L39 Fuel Pump Turn Up. Zoom-zoom, sort of.

[mike69440]

Power Turn Up Videos, B2501 to L39, & RTV900​

My 2005 L39 TLB has always been in need of more power, especially as it is ballasted to weigh approx. 8,200lbs and in winter is used to plow snow.
I added more fuel, 1-1/4 turns out, but left timing stock. I plan to add EGT probe just upstream of muffler soon to verify not running much over 1,200 F. Any recommendations for brand?
As I do not do 3pt. work with the machine, and only run at full throttle for emergency power, I am not concerned that I will hurt the motor.
I may bump the injection timing a bit also but need the EGT probe installed first.
My up hill speed on my test grade is now 6.1 mph vs 5.2 to 5.3mph before. Figure I gained about 5hp. I definitely notice it has more torque at lower speed. That was my primary goal.
It will now run 14-15mph up a slight grade in 12th gear, roading well in 11th (10 to 11mph) or 12th speed. With prior stock fuel setting, I only could use 12th gear on dead flat road.
I tried 1-1/2 turns and saw a bit more power (6.3 up my grade) but noticed some light smoke, so I backed screw in a bit to less than 1-1/4 turns from stock.

Loader cylinders also have been replaced with 5mm larger than OEM at 60mm for the lift and 65mm for the curl (just 5mm smaller than an M62)
At +8,000lbs, increased lifting capacity, and slight power bump the machine is as strong as it needs to be for its weight. Runs great with about 2600 hrs.

Hear are some links of videos of what is involved.
B2501 and all 3 cylinder motors including(L39)

"Increasing the engine power of a Kubota L2501, Part1”

"Increasing the engine power of a Kubota L2501 / D1703-M-DI-E4B - Part 2"

Fuel Timing and Fuel Screw Rack.

For RTV900, see

 

[mike69440]

https://www.amazon.com/Exhaust-Meter-Display-Temperature-Sensor/dp/B0BZY9ZK8D/ref=sr_1_28?keywords=exhaust+gas+temperature+gauge+kit&qid=1687450937&sr=8-28

 

[mikester]

Increased lifting capacity by pumping more fuel? Maybe I'm missing something, did you put a 100 gallon tank on the BH bucket to add more counter ballast to keep the rear wheels on the ground?

 

[mike0000]

Thanks for posting this info mike69440.
I have a L3901 and a RTV900, the L3901 I’m happy with current power, and it’s still under warranty so not goin to mess with it for now. My RTV however is a 2005, It could use a bit more power for hills while pulling a trailer with firewood. I have even had to resort to using my winch to a tree to pull a steep hill with a heavy load in the past.
Mike

 

[mike69440]

Increased lifting capacity by pumping more fuel? Maybe I'm missing something, did you put a 100 gallon tank on the BH bucket to add more counter ballast to keep the rear wheels on the ground?

750 Lbs of wheel weights and upped Cylinder sizes by 5mm

 

[5030]

Interesting. Last spring when both my M9000's went in to have the overheads adjusted at the Kubota dealer I asked Dennis (he's the lead tech and a good friend of mine as well) if he would 'turn' them both up and he did but used the shop pto dyno to set them. Remember, mine are both turbocharged and charge air cooled engines. He turned them both up (I presume he shimmed the pumps), I didn't really ask but they are both now putting out at rated RPM, 89 horsepower at the PTO and he showed me the printout from the dyno. He did tell me that they were both outputting a bit over the factory rated output before he turned them up and I left that to his discretion because he deals only with Kubota tractors 99% of the time and he's a factory trained tech. I say he shimmed the pumps because the pumps on my M9's are exactly the same in appearance as the pump on my Cat 3406 minus 2 cylinders and that is how you turn up a Cat engine. Neither of mine ever smoke except under a real heavy load and up on the turbo chargers. They don't even smoke when cold starting them other than a small puff of blue smoke and that is it.

I am this spring, going to remove the engine driven fans and replace both with electric push-pull fans and that should also increase the power output but I don't really know how much parasitic loss the mechanical fans consume. I do know that with a car, the mechanical fan consumes around 10 horsepower (which is why most cars today have went to electric on demand cooling fans) so I'm anticipating an increase in engine power and probably a decrease in fuel consumption as well. I discussed with Dennis and he told me to go for it. I already have plenty of power to run all my hay tools as it is but the mechanical fan bothers me so I'm eliminating it and going with an electrical reversing fan so I can use it to blow the chaff out of the radiator and heat exchangers without having to resort to my hand held blower all the time. If it's good enough for John Deere, it's good enough for my Kubota's. At 4000+ and 6000+ hours on them they both run like sewing machines anyway.

 

[mike69440]

Crimped on cap with typically marked yellow dot must be pried off. This Voids Warrantee.

On non turbo Applications opening up screw 1/3 to 2/3 turn until you observe a bit of grey smoke under full load will net about a 10% power increase, depending on how detuned the engine was originally.

s you can adjust the Throttle linkage and stop screw to make sure you are getting full throttle. Don’t adjust so you are forcing stull or binding.

An EGT gage ins recommended to be installed with TC in the exhaust manifold. 900 F I good be scared of over 1100 F If you are pulling full throttle for more than 30-45 seconds at a time, i.e. 3Pt hitch PTO stuff, don’t Run full throttle without an EGT.

To get even a bit more power, you can change the shims between the roller tappets and plunger. Fuel Pump disassembly is required.

When shimming a diesel fuel pump, you typically decrease the shim thickness. This is because the shim is used to adjust the clearance between the pump's plunger and the fuel inlet valve. Decreasing the shim thickness increases the clearance, which can help to improve fuel flow and reduce pressure in the system.

Here's a general guideline:

If the pump is not delivering enough fuel, you may need to decrease the shim thickness to increase the clearance.

If the pump is delivering too much fuel, you may need to increase the shim thickness to decrease the clearance.

However, it's essential to consult the pump's manufacturer instructions and/or a repair manual for specific guidance on shimming the diesel fuel pump, as the correct shim thickness may vary depending on the pump model and application.

Some experts have played with fuel pump timing. I suggest not to go there. On the few setups I have seen; in order to change timing means you change gear tooth alignment. Seems dangerous.