John Deere 4720 running rough

[K5lwq]

Not familiar with the 4720 but I think it is starving for fuel.

A couple of thoughts.

1. Is the filling cap vented? Try running it with the cap loose to see if it improves.

2. Is there a screen inside the tank on the fuel line that could be clogged?

3. Could there be trash in the tank that is restricting the suction line?

 

[radios1]

replace any rubber fuel lines, they can get cracks or pinholes that you can't notice. lastly, your injection pump may need to be serviced..

 

[Crankygranke]

I have the same problem with my 4520 compact tractor. 2004. 1800 hours. I've done filters, air and fuel, cleaned tank and screen, fresh fuel, replaced fuel lines also the transfer or lift pump. I located a check valve in the return line and just got it. I will post if it fixes the problem.

 

[arlen4720]

I replaced the small pump and unfortunately no fix..It was 78* today...so fuel is not ice Ing

You mentioned the hand priming pump before, but did you replace the small lift pump that is mechanically driven from the side of the motor? It sounds like it is most definitely a fuel issue. Does the turbo seem to spool up normally under load?

 

[Crankygranke]

You mentioned the hand priming pump before, but did you replace the small lift pump that is mechanically driven from the side of the motor? It sounds like it is most definitely a fuel issue. Does the turbo seem to spool up normally under load?

Yes i did. It made no difference at all. Nothing I've done has made any difference. Hopefully i will be able to change the fuel check valve. I've been to 2 dealers and they haven't been able to help without me taking it to them.

 

[thepumpguysc]

Cranky>> the return check valve, was it on the top cover of the inj. pump.??
The problem "I'm" having helping is>> JD put several diff. inj. systems on the 4720 AND the 4520.!!
1 was a Stanadyne/RoosaMaster pump & the other is a PFR system where the pump sits in its own hole & is driven by a separate camshaft..
& they get diagnosed differently..
SO.. if the poster can ID the pumps on their machines.. I can probably answer the questions..

 

[kevin37b]

This man knows what he is talking about . Give him correct info . Do not rely on guesses , go with a man that knows his stuff .

 

[radios1]

did you pull the line off after the petcock and check for a good flow of fuel?.

 

[Crankygranke]

yes, it was fine

 

[Crankygranke]

I replaced the transfer pump on the side of the block, it runs off the camshaft. each injector has it's own pump that also runs off the cam it's under the valve cover