John deere 950 rough idle.

thepumpguysc · Oct 19, 2018

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 · Oct 19, 2018

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

njb347 · Oct 19, 2018

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 · Oct 19, 2018

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 · Oct 19, 2018

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 · Oct 19, 2018

Here is the timing procedure.

thepumpguysc · Oct 20, 2018

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}