Hey all. Long time lurker but first time posting. Had a few questions for you all.
I have what I thought was a failing injection pump(JDB) on my 4020 but wanted to get your 2nd opinion. For quite some time I've noticed when the tractors running the rpm will creep up on it's own unless I jockey the throttle lever, then will stay pretty constant after that.(For a while) Also at first start it will run up a bit unless I catch it with the hand throttle. For the most part it still runs pretty well until just a few days ago when I was clearing snow in my driveway. It seemed to lose power and was missing, blowing white/ grey smoke out the exhaust with what looks like raw fuel collecting on the pipe flapper. It does seems to clear out a bit if you bring it back to idle but skips again when trying to hold higher rpm.
I limped it into my shop and was dead set on removing the injection pump and while inside I got to checking some other things and noticed the oil is very runny and over full.
I've read most times that's caused by the transfer pump, or the umbrella seal on the pump driveshaft. With all that said would a failing transfer pump cause any of the above symptoms?
I pulled the inspection cover on the injection pump expecting to see flex ring bits but it was clean. That makes me wonder if the transfer pump is causing my issue if it can't supply enough fuel to the injection pump?

Got the pump put back together last night and finished reinstalling it this evening with a fresh oil change. Took a bit to prime but it came to life and purrs like a kitten. Sad thing is its never sounded this good or ran this clean in the 5 years I've owned it. I thought that's just how it was not knowing much about these older diesel's. Poor thing probably needed a tune up the whole time.

The pump went together very smooth and relatively no issues other than the weight basket getting upset the first time trying to get the throttle linkage in. Couldn't get the linkage to slide in below the little spacer that sits inside the weight basket. Had to pull it out and redo it. Went together fine after that.

Overall very rewarding and glad I tackled it myself. Its been a while since I actually wrenched on something. Anymore these days we just replace major components to "fix" problems. Felt good to tear that pump all the way down and hear that engine come back to life!

Thanks for all the help!

A few more pics of the pilot tube

Well I got it all apart tonight and sure enough the flex ring was to blame. That timing advance screw was making me very nervous. I gave it a few big whacks with a punch before I tried anything, also thru some heat at it. I had to grind down the sides of a T45 bit just a hair and used my impact screwdriver first. That didn't touch it. Hit it both loosen and tighten directions to try and jar it lose but ended up putting my impact gun on it set to the lowest setting. Spun right out. What a relief!

The pilot tube was in better shape then I thought it would be. I have one on order since I assumed it would be scored but there's only one tiny line in it that I think I can smooth out with some emery cloth but figured I'd get your guys opinion on it.

Here's some more pics. Overall successful night.

Looks like there's some NASTY deposits and/or "slime" from fuel that went bad on the interior of the I.P.

Pulled the injection pump off and opened up the rear cover. Not surprisingly I found little bits inside that has to be from the gov ring.

Stay tuned.

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Thanks. Hard to say what the smell is like. Defintetly doesn't have strictly an oil smell. A bit exhaust/sooty smell as well as im sure there's some blowby fumes that make their way into the crankcase.

Well you could try a new lift pump they are only about 60 dollars if it doesnt fix if youll have a spare but that still doesnt Address your throttle issues

Took the lift pump off tonight. Hard telling but the inside bottom of the pump looks a little washed?

Also grabbed a pic of the timing marks on the pump at tdc, the rotor mark looks a bit off from the one on the pump housing. Is it ok to take off as it is or should I line the two up when I remove it even though it'll be a bit past tdc?

The base of the injection pump was pretty wet so wondering if it's the umbrella seal that's compromised by the flex ring.

Set the flywheel mark on tdc then it wont matter if the pump is off just a bit just line it up when you put it back on . Lift pump looks shiny what does it smell like ?

I'll start with the lift pump but have a sneaking suspicion both pumps may need addressed.

If injection pump is the DB or JDB model and engine speed ever changes on it's own for no reason there's a good chance the governor weight retainer ring is failing inside, and pump will need repair soon. When it fails fuel inside pump will also find it's way past the shaft seals too. Run it long enough, and the retainer pins WILL shear off, causing a complete loss of governor control. I just finished calibration on a JD 4000 pump in for repair for the same trouble.

I would get a new lift pump its easy and the cheapest to replace then you might have to send the injection pump off . When you pull the lift see if the backside where the lever is Id shiny from fuel