Kubota BX25 sputtering under load (not fuel filters?)

   / Kubota BX25 sputtering under load (not fuel filters?) #1  

mkoehr

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Apr 25, 2009
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I've got a problem with my BX that has me perplexed.

Last fall while mowing the tractor started to occasionally sputter and lose power, mostly when pointed uphill. A quick search here pointed to the culprit possibly being the fuel filters. Tractor has roughly 200 hrs, so I figured it was cheap to replace them both, which I did. No issues over the winter, but the tractor really only saw light plowing on a flat surface.

Fast forward to a week or so ago, and the problem has returned. I think I've only gone through about 10 gallons of fuel since I replace the filters (and yes I replaced both) so I'm inclined to think they're still ok. However, I pulled off the fuel line after the second filter (the one closest to the engine) and ran the fuel pump, I get only a slow trickle out of the line. I really have no idea what the flow should look like; should it be squirting out? Or a slow trickle?

I also pulled the line as it exits the first filter underneath the tractor to see if it could be the pump. Barely anything came out. Again, I don't know what to expect; will a clean filter impede flow that much?

At this point I'm thinking its either a clogged filter or a clogged line from the tank to the filter. Barring those, my last resort is the fuel pump. The pump is ticking like its working, but I did have an issue with my ignition a few years ago that caused it to stick 'on' (but engine off) and run the pump until the battery was drained, and this happened on more than one occasion. In other words, the pump has seen some cycles....

Can anyone chime in with some thoughts on what kind of flow I should be expecting pre-fuel pump and post-fuel filter to the engine? Any other recommendations of things to look for before I go buy a new set of filters and fuel pump?!
 
   / Kubota BX25 sputtering under load (not fuel filters?) #2  
Disconnect the line between the tank and first filter. If the flow is good, replace the first filter again. (good flow is a good solid stream) If the flow is only a trickle from the tank, you may have on obstruction in the sump of the tank. A quick blast of air should return normal flow...at least for a while.
Make sure that the pump is making a clicking sound with the key on. With the fuel line disconnected after the last filter, turn the key on, the pump should click rapidly and there should be substantially more than a trickle.

At around 200 hours, my BX23 lost power and I found that the first filter was filled with what looked like rusty mud. I have changed the first filter fairly often since.
 
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   / Kubota BX25 sputtering under load (not fuel filters?) #3  
Are you using the recommended fuel?
How old is the fuel?
How long has the oldest fuel been in the tractor tank?
In what container is the fuel stored?
What weather/temperatures/humidity has fuel been subjected to, in storage and in the tractor tank?

Personally, I change fuel filters and two HST filters every 100 hours. I can't afford down time.
I never buy more than two weeks diesel at one time, which is two, five gallon cans. I do not add the new fuel until most of the old fuel is gone.
My tractor fuel tank access is on top of the hood. I carefully remove the cap and wipe around the cap and the threaded portion on tractor with a paper towel so dust/dirt does not fall into the tank.
 
   / Kubota BX25 sputtering under load (not fuel filters?) #4  
I bought a used G1800AWS and it had a leaf in that gas tank that would get over the outlet and stop the flow of the fuel. I removed the tank and removed the leaf and that was the end of the problem. Something for you to check, There should be a good flow from the tank to the first filter.
 
   / Kubota BX25 sputtering under load (not fuel filters?) #5  
...I do not add the new fuel until most of the old fuel is gone....
Isn't it better to keep the tank full to reduce condensation? Condensation provides a growth environment for algae I believe. That algae could clog the fuel filters as well.

That is just my understanding. I could be wrong and am not a mechanic... or even close.

I think water in the fuel has got to be one of the biggest issues for diesels. Is there a fuel/water separator on these things? I just purchased a BX25D. I haven't even physically seen it since it got delivered to my property 7 hours away from me... but my buddy seems to be enjoying it :) I read the manual and didn't see a FWS. That seems odd from a diesel perspective.

Oh well. Good luck on this. Sounds like something in clogged somewhere which is hopefully an easy fix.

