John Deere 6620 combine won't stay running

I am going to post here as the combine forum is probably slowing down some. I wanted to move my Deere 6620 to another farm so I could make repairs on the rear axle last week. It will start but only run for 3 or 4 minutes. Then you open the air bleeder bolt on the fuel filters and pump the plunger on the injection pump removing all of the air and filling the filters and it will start and run another 3 or 4 minutes. Did that process a couple of times and still get the same 3 or 4 minutes of run time before it starts missing, looses rpm and dies. Was running perfect when I quit using it in the field three four weeks ago. Fuel filters would have around 75 hours on them. Electric pump on tank has never caused problems and you can hear it work. Tried to run it last week on Saturday when it was 40 degrees, same problem. Engine compartment may not have warmed up to 40 degrees. Does have 10% biodiesel in the tank. Do I have some frozen water in the filters?? Would the filters plug in 75 hours?? If the filters were plugged or iced would doing the plunger on the injection pump actually solve plugged fuel filters?? I did drain the water trap on the fuel tank and only diesel came out. Screen in the sediment bulb on the tank is clean. I have full flow from the sediment bulb out the bottom of the tank. Do I have some chaff floating up and down in the fuel line from the tank?? Wanted to get it moved before winter really sets in. Any ideas?? Thanks.

Could be any of the reasons you listed. Start with fresh fuel filters. The tank pump may run (motor) but how good is the pump itself? If you suspect tank blockage then you may want to pull the bottom bowl out to see what runs out. Have a few 5 gallon buckets ready so you can drain for 5 minutes to simulate what you see in the field. You are just going to have to try a few things. Again, start with new filters. I had a batch of fuel come in one time that took three changes of filters to clear up the 4010 in freezing temps. Take a deep breath and resign yourself to the fact you may spend a couple hours hunting down the problem. Be thankful it will not be a several thousand dollar problem.

Check fuel line under right hand countershaft bearing. bearings can go bad and let the races run against each other letting the shaft rub a hole in the fuel line. I'm guessing an air leak but also wonder about the tank pump . Does this have a fuel pump under the Inj.pump ? some engines did have this .

Have you cleaned the screen in the sediment bowl recently? They can get clogged pretty easily sometimes. They usually need attention at least once a season, especially if they have sat for a long time. Mike

I would suggest disconnecting the fuel line at inlet to the filters and let the pump run for several minutes to verify that the pump does move fuel. I would also remove the sediment bowl complete from the bottom of the pump. To make this easier duct tape the hose from a shop vac onto the filler neck ABOVE the fuel level. With the vacuum running you can remove the bowl and not lose any fuel.I have seen the standpipes in those bowls get packed so badly that it required a small drill bit to clean them out.

I would check to see if your fuel tank cap is venting properly. Had a Massey Ferguson combine do that in the field. Opened the tank cap and air rushed in. Put a new cap on finished combining.

I did work with the combine some this afternoon. Pretty cold today so I will crank it tomorrow when it is subpose to be 35 degrees. I took the sediment bulb off of the inline injector pump and checked the screen. Looked good. While I had the bulb off I turned the switch on and the pump pushed a good amount of fuel out with the sediment bulb off. So, I think that end is OK. Bought new fuel filters today and put them on. Bled the air out with the bleeder screw and plunger. Checked with my fuel supplier and the last fuel I got had the winterizer products in it. So, tomorrow when it warms up some I will crank it up and see what happens. If I continue to have problems I will check for sustained flow from the fuel tank. Thanks for the ideas.

I had an old 4430 last week that would not run good, and would die when you went to Idle, the primer pump felt funky so I replaced that, just because it felt bad,,and then it ran good,,I'm thinking it was sucking a bit of air around it, and it was causing all the problem,,at lest on that one....just more to think about...

check if theres a screen in a bowl near where fuel goes in at,thats a problem on some tractors too