Fuel System Problem John Deere 5720

[scottkerslake]

My JD 5720 has only done 2000 hours and it is suffering from a fuel issue that Im yet to get to the bottom of. I have replaced all the fuel lines on the suction side of the injector pump as well as both filters but I'm getting air in the system. After about 10 mins at 2100 RPM it starts " hunting " and blowing smoke at the same time the rpm drops down to 1100RPM or there abouts at full throttle . I stop the tractor bleed the system and air is present where could this be coming from?? Im thinking that the water separator filter housing my be defective or the small inline prime pump. Has anyone out there in tractor world had this problem? Have tried asking local JD service center but all there interested in is coming out to take a look themselves and charging a small fortune for the privilege to do so.
HELP!!!!

 

[terraformer]

I had a similar problem with my VW diesel car. I kept getting air in the line near the filter. even after changing the tubing. I found the problem was a hose clamp. I was using standard screw type clamps and they didn't grab evenly all the way around. I ended up wrapping the junction with thin wire about times and twisting it snug.

I used clear fuel line on the rebuild. It helped a lot in diagnosis.