B1750 injection pump rebuild

[Jackblackmamba]

I’m rebuilding the injection pump with an eBay kit and noticing my injection pump is a little different than anything I’m seeing online for the 1995 Kubota 3cyl diesel b1750 tractor motor. Putting it back together I see that the plunger is keyed to a rack and pinion style slide. I’m unsure as to which way the toothed key cylinder fits into the rack. Does anyone have info on this or a manual specific to this type of injection pump? Looks like the parts in the kit (springs and washers) are the same as original.
Diesel Kiki 8450028
Np-pfr3kd50/2npg
Asst no 104293-3011
Bosch
15531-51012

 

[Jackblackmamba]

Based on the 3rd slot that I opened carefully, the pin and toothed piece fit just barely off the x axis (when looking in) when the fuel slide is all the way to the left. The plunger pin that fits into the toothed piece has the notch on the right in this position, see pictures for details.

 

[Jackblackmamba]

I also found out that the upper plunger pin is slotted to the screws in the back plate. Does anyone have a part # or spare pin screw available? I broke through the metal in the bottom of the injection pump pin housing, going to attempt to not fix that and only use a new pin screw because 1000+$ seems like a lot to spend on a 30 year old tractor I got for 2500$
See attached picture

 

[Jackblackmamba]

For anyone who also needs this pin the part info is
Bosch zexel pfr bearing pin 140255-0000

Injectionpumps.uk.co had 4 in stock June 10 2025, I bought 2 so I have a spare, pm me if you’re US based and this might save your a$$. Not sure if I’ll get the notification till the next time something breaks but who knows, good luck

 

[hagrid]

That roller looked a little rough. Are the cam lobes OK?

 

[Jackblackmamba]

That roller looked a little rough. Are the cam lobes OK?

I’ve seen better, but I’ve seen worse. Any idea if the timing shims have to be super precise? I just put them back where I found them. Tractor has been hard starting since I got it but always eventually starts (like 45 seconds of running the starter and blowing smoke). Thats what prompted me to rebuild the pump.

 

[Russell King]

Are the glow plugs working correctly?

 

[North Idaho Wolfman]

There are timing marks on the geared barrels and the rack.
That pin part you broke was to set the timing curve, without a bench to test it there is no way to set the properly, your pretty much guessing you go it right.
And because you changed the springs the shims in the plungers are worthless as you don't know the exact length and compression strength of each spring is, and that is what is adjusted with the shims.
As for the shims under the pump, they never change no matter what you do to the injection pump, they set the timing.

In conclusion "rebuilding" the pump with those parts in that way did nothing to improve the pumps performance, in fact it's degraded it substantially.

 

[ruger1980]

The pin that was broken is to equalize fuel delivery between each pumping element. There should be shims in the followers that the plunger seats against to equalize timing between the pumping elements.

Basically this is a task that you need an injection pump test stand to complete.

The roller does not look horrible. As long as you cannot catch anything when running your fingernail across the roller it should be fine.

Oh one more thing please make sure the components are a lot cleaner than they are now before assembly.