Chris
 
   / Kubota BX25 sputtering under load (not fuel filters?)
  • Thread Starter
#6  
Disconnect the line between the tank and first filter. If the flow is good, replace the first filter again. (good flow is a good solid stream) If the flow is only a trickle from the tank, you may have on obstruction in the sump of the tank.

This was going to be my next step. I ran out of daylight last night to take off my bro-tek skid plate to get access to the fuel line between the tank and the first filter. I'm hoping this is where the problem is; when I disconnected the line coming out of this filter and into the fuel pump, I really didn't even need to clamp the line, since almost no fuel was coming out. But I'm not sure how much flow should be coming out of the filter with only the weight of the fuel in the fuel tank pushing it through the line and the filter. I'm assuming the filter adds some resistance, so I wouldn't expect a steady stream, but it still seemed like too little flow.
 
   / Kubota BX25 sputtering under load (not fuel filters?)
  • Thread Starter
#7  
Are you using the recommended fuel?
How old is the fuel?
How long has the oldest fuel been in the tractor tank?
In what container is the fuel stored?
What weather/temperatures/humidity has fuel been subjected to, in storage and in the tractor tank?

Personally, I change fuel filters and two HST filters every 100 hours. I can't afford down time.
I never buy more than two weeks diesel at one time, which is two, five gallon cans. I do not add the new fuel until most of the old fuel is gone.
My tractor fuel tank access is on top of the hood. I carefully remove the cap and wipe around the cap and the threaded portion on tractor with a paper towel so dust/dirt does not fall into the tank.

What do you mean by 'recommended' fuel? I'm using diesel that I get from the big-name gas station up the road from my house. I don't believe they use any bio-diesel blends, but I'm going to double-check on my way home.

My diesel doesn't get used up every two weeks, but I don't think it ever gets older than 2 or 3 months. I add some powerservice during the winter months, and I just used the last of the diesel that I bought around March/April.

Fuel is stored in 5 gal metal cans, and is stored in a garage with the tractor. Stays warm enough in the garage that I never have gelling issues, or any issues starting the tractor. Really no humidity to speak of.

I like the idea of replacing the fuel filters every 100 hours, and I think I'll start doing the same. I agree that it is cheap insurance.
 
   / Kubota BX25 sputtering under load (not fuel filters?)
  • Thread Starter
#8  
I think water in the fuel has got to be one of the biggest issues for diesels. Is there a fuel/water separator on these things? I just purchased a BX25D. I haven't even physically seen it since it got delivered to my property 7 hours away from me... but my buddy seems to be enjoying it :) I read the manual and didn't see a FWS. That seems odd from a diesel perspective.

Oh well. Good luck on this. Sounds like something in clogged somewhere which is hopefully an easy fix.

Chris

Thats one of the reasons I like the Kubota- I have yet to come across something that wasn't an 'easy fix'. I reached out on this one since the 'easiest' fix (replacing the fuel filters) didn't seem to fix the problem, although now I'm not so sure that it may have just clogged again.

There's a good thread here on installing a Racor filter in lieu of the first filter, which I think I may look in to.
 
   / Kubota BX25 sputtering under load (not fuel filters?)
  • Thread Starter
#9  
I bought a used G1800AWS and it had a leaf in that gas tank that would get over the outlet and stop the flow of the fuel. I removed the tank and removed the leaf and that was the end of the problem. Something for you to check, There should be a good flow from the tank to the first filter.

That was a thought of mine as well. I didn't have time to take my skid plate off last night to get access to the line entering the first filter (I could only access the line between the first filter and the fuel pump), but I figure that doing that will point me to where the problem is. Good flow from the tank = clogged fuel filter. Bad flow from tank = clog in the tank.
 
   / Kubota BX25 sputtering under load (not fuel filters?) #10  
If you do blow back through the hose to the tank, be sure and remove the filler cap first or you'll get a good diesel bath as soon as you remove the air hose.:eek::eek: I remember reading about someone doing that.:laughing:
 
 
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