I have a 1969 JD 4020 that was running great until the other day when I was mowing. I noticed it was slowly loosing power. I drove it up to the house and it shut off. I barely got it back started and it would run for about 10 sec. and shut off. The tractor will start and when you give it throttle it will shut off. I blew air back throw the return lines to check for blockage with the fuel cap open and I could hear air blowing in the tank, so I would assume that is not the issue. Any help would be great.
Let us know if your tractor is gas or diesel which will make a world of difference with the diagnosis.
Yes, I see you mentioned return lines so we're talking diesel. This is a classic symptom of a failure of the plastic governor ring inside the injection pump. The junk plugs the return lines leading to pump internal pressure building and engine shutdown. Test by loosening the pump timing cover which allows it to "bleed". If the engine runs okay, that's likely the problem and will require a pump rebuild.
Yes, I see you mentioned return lines so we're talking diesel. This is a classic symptom of a failure of the plastic governor ring inside the injection pump. The junk plugs the return lines leading to pump internal pressure building and engine shutdown. Test by loosening the pump timing cover which allows it to "bleed". If the engine runs okay, that's likely the problem and will require a pump rebuild.
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