This is for the benefit of any you that may like wrenching on your Universal M25 (or other Kubota based engines). Also for my benefit, so that I'll have an accurate record of what I've done.
Because I couldn't find a cost effective way to POP test the injectors on my M-25, I simply replaced the fuel injectors with Kubota Fuel Injector OEM Number 15221-53000, 15271-53002, 19202-53020, 19202-53021, 70000-65208 from an on-line tractor parts company. The replacement injectors were under $50 each (including shipping) and were factory set to open at 2170 PSI. The on-line price for the Universal p/n 298788 runs between $250, and $400 - EACH!
Looking at the old injectors, they weren't too bad, so I'll keep them as spares. Here is a pic;
You can clearly see the pintle, the nozzle, and a little carbon...
Note that the new injectors shipped with the plastic caps shown here on both ends to keep them clean, and in spec. Make sure, when installing the injectors, to buy and install a new copper compression gasket (seen in the lower picture Kubota P/N 17011-53620) for each injector, and to torque the injector to 45 ft lbs. Before installing, I applied a little
molybdenum-disulfide grease to the threads of the injector, so that I would get an accurate torque reading, and so that I can get them out in the future.
Here is the engine with the new injectors installed, but not yet painted;
(Note the original Kubota-Blue, under the Universal-Gold on the injection pump
I did not like that the old high pressure injector fuel lines had rust starting under the clamp which holds the lines together, so I bought new high pressure
fuel lines... I was puzzled, however, that they were not in the same shape, or length, as the old ones. So, I went to Harbor-Freight and bought a tubing bender, just in case...
Here is a pic showing the new and old high pressure fuel injector lines side by side;
The lower ones are new (I had just painted them), and the upper ones are the old. Moving from left to right are the lines for injectors 1, 2, and 3 respectively.
It turns out that I could have saved the $3 at Harbor Freight for the tubing bender. The reason is that the shape of the injector lines has changed to allow more room on the stbd. side of the engine. Here is a pic with the injectors painted, and the new lines installed;
Compare the picture showing the old lines with the picture showing the new lines. Note the extra space between the air filter and the injection lines.
Because the clamp seems to primarily function as a moisture-catcher, I am leaving it off. I'll see over time if I need to replace it.
The take away for anyone reading this far, is; if you are planning to replace a high pressure fuel line on your M25, you will need to replace them all!
I hope this helps!