My 725D Grasshopper diesel engine keeps getting air in injector system. Fuel filters good. Bled air out of lines. It ran for over 5 minutes then died. Before it ran about 10 to 15 seconds then die. when it ran for 5 minutes I thought it was fixed. Not so. The clear tube that runs to the top of fuel tank that returns fuel to tank gets air bubbles in it and my guess is that what kills engine. Seems air is getting back into lines after they have been bled. Any help on this would be great. What should I do next. Can it be sucking air back into fuel system? This is driving me nuts. Thanks for any help.
#2
cpurvis
The air in that clear tube is a symptom, not a cause. It's the return line to the tank, returning fuel the injection pump does not need. When the injection pump isn't getting the fuel it needs, there is nothing to return to the tank.
Are you sure your tank isn't loaded with contaminants that is clogging your primary or secondary filter?
I always try to put clean fuel in tank. The filters did not have anything in them at all, primary & secondary. Should their be air bubbles in the return line to the tank. Thanks very much for the help. The returning fuel to the tank has air bubbles in it, doesn't seem normal to me.
#4
cpurvis
There is nothing to stop that from happening. That is not your problem. The problem is your injection pump is not getting fuel or the system isn't bled correctly OR your injection pump is faulty.
There is nothing to stop that from happening. That is not your problem. The problem is your injection pump is not getting fuel or the system isn't bled correctly OR your injection pump is faulty.
Not much in manual about how to bled system, does it have to be done in a certain sequence & can injector pump be bled. Can you help me on how to properly do it? Thanks
#6
cpurvis
Priming methods for diesel engines vary all over the place. I'm not familiar with the Kubota engine in your Grasshopper but I can share with you the instructions in the manual for my Kubota L3000. The only difference I'm aware of is that yours has two fuel filters whereas mine has only one. See attached photo and fire away with questions.
Please note that this may or may not get your engine running. This is only the procedure for bleeding after changing the fuel filter. If the engine still won't start, you'll probably have to crack open one or more injector lines at their injectors. Just enough to let air out. Then have someone try to start the engine. After a few turns, you should see diesel fuel begin to leak at these fittings you just loosened and the engine will begin to 'hit' as it's now getting fuel. As engine speed increases, tighten these fittings. The engine should now be spinning fast enough to purge the air out of the injection system. At that point, you should be good to go.
Diesel rule #1--Don't EVER let it run out of fuel. Not only is it a PITA, the injection pump relies on diesel fuel for lubrication. Spinning it without a supply of fuel does not do it any favors.
Diesel rule #2--If you notice the engine doesn't seem to have as much power as it usually does, change the fuel filter(s).
Diesel rule #3--If your air cleaner doesn't have a restriction indicator, get one. Then, don't jack with the air filter until the restriction indicator says to, OR until a couple years have passed by. This isn't really a diesel rule but a good rule just the same. My Kubota didn't come with one but there was a boss on an air intake elbow where I suppose an optional one would go. All I had to do was drill and tap it. I used to have some diesel trucks and one of them was a 'pneumatic' truck which operated in unbelievably dirty conditions. Field reps from Donaldson and Fleetguard both said the same things--First, don't mess with an air filter until the restriction indicator says to; and second, more engines are damaged from changing air filters more frequently than they need to be. Oh, and thirdly, that the dirtiest air your engine will breathe is right after you install a new filter.
And another thing......
I had a Cat 3406B engine that would NOT start after a fuel filter change, no matter how many times you pumped the priming pump. What I had to do with it was have someone crank it while I JUDICIOUSLY squirted shots of ether into the intake. Very high risk, last-ditch method but it worked--with that engine.
Thanks very much cpurvis, you have been a lot of help. You are very knowledgeable about diesel engines. I have learned a lot by posting with you. Thank you very much.
Did you try to run the thing with the fuel cap off? Might it be a simple case of fuel tank vacuum lock? Can't hurt to try it. Did you hook up air line to fuel line and blow it out, TOWARDS THE TANK? I've cleared trouble on my track loader twice doing that. Thing is gravity feed thtu 2 filters to injector pump, so it self bleeds. Always fill a new filter with new clean fuel BEFORE you install it. Avoids a ton of trouble. Never, ever ever run any diesel out of fuel tho!!! Major PIA in most cases.
