f2680 running problems

   / f2680 running problems #1  

Riktar

New member
Joined
Apr 27, 2014
Messages
12
Location
Neosho, WI
Tractor
John Deere 4400
Have had an intermittent running problem as of late. During full throttle with the deck engaged the will start to lose power. There is no pattern to it and sometimes I can cut all day and other times it starts to act up every 5 minutes.

Oil/filter has been changed, replaced the fuel filters (even though they are not due for a change), put a new air filter in and same problem.

The only thing I have noticed is the fuel pump does not run at a constant rate, IE: it usually makes a even sound when I turn the ignition on. Obviously I can't hear it how it sound when the engine is running.

I thought electric fuel pumps were either work, or not work so I am hesitant to just buy one because it sounds like its not working.

Any thoughts?

I will add that a couple months ago I had a problem with one of the employee's putting gas in the mower :eek: and then asking me why the engine would not run,,,,,,,,,

That was a whole bunch of fun, flushing the tank and fuel system,,,,,,,,, :mad:

Could that have damaged the fuel pump or something else in the system? It was running fine after spending more time than I care to mention flushing out all the gas,,,,,,,
 
   / f2680 running problems #2  
When you flushed the system after the gas experience, is it possible you left one of the lines or clamps loose so that it could be sucking air on the suction side of the fuel system? What you're describing could be air in the fuel. Sometimes bending an old fuel line can cause it to get a small crack that you can't even see. That's pretty easy to diagnose, just replace the last piece of fuel line in front of the injector pump with clear plastic tubing and look for air bubbles. That would eliminate a problem caused by disturbing the fuel lines and filter. I would also check the vent on your fuel cap to make sure you aren't getting a vacuum in the tank.

The fuel pump probably wouldn't be damaged by some gas, and the fuel pump on most tractors doesn't do very much because the tank is normally a good bit higher than the injection pump so it runs at very low pressure, usually only a pound or two. So if you fill the tank you almost don't need the fuel pump.

Gas can do a fair bit of damage to a diesel if it's in a high concentration. There's two sources of damage, one is from the gas detonating and causing higher than allowed pressure spikes at the wrong time. The other source of damage is gas doesn't lubricate as well as diesel, so it can damage the injection pump. I would suggest the following to further diagnose the problem. Carry the size wrench you need to remove the fuel line from each fuel injector whenever you use the tractor. The next time you have this problem, leave the engine running, and crack the fuel line on each injector so that just a tiny bit of fuel can leak out. That should cause a change in sound and speed of the engine. If you find a cylinder that behaves differently than the others when the fuel line is cracked, you've narrowed down the problem to either the fuel delivery for that cylinder, or some mechanical problem with that cylinder. After that I'd think about doing a compression test to confirm each cylinder is OK. If so you'll need to check the output of the injection pump.
 
   / f2680 running problems
  • Thread Starter
#3  
Thanks for the suggestions. I will try the clear hose between last filter and pump. I did try cracking the lines feeding the injectors and in all cases the engine noticeably slowed down. The back cylinder did spit out a bit of "foam" instead of fuel when initially cracked.

Fuel cap question: This thing is vented? So when I unscrew it from the filler neck I should not hear any type of air movement from pressure equalizing?
 
   / f2680 running problems #4  
The back cylinder did spit out a bit of "foam" instead of fuel when initially cracked.
I've seen that foaming you describe but have never understood if it really meant there was air in the line, or if the fuel was just making bubbles because of the way the fitting was cracked open. Were you able to do the test while the engine was exhibiting the problem you described? Did you do this with the engine running at some significant RPM? If it's only idling, sometimes it's hard to tell if a cylinder is doing much or not. Ideally you'd like to have a load on the engine while you crack the fuel line. If you could get a helper to lift a heavy bucket full with the FEL while you crack each line, that would be the best test.

Fuel cap question: This thing is vented? So when I unscrew it from the filler neck I should not hear any type of air movement from pressure equalizing?
Yes, all fuel systems have to be vented, it's usually in the cap. If you examine the cap you will probably find a small hole in the side somewhere, they used to be on the top but that's not so common anymore. In your case the problem would be that a plugged vent could create a vacuum in the tank, preventing fuel from reaching the fuel line and fuel pump.
 
   / f2680 running problems
  • Thread Starter
#5  
So if I were to run it with out the cap (I would cover it with a towel so nothing gets in or out but would provide venting) and the problem goes away, then its a simple cap replacement? That would be easy. And I am not used to anything being easy,,,,,,,,,,,, :)

I have tried doing the line crack when it the problem occurs but I am never fast enough to get to set the brake, get off the mower, lift the cowling and finally crack the line(s) without the motor smoothing out beforehand.

Going to cross my fingers my towel experiment resolves the whole mess,,,,,,,,,,,,,,,,
 
   / f2680 running problems
  • Thread Starter
#6  
Well I will be dipped in (insert vile substance here),,,,,,,,, the Kubota has been happily running for the last 3 hours without a hiccup. I will be picking up a new fuel cap from the dealer tomorrow when they open.

Thanks BeezFun!!!!!!!!!!!!
 
   / f2680 running problems #7  
Well I will be dipped in (insert vile substance here),,,,,,,,, the Kubota has been happily running for the last 3 hours without a hiccup. I will be picking up a new fuel cap from the dealer tomorrow when they open.

Thanks BeezFun!!!!!!!!!!!!


:laughing::thumbsup: that was good.:laughing:
 
   / f2680 running problems #8  
Well I will be dipped in (insert vile substance here),,,,,,,,, the Kubota has been happily running for the last 3 hours without a hiccup. I will be picking up a new fuel cap from the dealer tomorrow when they open.

Thanks BeezFun!!!!!!!!!!!!
Be interesting to know what plugged the vent. If you wax the tractor, or use that liquid wax stuff you spray with the hose, that might do it. Maybe dropping it on the ground could get some dirt in it. I guess it could also be insects taking up residence under the edge of the cap. Anyway, hope it keeps running well, you got off really lucky. That's about the cheapest repair you could possibly have.
 
   / f2680 running problems
  • Thread Starter
#9  
When things settle down around here I will try and disassemble the old cap. I am interested myself how something so small/minor can make such big problems,,,,,,,,,,
 
   / f2680 running problems
  • Thread Starter
#10  
Well a new year and the same old problem is starting to surface. After a solid month of mowing with no problems, the old intermittent stumbling problems are back. Tried loosening the fuel cap to check if the cap was plugged. No dice. Same stuff.

Anyone ever pull the fuel tank on a f2680? Just for the sake of checking the outlet on the tank, maybe some build up of junk is forming?

This thing acts like it is fuel starved with not much rhyme or reason to it.

NUTS!!
 
 
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