648 G2 engine flutter

[Log-it-up]

Good afternoon everyone 
I've got a 648G2 that has flutter issue, when it runs good it's awesome but it's seems like it starved for fuel every now and then (mainly when at the furthest point out with a hitch on) I've drained and changed the fuel filters put all new seals and o-rings in the water separator 
When it's working correctly it's got all kinds of power but then starts to loose power and flutter enough where you can feel it in the motor, most of the time I can push in the clutch and save it from shutting off letting it idle for a few seconds and be on my way, some times it will go a hole turn without doing it some times several times per hitch 
Any help would be appreciated thank you 

[barbender]

Check your fuel lines. I've never ran John Deere forestry equipment, but in other machines I've had the fuel lines delaminate internally and restrict the fuel intermittently. The symptoms are exactly as you describe. Is there a primer bulb on your system? A quick way to check for a restriction is to check that. If you push it and it primes up, getting firm, that's good. If it doesn't come back up on its own it indicates an upstream restriction. 

I've also had machines that had a fuel shut off solenoid on the tank, so it would cut off the fuel when you turned off the master switch. They are for the fire suppression systems. Anyways, I've had those get weak or fail outright and shut the fuel off as well. 

[BargeMonkey]

You've got something in the tank periodically blocking the tank, your lift pump is worn or you've got a cracked filter housing / bad fitting. My money is on a filter housing. I changed out a pricy injector pump in the tundra because of a similar issue doing basically the same thing, did the same thing with a new pump, couple barb fittings and some hose ruled out my problem, water filter assembly was cracked and sucking air. 

[Log-it-up]

Thank you guys I'll have to check into those things might be a couple days where in a bit of a cold snap

[teakwood]

Same as Barge and Barbender, blow back fuel line. my old 540A has a 90degree fueltank fitting which starts to reduce it's flow capacity over time. maybe tankscreen is getting clogged 

[Log-it-up]

I checked fuel lines front to back put a wrench on all fittings to check for tightness, changed filters double checking and making sure they are tight, the fuel tank is about half full so I was sorta able to see the bottom looks clear but I'm going to run it lower so I can get a good look, but ran fine all afternoon 
   It's on site so I don't have access to air compressor, but if it continues it's my next step to get one and blow back through them 
 Not really a big fan of the quarter turn JD filters with the locking ring but it what is for now just trying make it through the next few weeks mills/transfer yards are getting full here 
Thanks for the advice from everyone 

[Log-it-up]

Just a update
I ran the tank just about dry so I could see the bottom, nothing floating around in there and to my surprise it looked really clean 
Added some c-foam along with fuel treat ment no problems the last few days 
 I did notice there is ball connected to a cable dose any know if this to drain the water off the bottom of the tank I know my 440C has one of these but I had removed the tank when I found it and glad I never pulled it because it would have never shut right with all the stuff and things that had collected over the years 

[BargeMonkey]

My money isn't on the tank but it's possible, my 450C had wood chips in the tank and coughed till we cleaned the tank. After I got bit with changing that pump and finding a cracked housing that's the first place I go anymore on a deere for fuel trouble.
 

[Log-it-up]

Barge-
Was there any sign on the exterior of the filter housing that you could tell if it was cracked or how did you find this out just so I know what to look for

[BargeMonkey]

No, small hairline crack in the housing where one of the fittings threaded in. I've seen the plugs go bad, the rings get old and brittle, break. Does the lift pump feel right ? Diaphragm goes bad, that's easy to check. I don't know on a G2 but on my G3 there's just enough wiring maybe youve got a loose wire ? But typical it would shut right off from the pin and not cough. 

[kiko]

You said you check all the fuel lines for tightness.   All the metal supply lines on the suction side have grommets in them that deteriorate.   From the first fuel filter all the way to the injection pump inlet.