620 acts like its running out of gas

bobgrimes

Member
My 56 620 just started missing several beats every o ve in awhile. Acted as if it was running out of fuel. Checked and it has plenty. Sounds like a fuel problem but Im not sure. Any suggestions are appreciated.
 
Take apart the top of the fuel bowl; the system is designed to shut down if oil pressure drops. On a coupkle of occasions I have seen tractors with this system get crud in those veins restricting oil flow and causing the symptoms you describe, one had a timothy bus in the vein. Also the two rubber diaphragms that keep the oil in the veins get bad and begin to deteriorate causing the same symptoms.
 
My JD 50 started acting like your 620, and I noticed a puff of black smoke from the exhaust when it would recover. That told me that it wasn't starving for fuel and I discovered that it was a bad condenser that was making it act funny.
 
You're right on the condenser. They will fool you into thinking it is fuel when they go bad.
 
In addition to all of the below issues I also had one of the automatic shut offs have the small rubber washer that goes on the plunger that drops down had stuck to the upper housing instead of riding down with the stem. Easy enough to visually check on.
 

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