. I set gap. put on a new cap, plugs and wires.

I want to check the key switch tonight for possible loose wires. My only other thought is the coil- though this will get replaced anyway if I swap to 12 volts.

any thoughts are appreciated
 
Symptoms are similar (not necessarily identical) to the vintage Ford tractor ignition switch gremlin.

Next time you plan to use if for an hour or more, short out the ignition switch with a jumper wire. If the problem goes away, replace the ignition switch.

Dean
 
I've had so many replacement ignition key switch failures that I changed to using a toggle switch. Problem solved.
 
well think I found my issue. Its quite a strange one too!

When I painted the tractor two weeks ago, apparently a bit of red paint dripped through the dash and landed EXACTLY on the ignition side of the distribution block. looks like the paint got in between all of the terminals and was causing the power to short out.

couldn't do that again if I tried.
 

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