John deere 950 rough idle.

[njb347]

I have a john deere 950 and recently had problems with them fuel injection pump and a high pressure fuel line. I bought all three new high pressure hoses and paid 1k to have my fuel injection pump rebuilt. I returned home and put everything together and now my tractor runs but it doesnt get rpms like it used too and if I idle it down some it will idle down and die. I am completely honest and dont know a ton about diesels but I enjoy learning.

Could one of my injectors be clogged? Could I remove the injectors and clean them and replace them (Dont wanna spend another 1k on getting injectors rebuilt)? Was I supposed to adjust some kind of timing on the fuel pump that controls the idle ( the fuel squirted out of the fuel injection hoses in sequence when I'd turn the key)?

Thanks I'm advance for any tips or help. Hoping I get this thing running.

 

[super55]

Did you by chance bleed the injector lines. Really sounds like you have some air still trapped in the fuel lines. Key point to remember is that air is compressible fluid is not. I don't know if the 950 has a primer bulb but if it does you might want to crack the lines at the injectors and prime until you get a steady flow of diesel coming out of it.

Just out of curiosity what was going on that led you to rebuild the pump and replace the hight pressure line?

 

[thepumpguysc]

The ONLY thing that "wears out" an injection pump is poor fuel.. either the quality of the fuel{water} or poor filter maintenance.{dirt}
Did u refill your tank w/ diesel fuel or Bio-fuel??
Did u CHANGE the fuel filter or just blow it off?
Did u replace the washers on the inlet line to the pump or just reuse the old ones?
What about the return lines?? new gaskets??
If its all new, {pump & injectors}, its likely THOSE aren't your problem..
Those mdl. JD's{Yanmar} have a very poor filter system..
The timing is done by steel shims under the injection pump.. You did put them back on the new pump didn't you?
NO, you cant clean the injectors.. unless u take them apart.. & that's not advised..

 

[TimberHole]

Who installed the pump? I have got away with reusing the same quantity/thickness of shims when reinstalling the same pump on the same 950 block but the correct way to do it would be to follow the timing procedure. I believe that involves disassembly of the number one plunger on the pump but I never did it.

 

[thepumpguysc]

Your right TimberHole.. 99.9% of the time, the old shims are reused w/ no problems. Bolt'r down & off u go..
The shutting off at low idle is suspect tho.. that sounds like air in the system or poor fuel quality or supply pressure??

 

[TimberHole]

Could definitely be something as simple as bad fuel. I can’t help but wonder how the current symptoms compare to the symptoms that led to the replacement of the high pressure lines and the rebuilding of the pump. The high pressure lines are very simple, they’re either good or they’re not. I’ve only worked on a couple of these but I think many of these have bad washers between the injectors and the burn chambers. If those washers are bad you’re losing compression. When I’ve pulled the injectors the holes in the head are so polluted it takes about 45 minutes per hole to clean them. It would help to know the problem that started all this. I hope the OP doesn’t post this issue and then fail to return to the thread, as often seems to happen.

 

[njb347]

I know this is alot but I'll try to start from where my problems began. I got this tractor from my grandma and the tractor was just left out side even though it was in running condition when I got it I went about changing oil flushing radiator hydraulic fluid and all filters.

One day the fuel hose that goes from the fuel filter to the fuel pump started having a pretty good leak and I went to john deere and got a new 2 ft piece of hose to replace it. Apparently the old hose wasn't being made anymore as you can tell it isn't same size outside diameter because my spring clamps wouldnt work around the hose. I called john deere and went AND exchanged that piece for another piece that looked just like that one they had gave me and they swore up and down it would work. Finally after getting it back together I tried bleeding my lines and the bleed screw so that i could fire it up but the high pressure fuel line closest to the front of the tractor wasn't squirting it would just drain diesel while the back to squirted diesel like normal. I ordered all three new high pressure fuel lines in case of something in my fuel and had read on here where plungers get stuck in the fuel pump if there's a little water sitting on the plungers it may rust them. So I banged around to try and unstick the plunger and finally went to taylor diesel in little rock and got my pump rebuilt brought it home and the tractor fired up (I did buy new shims to go around the fuel pump because the old ones were worn) but it has been surging and loping since I got this done and I'm scared it may be a injector after spending 1k on that fuel pump it makes me sick to spend more.

So here's what I've considered I may have:

My fuel hoses need clamps because its sucking air.

I haven't timed it right with those shims.

