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John deere 4039d engine issue

pajibson

Senior Member
Joined
May 29, 2013
Messages
312
Location
metro detroit
This engine is in a square shooter SS636. Put a genuine john deere reman engine in with new injectors and i get zero throttle response. But if you grab the joystick & put a load on the engine the injection pump will rev it up to keep the idle rpm.
Pinned the engine @ tdc and verified pump timing. Installed new lift pump. Had the injection pump rebuilt at a reputable shop and same problem. I have 3.5psi coming out of the lift pump. Took the pump & injectors back out and took them back to pump shop. I watched them run it through the test procedures on bosch test machine.
So at this point I'm wondering what else could be causing this. Anybody have any ideas?
 

MarshallPowerGen

Senior Member
Joined
Nov 26, 2017
Messages
442
Location
Northwestern USA
Occupation
Generator Technician & Equipment Mechanic
So if you move the throttle linkage at the engine, you get no response?

Air/fuel filters new? Any smoke? Have you monitored for any drop in lift pump fuel pressure with engine loaded?
 

pajibson

Senior Member
Joined
May 29, 2013
Messages
312
Location
metro detroit
Correct. Move the throttle linkage and get no response at all from the engine.
All new filters. I did not look @ lift pump pressure when i tried loading the engine. There was some smoke but i was running this @ night under LED work lights so i couldnt really tell you color or volume well enough to speak to it.
Fuel shop told me to try running off a separate supply and route the return into a separate container too. They were thinking maybe a volume problem or restricted return.
 

tractormech

Senior Member
Joined
Feb 19, 2015
Messages
347
Location
florida
Go to the right rear of the fuel tank and pull the fuel line off and it should have good fuel flow. If not unscrew the big hex nut fitting out-there's a screen on it and it can get stopped completely up. Have some buckets to catch fuel because it will really come out of the tank-it's like a ! inch pipe fitting going into the tank. If that isn't the issue and the fuel filter is the type that has the plastic nut that threads onto the filter base check it. I had one develop a small hairline crack that would suck air. I'll bet the screen is stopped up though.
 

Delmer

Senior Member
Joined
Jan 3, 2013
Messages
8,863
Location
WI
Or an injection pump model, even picture. And what happened to the old engine?
 

pajibson

Senior Member
Joined
May 29, 2013
Messages
312
Location
metro detroit
Sorry, I clearly forgot some details I did mean to include. thats what I get for trying to hurry old engine serial # is T04039D474697 new # is SE4039D792263. Pump is a stanadyne DB2 #2435-4972.
Old engine had ridiculous amounts of blow-by and was just slobbering out the draft tube. would barely run.
Vetech I think you're absolutely right something is getting missed. I just cant figure out what. I don't think the engine is already running at full fuel (load) because when I grab the joystick and give it a little bit of a load it does respond. just not with the throttle.
tractormech thanks for the tip on the pick up screen. I will check that too.
I appreciate all the help guys and I will follow up once I get this back together and retest. If anybody comes up with anything else I am open to more suggestions.
 

mg2361

Senior Member
Joined
Jul 5, 2016
Messages
5,055
Location
Pennsylvania
Occupation
Equipment Mechanic
A check of the fuel supply pump pressure would be in order. I'll bet you will see a vacuum.
 

Txhayseed

Senior Member
Joined
Dec 23, 2019
Messages
610
Location
Texas
Are you sure you dont have a load on the unit when your starting and running and once you stroke a control you change the swash plate and that allows your engine to rev up since you dont have a parasitic load of a hydraulic pump ?
 

pajibson

Senior Member
Joined
May 29, 2013
Messages
312
Location
metro detroit
okay here is the follow up. got the pump and injectors reinstalled. We ran it from a separate fuel supply and the return into a separate jug, No change. had plenty of fuel returning from the injection pump into the jug. had black smoke from the exhaust like it was under a load. I guess our next step is going to be to pull the coupler shaft to the hydraulic pump and try again. I'll follow up again later. Thanks again folks
 

bunkclimber

Well-Known Member
Joined
Jul 29, 2009
Messages
116
Location
MD
check the shutdown linkage lever on the inj.pump,its the linkage arm on the side of the pump opposite the throttle control lever..sometimes the lever isnt in the full fuel clockwise position and will limit the amount of fuel delivered to the engine regardless of the throttle lever..it'l fool ya into thinking the pump is bad or not adjusted right. I've had a few gensets that use the Stanydyne DB pumps do that to me..wouldnt rev past 1200rpm
 
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