Power loss and will not rev up

GFL

New User
I bought a 4020 at an auction last year and have pretty much regretted it ever since but now I do not have the money to replace
it. Anway, when I bought it the RPMs would fluctuate wildly. The tractor had sat for a while so I was not terribly concerned.
After a while it seemed to ease up and run somewhat better but not right. Recently though its power has dwindled down to practically nothing and the throttle lever has virtually no response other than to turn the tractor off. I have changed the fuel filters. I blew the line back into the tank. Still no power. I do not have any test equipment. Is there anything that I can
check to figure out what the issue is? Thank you.
 
Ooh yes it's time for the pump to come off,,but for now try removing the return check valve in the return fitting on the injector pump,,it sounds like it is clogging up,,this may buy you some time, but is not a permeate fix..
 
Check the fuel shutoff under the tank.
Normally a clogged check valve in the inj
pump return el will cause the tractor to die
almost immediately after startup.
Retainer ring particles could be sticking the
metering valve. Still calls for inj pump removal.
 
I'll bet injection pump too. Confirm by seeing how the engine runs with the two screw timing cover loose on the pump side. If it responds better with the fuel leak, pump needs repair soon. Wait too long, and the retainer pins will shear off, possibly making repair cost MUCH worse than what it would be now..
 
I had my JD 3020 pump rebuilt by one of those high shops but it never revs up as it should since, I took off the return line and made sure it was clear and open which it was but still stop rev up like it should. I also installed new injectors but disappointed it gets up to about 1700 rpm and struggles to get above that even just setting still.
 
If it won't get to 2500 RPM there's still something wrong. See if it will run OK with the pump timing cover loose, if it's better with the fuel leak either pump return fitting needs cleaned or replaced, or there's still a restriction in the injector leakoff line back to the tank. This is assuming the supply side through the filters to the injection pump is OK. May also need to make sure the air intake system has no restrictions also, test run with the air intake disconnected at the manifold. I've seen engines that would not quite get up to speed due to lack of needed air at high speed.
 
Check the delivery pump on the right front section of the engine. Looks like a gasoline fuel pump. One sign of delivery pump failure is diesel fuel in the crank case.
 

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