Bad / Plugged return line will cause the injectors to over pressure and pop too fast.
Hey Wolfman (and everyone!) , I have an ongoing massive PITA issue with a B26 kubota. It runs fine a lot of the time, then will randomly just start chugging and dying, and it will be a bitch to restart.. run for a few minutes or a few seconds or occasionally 30 minutes and then stall and die again.
I have done everything I can think of:
- Drained and cleaned the tank
- I have put 2 inline fuel screens before the factory filter so I can see when there is fuel in the system.
- I thought the fuel pump itself was dying, so I added a switched 12V fuel pump *after* the fuel filter but before the mechanical lift pump the tractor uses. If I leave it running, it seems to overwhelm the system and causes the tractor to stall, however I switch it on to help restart after one of these stalling conditions occasionally. Not needed most of the time.
- I have tried the injector cleaner additives, and even pouring the injector cleaner into the air intake. This did seem to clear a bunch of gunk out.. lots of carbon bits came out of the exhaust, but it did not fix the issue.
- I thought it may be the tractor "safety switches" that stall the tractor if you stand up, or try to move with the seat backwards, etc. There were 5 potential switches that could cause a stall. I have bypassed the entire system at this point to remove it as a possibility .. so none of those switches do anything anymore. I can stand up and move the tractor, move with the seat backwards in BH mode, etc.
- I assume if the injectors are blocked in some fashion it would be a constant issue.. like constantly not starting or constantly running like crap, not this seemingly totally random bizarre symptom.
The bottom line is that the injectors are getting plenty of fuel delivered. Because it is so intermittent and random it is infuriating. I have had a couple of techs come look at it and of course the tractor won't do the stall thing if there is someone else there who could potentially fix it. It seems to happen when it's hot, when it's cold, under load, no load.. driving fast or barely moving.
So further reading lead me to look at fuel return lines. I noticed mine had a bit of surface crazing on the rubber but were not leaking.
I sent the wife off to get me to matching rubber hose, put it on, and like magic it ran like a champ for the rest of the day! Problem solved? oh hell no!
A week of running great then back to the same random issue.
I reset the lines and noticed the Autozone had given my wife vacuum hose line, which I suspected was not fuel rated.
So took all that off, and got some fuel rated line from O'Reilly's (the only store locally that had anything close to the correct diameter).
Again.. seemed to run fine for a while, and is seemingly a lot better than before, but it is still acting up.
So I wondered if anyone could help answer the following:
- Do the fuel return lines have any "inherent pressure" or do they just take excess fuel and drop it in the tank? (The reason I ask, is that it seems the stalling got worse when the new fuel line had worked loose from the nipple going back into the fuel tank). Again, given how random it is, it is hard to determine correlation vs causation.
- Can the fuel return lines be removed completely theoretically? I realize this will dump diesel all down the engine, but my question is linked to number 1 above. Do the fuel return lines have any back pressure requirements. If they are letting a little air in at a splitter, would that cause the stalling issue
- Is there anything special about the OEM fuel return lines that I should consider? Even tho I have brand new fuel rated rubber tubing on the whole system, is there something the Kubota lines would make different?
I feel like I am missing something simple. When the tractor is running well (which it will often do for a couple of hours at a time) all is good, so the injectors, pump, etc etc have to be working right, correct?
Is there anything else that would cause this randomness? Some sort of heat or level or pressure sensor perhaps?
It is driving me crazy... so if you can do anything for my tractor and mental health, I would really appreciate it!!
Please help!