L4150 bleeding

[Craig McMillan]

I ran out of fuel Christmas Day and have been trying daily to bleed the injectors.
It's a 5 cylinder and the 2 injectors furthest from the seat have good flow, the next three I seem to be getting no flow out of.
I watched vids and read lots of posts, but have yet to find mention of the thumb screw to the right of the fuel filter...it's very similar to the one closer to the front of the tractor which I assume is the injector bleed valve.
Any tips?

 

[1970cs]

#70 knob open it up and I usually take the hose to watch 100% pure fuel. Then hook up hose close knob and then crack each injector line at each injector till you get the unit to run.

Pat

 

[Craig McMillan]

Thanks Pat, just plugged in block heater...will update in a few hours

 

[Craig McMillan]

Hey Pat, that did the trick...disconnected the hose and fuel ran out and wouldn't stop...cranked the engine and could see pump working in solid spurts...reconnected hose, cranked again with that thumbscrew open for a few seconds, then closed it. Got up on tractor and bled the five injectors, front to back...this was the first time I had any spray out of 3-5 injectors...tightened them all up...60 seconds of glow plug...started first time! That's definitely the way to do it on this tractor at least. Thanks for your help!

 

[rbargeron]

Hi Craig - glad you got it running ok.

Next time it runs out of fuel, fill the fuel and try just opening the #70 knob without opening any injector pipe fittings. I think you'll be happily surprised to see it fire on one cylinder , then two, etc and run - roughly at first, then better. As it smooths out, close the #70 knob and it should run just fine. Kubotas have had these air-purge setups on their engines for many years. Assuming the short rubber tubes are in good condition its easier than loosening fittings. Dick B

 

[Craig McMillan]

That #70 knob is still a bit of a mystery for me. I've ran out of fuel maybe four times over 10 years, and found the orange tractor talks with Vic where he mentions that as possibly being an easy fix. One time I was on the way home from a parade and had it towed to kubota for service. They charged an arm and a leg to bleed and said it was a hard model to start. By contract, the pulling of the house downstream from the lift pump dig the trick as far as getting fuel into the 3-5 cylinders for me. As in first try start after quick injector bleed. What may or may not had an effect was that that hose, was pretty bent for me at the top...it was 7.25" long...I put on a new one that came 24" long...I'll trim it at a later date. A 5/16" one seemed to fit.

 

[kubotaken]

I have a 1987 4150. When I have to bleed the system after a filter change I remove the return line to the tank and use a bottom of a ball point bell and a rubber bulb off a anti freeze tester. I stick the small end of the pen bottom in the hose and then using the rubber bulb suck the fuel back the return hose. It may take a few attempts, but as so as the fuel comes out the return hose re-attach and the tractor starts every time.