This is my first time working on a diesel and I really wanna use this tractor and dont wanna give up on it and I love tinkering on it but man this thing has been a headache lately.



Sorry i haven't responded in a while we were called out to help with hurricane michael clean up and I just got home a couple days ago. I really do appreciate any help from you guys.

 

[njb347]

I dont understand how these shims work and maybe that's my problem. When I got home I just put the pump back on the tractor with the two shims John deere sold me behind the pump and fired it up. How does this work?

 

[thepumpguysc]

AHHH.. Now for the rest of the story..Lol
The shims are set from the factory to adjust the timing of injection..
They are VERY specific to your engine.. Your neighbor might have a 950 & the shimming would be/could be different.
You have to keep the right AMOUNT/THICKNESS of shims for YOUR engine..
Unless the shims were measured at JD & the same amount/thickness were handed back.. THATS a problem..
BTW> the shims don't wear out..

 

[njb347]

AMD the shims are the copper color things I put between the tractor and pump right?

What would I need to do to get it back right now that I have messed up and thrown the old ones away?

 

[thepumpguysc]

I'm working on a 650 RIGHT NOW.. or should I say, its waiting for pick-up..{done}
It came to me not running.. The control rack was rusted in the shut-off position..
I rebuilt the pump, put it back on & it ran smooth for a few minutes & started to run bad..
I loosened the lines AT THE INJECTOR & found cyl. #2 didn't make any difference in the engine noise when I broke the line loose.
I KNEW it wasn't the pump because I JUST rebuilt it.. it HAS TO BE the injector..
Ordered the injector & tool from Hoye.. installed.. problem solved..
JUST BECAUSE u had the pump done, doesn't mean everything is good.. You only did half the job..
Its kinda like taking a bath & then putting on dirty sox..

 

[thepumpguysc]

Yes, the copper things are the shims..
Buy a book or get someone to explain the timing procedure to you..
Its lengthy & involved..

 

[njb347]

Okay I'll try to look something up. Do you think I could've messed up the tractor running it since I've had it back I mowed the yard twice on like an acre?

 

[TimberHole]

This is starting to make more sense. The shim kit I bought from Deere included 4 shims. Two were .010 and two .015. This allows every combination of shim from .010 to .050 (except .045 now that I think about it). When I removed my pump I could not remove the old shims without damage but I did keep them. The factory shim stack included two .015 shims for a total thickness of .030. Did you keep your old shims???

If you installed all the shims included in the kit you have .050 of shims installed. Likely way too much.

Think about it this way. The pump is mechanical and begins moving fuel when the plunger is displaced a very specific distance. The plunger is driven by a cam lobe so the greater the distance from the pump to the cam the later the fuel begins to flow. If I am thinking correctly, too much shim will result in late fuel delivery or retarded timing. Pump guy knows about 1,000 times more than I about this stuff so he can correct me if I am thinking wrong.

Here is a pic of my two original .015 shims and the two leftover .010 shims from the new kit.

 

[TimberHole]

One more thought. If I recall correctly the timing procedure requires the disassembly of the number one plunger and installing a test pipe. Because of this disassembly I believe the book calls for the replacement of a couple of seals during reassembly. I couldn’t find the seals but they are available somewhere because the pumps are rebuildable.

You could make the test pipe from one of your old lines. I bought some lines from the salvage yard for this purpose but never went thru the timing process so never made the test pupe.

It might be easier for a weekend Warrior (I’m including myself here) to install with .030 and use trial and error from there. You might pull the pump 3 to 5 times but you wouldn’t need to disassemble it. I bet it would run decent with .030 but just guessing.

 

[TimberHole]

Here is the timing procedure.

 

[thepumpguysc]

NJ> they should NEVER sold u those shims w/o asking some questions.. They are not your friends..
I would find someone/a dealer that has more insightful people.
If they just sold u a "pack" of shims & u installed all of them?? Timber is right, its to much..
U need a "caliper" or 0-1 micrometer to measure the shims.. unless they're stamped w/ their dimensions.. which I don't think they are.
Seeing u prob. don't have those tools but are familiar w/ removing & installing the pump.. DO as timber suggested, remove a shim..
1 of the thicker shims will prob. get u where u need to be.??
.. does it start real hard??
& u paid HOW MUCH for a rebuild?? 1000.00??!!!!! HOLY SH**!!!

BTW> U need to have clamps on all your fuel lines.. {rubber}

 

[Rock knocker]

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