6620 Combine Fuel issue

It acts like it is running out of fuel. Have done fuel and air filters, cleaned sediment bowl screens at the bottom of tank and on injection pump. Removed hand pump and companion plug to check lift pump poppets and springs...OK. Electric pump appears to be working. Next step is to confirm supply by teeing into the pump line to see if it will maintain 20-25 psi.

Question, what regulates rack pressure in the pump? Is there a regulator fitting in the banjo bolt prior to leak off pipe?

Same engine as a 4440 if that helps.
 
I have had them clog up in yhe fitting coming out of the tank, have a 1/4" pipe plug ready and pull the fitting take it apart,,look for corn silk in the valve part.
 
I checked the stream of fuel out of the tank when I had the sediment bowl off. It was a good amount.

Don't see signs of air bubbles in the fuel filters when running.
 

Mine acted like that and I replaced practically everything between the fuel tank cap and the injector pump with no affect. It turned out to be the check valve on the side of the fuel filters.
 
When those 20 series were new, I worked for a dealer. Delivering a 8820 one day it stopped on the road. I was 18' wide with duals. John Deere had a service recall on those combines for silicone floating in the tank and would plug the fuel elbow as Tim mentioned. A dirty job pulling that fuel outlet on the edge of the road and removing a hunk of silicone used as a sealer.
 
Back in the 80's we had a new 6620 Side Hill, my Dad was bad about leaving the fuel cap off after re-fueling, so we had a charge of corn silk in the tank,, I removed the tank and flushed but some was still in there we would carry a pipe plug in the ash tray to hold the fuel as we cleaned the tank valve. One morning about 3AM were were near done on a farm running on frozen ground (so it was cold as Christmas) and we started loosing RPM's,, we looked at each other and "knew" what was about to be needed done....Darn it..
 
Decided to reconfirm everything. This time, I pulled the pipe off of the bottom of the tank, not a full stream. You were correct, plugged. Thanks Tim S.
 
Some of them had a stand pipe screen that helped a lot, and I have also used them in tractors.
AH106982 Screen - SCREEN ASSY-STANDPIPE ADD 32.45 USD 32.45 US
 

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