Question about getting air out of fuel system

[rosenfe]

82 diesel wagon. I changed both fuel filters ,then no start, obviously air in the lines. Primer pump leaking like a sieve when pumping. I’ve ordered a new one.My question is it usless to get air out without working primer pump?will pumping primer pump be enough, or do I also have to o loosen injector lines.
What is the procedure for loosening injector lines? Doi only slightly loosen and do all need to loosened at once?

[rosenfe]

I meant fuel lines at the injectors

[Shern]

Did you fill the secondary filter with fuel?
If so, even with a leaky primer, you should still be able to start the engine.

Crack each hard line at the injector, bump the engine until you see fuel dribbling onto each respective injector, tighten dribbling lines. Start engine.

[rosenfe]

Yes I filled filter with fuel from old one, but it did not fully fill it. Would it be helpful to take it off and fill to top, though I think with new primer I pump ininstslled,it would fill up. I’ve pumped and pumped, loosened first injector line, but no fuel coming out. I also cranked motor with injector line open- no fuel dribbling out

[engatwork]

Make sure spin on filter is all the way full before install. Loosen all of the injector lines. Prime/pump and crank over engine till you start getting fuel out of injector line closest to firewall. Keep it up till you get fuel out of next line then snug it down. If it is a healthy engine it should start and run on 3 or 4 cyls after which time you can tighten down the remaining lines.

[Diesel911]

I like to loosen all of the fuel injection lines at the injectors, but others don't.

So, there is 2 systems. Air in the fuel supply system is supposed to go out when you use the hand primer of you pump it enough. When you hear a squishing or squeaking sound coming from the fuel injection pump the air is out, but you still pump more to make sure.

If you have the old type of primer with the bare aluminum body pump you need to push the plunger all the way down and screw it to tighten it down. In theory that should seal off any air.

The fuel injection lines are the high-pressure part of the system and if air is in there the air compresses a lot, but the fuel only moves a tiny amount. So, you are loosening the fuel injection line nuts at the injectors to let the uncompressed out.

[Shern]

To be absolutely clear, you can prime until the heat death of the universe and no fuel will ever come out of those injector lines.
The only way that will happen is by cranking the motor. Priming will only fill the low pressure portion of the fuel system. The high pressure side requires the articulation of the pump itself.
Ergo, you need to crank the motor until those lines dribble. Then do as I posted above.

[Diesel911]

Originally Posted by Shern

To be absolutely clear, you can prime until the heat death of the universe and no fuel will ever come out of those injector lines.
The only way that will happen is by cranking the motor. Priming will only fill the low pressure portion of the fuel system. The high pressure side requires the articulation of the pump itself.
Ergo, you need to crank the motor until those lines dribble. Then do as I posted above.

As I said it is 2 systems. The low-pressure fuel supply system and the high-pressure system.

If you did not beleed the air out of the low-pressure fuel supply system, it gets into the high-pressure system where it gets trapped in the fuel injection lines.

[rosenfe]

Thanks all for the help. After cracking injectors and lots of cranking it started. Thanks again