6600 air in fuel system

[Lance Newhall]

Hello All
I need some help. I serviced a tractor for a customer. Changed motor oil,air filters, and fuel filter. Bleed system. Stated the tractor up ran for 5 minutes. Shut it off. Rechecked motor oil and fluids. Started back up ran for 10 minutes. Shut off. Customer called and said after running tractor for a hour and a half it started losing power. He had a friend check it. He said it had air in number 4 injector. Said it was running on 3 cylinders. Has any one had this experience before? I have been working on tractors a long time and have never had this happen.
Thank you

 

[Dieseltech]

If that injector is stuck open, there will be compression air blowing backward through the injector when the fuel line is loosened. Not common, but has happened before..

 

[Lance Newhall]

Thank you for your reply. I failed to mention. They tell me they bleed #4 cylinder and it started running fine. Could it have had air in that line for a hour and a half?

 

[RodinNS]

Not likely. More likely there's something going on with that pump element like a broken spring or bad delivery valve.
It's also possible that there's more to this than you're being told....
I'd start by checking flow from the lift pump, leaks in the lift lines, obstructed tank pickup or bad lift pump. Recheck the filter and seals, particularly if you used a napa/wix filter. Any of those are possible and will manifest in various ways depending on how much primary flow is actually there. That's the first place I'd look. Deeper issues with the pump element or injector are possible but less likely...

Rod