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Learning the HARD way...
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Discussion Starter · #1 ·
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!:eek:

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:rolleyes:)

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!
 

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Hi,

Thanks for a great post. I replaced the injectors on my 5416, but paid a bit more for mine than you - ah well, support your local Kubota dealer :)

I noticed the air filter in your photos. Where did you get this? Do you have a part number? I have found that a lot of the "engine" noise when running is actually some kind of pulsing or resonance in the metal intake "trumpet" that is standard on the 54xx engines. Did you add the air filter, and if so did you notice a change in the noise levels? Also, did you notice any change in engine performance?

Thanks Again
 

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Learning the HARD way...
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Discussion Starter · #3 ·
Hi,

Thanks for a great post. I replaced the injectors on my 5416, but paid a bit more for mine than you - ah well, support your local Kubota dealer :)

I noticed the air filter in your photos. Where did you get this? Do you have a part number? I have found that a lot of the "engine" noise when running is actually some kind of pulsing or resonance in the metal intake "trumpet" that is standard on the 54xx engines. Did you add the air filter, and if so did you notice a change in the noise levels? Also, did you notice any change in engine performance?

Thanks Again
The filter pictured is a K & N RU-2450 Universal Air Filter. You can find it here;

It is not a perfect fit, but close enough, and better than the stock air filter.

I have not noticed a change in performance, but it is less noisy (it doesn't rattle).
 
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Learning the HARD way...
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Discussion Starter · #5 ·
Thanks!...

One thing: I am not sure if the fuel return rings ("Eye-Joint" a.k.a. the thing that connects the little rubber fuel return hoses) are included with the Universal badged injectors - I did see a picture that implied this. The Kubota part number is 15221-95690. The rubber hose's Kubota part number is 15261-42500.

I just ordered 3 of them because the number 2 cylinder seems to be leaking fuel from this joint. They are under $7 each.
 

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Thanks so much for responding to my question about the air filter and the noise level of the old one vs the K&N. It's nice to know that it was not just my imagination that a lot of noise is coming from the air intake. I'll be ordering one of the K&N filters right away.
 

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Quick question - do you have part numbers for those high pressure fuel lines? I have a similar problem RE: rust under the bracing...

This is awesome! Thanks for sharing...
 

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Discussion Starter · #8 ·
Kubota part #s; 15261-53710, 15261-53720 & 15261-53730
 

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HELP!

So, I had the same problem as you regarding the high pressure lines. I changed them out and when I did, I installed the Kubota 70000-65208. I replaced the copper seals as well, and the motor fired right up! However, I now have a big problem...

When the motor is not in gear, I can rev the motor to 2500 or 2600 RPMs and it does great. However, when I put it in gear, it struggles. I can only get it to go to 1200rpm in Reverse and 1500rpm in Forward.

I thought it was a bad injector, but I had them tested and they're great. I thought it was fuel, so I removed all old fuel and replaced it and still the same problem. The fuel filters on the motor are both new, the oil is new, the coolant is new and full... The fuel lines are all tight - what am I missing?

Any help is greatly appreciated.
 

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HELP!

So, I had the same problem as you regarding the high pressure lines. I changed them out and when I did, I installed the Kubota 70000-65208. I replaced the copper seals as well, and the motor fired right up! However, I now have a big problem...

When the motor is not in gear, I can rev the motor to 2500 or 2600 RPMs and it does great. However, when I put it in gear, it struggles. I can only get it to go to 1200rpm in Reverse and 1500rpm in Forward.

I thought it was a bad injector, but I had them tested and they're great. I thought it was fuel, so I removed all old fuel and replaced it and still the same problem. The fuel filters on the motor are both new, the oil is new, the coolant is new and full... The fuel lines are all tight - what am I missing?

Any help is greatly appreciated.
Does anyone have the original specs to the factory installed fuel injectors? Making matters worse, I no longer have the original injectors...
 

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Discussion Starter · #11 ·
The M25 should rev to 3000 RPM, so you have a problem there.


The injection pressure should be 1991-2133 PSI. The opening pressure of 2070 psi was stamped on my new injectors.

How is your transmission? Have you ever changed the ATF?
 

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The aft most injector on my M25 always looks wet around the engine, I've tried tightening it as much as I dare. Would replacing the copper gasket be a reasonable first step? Would you suggest replacing all 3? Otherwise there the fuel system is fine.
 

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Discussion Starter · #13 ·
The aft most injector on my M25 always looks wet around the engine, I've tried tightening it as much as I dare. Would replacing the copper gasket be a reasonable first step? Would you suggest replacing all 3? Otherwise there the fuel system is fine.
That was the problem that led to my purchasing a new set of injectors. I tried replacing the copper gasket, the aluminum gasket and the "Y" fitting on for the return line. The fix was to replace the injectors. Some day I hope to get my hands on a pop-tester so that I can rebuild the old ones.
 

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Learning the HARD way...
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Discussion Starter · #15 ·
Sounds like either your transmission or packing gland are giving you unusual amount of resistance. Is there good fluid in trainy?
If this post was directed at me, my boat has a PSS dripless shaft seal, and the prop shaft spins freely when it should.

If it was directed at bomberhart, he posted his problem 6 months ago. I hope he has resolved it since then.

Realize that these engines are going on 30+ years of service.
 
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