L2600DT - RPM Surge and Lag Issue

[BrianNH]

Hello!
Prior to purchasing my tractor this spring, I've been reading a lot of the great information on the forum. I'm going to get to the point, so you don't have to read a long paragraph. Thanks in advance.

Tractor in question: 2001 L2600DT with 376 hours.

Question: Is this tractor SO sensitive to moisture that, when PARKED outside in a misty, soft rain the moisture will create "water in fuel" symptoms?

History: Recently purchased from farmer neighbor in great condition. Always parked in doors. Drove tractor home 2 miles in a strong rain. Ran great the whole way. Had about a 1/4 tank of diesel. Farmer was using the tractor daily.

Issue: I parked the tractor outside. It rained. Some days later when I went to use it, the RPMs would drop to almost stalling when attempting to drive in 2High or RevHigh, or use the FEL then surged/dropped continually. Even at a standstill under no load the RPMs surged/dropped.

Parts replaced: Using Kubota brand parts, I replaced air filter and fuel filter. Added 5 gallons of fresh diesel. Bled the fuel lines at the filter and injection pump. Fired up the tractor. It ran great for three hours of work. Parked it for the afternoon...

Continuing issue: ...same day five hours later it started to mist out preceding an oncoming rain. Started it up, attempted to drive to the barn and the darn RPM issue was anew! RPMs surge/dropped even with new filters and fuel!

What the heck?
Thanks,
Brian

 

[North Idaho Wolfman]

Question: Is this tractor SO sensitive to moisture that, when PARKED outside in a misty, soft rain the moisture will create "water in fuel" symptoms?

NO, well not unless your running it with a cracked or removed fuel tank cap.

Sounds like you have water and or algae in the tank.

Drain all the fuel out of the tank, look at that fuel for black slime and or water.

Refuel it and add biocide treatment.

Keeping the tank full will slow condensation in the tank, same goes for storage tanks.
if your keeping fuel stored treat that fuel with a biocide too.

 

[BrianNH]

Thank you Wolfman. I'll drain the tank, inspect the fuel and add a biocide. I don't store fuel, rather, I get it on an as needed basis. Cheers! Brian

 

[BrianNH]

Wolfan,
With regard to my L2600DT RPM surging and dropping, I confirmed the following:
1. Good diesel flow to the filter and injector pump.
2. System is well bled.
3. Removed the fuel injector needle valve (used to bleed the injector pump) and flanged
bolt/shaft (fuel line connection) to the injector pump. This tractor does not have a
screen before the injector pump.
4. Removed the fuel tank, flushed out with diesel. Small particles of what looks like "algae"
came out along with a golf ball sized glob of black goo the consistency of putty.
5. Assembled the equipment, bled the system and the tractor started up well and ran
great! I parked the tractor for about week in my cool, dry garage.
6. When I went to start the tractor again, it would not start.
7. I opened the bleed valve. No air at the filter. Opened the needle valve for 30 seconds.
Closed the valve.
8. The tractor started after some turns of the starter. However, when I put the tractor in
gear (high 2 or high reverse) to confirm it was running well, the RPMs dropped to 1K,
the engine stalling if I didn't engage the clutch.
9. The farmer I bought the tractor from came over. We did all the same stuff again;
removed the filter, checked for fuel to the pump, took apart the needle valve and fuel
line shaft to the pump, futz'ed around with the throttle linkage, etc..
10. The tractor worked well again and was able to move dirt and such. Shut it down.
Started it up. Again, engine lacked power.
11. His diesel mechanic friend recommends "pop testing" the
injectors. Not sure what that is.
12. If those are fine, then next go to the injector pump to.....not sure what the
troubleshooting is for that.

The farmer owned the tractor for 5 months and said it worked fine for him always. I've just worked on this tractor!

Thoughts?

Thanks, Brian

 

[rjcorazza]

Fuel issues can be aggravating. From a logical perspective, if you got globs of algae out of the tank upon cleaning, and redeveloped running problems, likely the fuel system is still contaminated and moving through.


Sent from my iPad using Tapatalk Pro

 

[North Idaho Wolfman]

I sent you the WSM via Email.

It is either getting air in it via a bad filter housing seal, line, bad connection, bad lift pump, or more than likely algae in the tank or along the system.

The screen I was talking about is a screen in the inlet of some of the filter housings.

You need to start at the tank again and run through all the fuel lines and verify good clean flow.

When you replaced the fuel filter do you do O-rings too?

DO NOT mess with the injection pump, it's way beyond what you want or need to get into yet.

 

[BrianNH]

Hi wolfman,
Thank you for the WSM link.
The tractor has a strong flow to the IP.
When I replaced fuel filter, there was not an O-ring to replace.
Nor does the Illustrated Parts Manual list a fuel filter O-ring.
The aforementioned Manual does list an O-Ring for the Filter Breather Plug. I do not recall seeing this when I adjust the Plug to bleed the line....

It is odd the farmer owner I bought the tractor from had zero issues and all I have is an issue! He has taken my calls, came over for 2 hours to help and is going to truck the tractor to a diesel mechanic friend (we will see). So I believe he is honest.

Jeepers this tractor!
Thanks, Brian

 

[Jim L.]

Just to confirm, you are continuing to add biocide?