Sooner or Later…
It’s not a matter of if you’ll ever have to bleed the injector lines on your Kubota, it’s quite simply when. Throughout the course of regular maintenance this procedure will come up a few times and you’ll be prepared to pull this basic service job off with these tips.
Why is Bleeding Necessary?
Bleeding the injector lines is necessary when you’ve run out of fuel, or have changed a fuel filter and have introduced an air gap into an otherwise closed system. This air gap will prevent fuel from getting to the engine and will stall your equipment – not good. There are two methods to bleed this system, one using the bleed valve and cylinder head decompression, and the other involves loosening the injector lines from the injectors. Either method is a straightforward procedure.
Bleed Valve and Cylinder Head Decompression
The first method purges air between the fuel filter bowl and the injector pump. This air lock is what commonly occurs whenever a fuel filter has been changed. Open the fuel bleed valve located on the side of the injection pump by rotating fully counter-clockwise.
Next pull on the cylinder head decompression knob to decompress the engine and relieve any cylinder head compression. This photo shows the cylinder head decompression lever with the cable pull removed for clarity – ordinarily you have a knob on the dashboard and that cable attaches to the lever shown below. By relieving the compression, the engine will crank over much faster because it’s not fighting that compression which cycles the injector pump and because the fuel bleed valve is open, the line will clear of air.
Crank over the engine for 10-15 seconds, close the fuel bleed valve and attempt to start the tractor as you would normally do (don’t forget to preheat your glow plugs).
Bleeding to Top of Injectors
If your Kubota fails to start, then you’ll need to bleed the lines all the way to the top of the injectors themselves. To do this, locate the injector lines and notice where they enter the top of the injectors.
Your Kubota tractor will have either 2, 3 or 4 injector lines and all of them will require have to be burped. Using a 17mm wrench (everything is metric on a Kubota), loosen the nut holding the injector line into the top of the injector.
With these nuts well backed off, grasp the injector line and tug upwards on the line to disengage the steel line from the top of the injector. Once you’ve unseated all the injector lines, open the fuel bleed valve on the side of the injector pump (as discussed above), pull on the decompression knob to relieve the cylinder head of any compression, and then turn the key and crank over the engine.
While cranking the engine over, watch for diesel fuel to spurt out of the ends of the loosened injector lines. When you can clearly see evidence of fuel spitting from each line stop cranking the engine, close the fuel bleed valve, release the decompression knob, and tighten up the nuts holding the injector lines. Once tightened, congratulate yourself on bleeding your Kubota Tractors injector lines!
Every Kubota tractor owner will run eventually run the engine right out of fuel. Sometimes that fuel guage just isn’t big enough!
Service Department Vic