Leaking injector = 35mpg…

I recently came to my 2000 Jetta TDI MK4 and it wouldn't start. I looked under the hood and there was no fuel in the intake fuel lines. I replaced them and it after priming it still wouldn't start. I finally saw where it was leaking from, it was leaking from past the injector in the return hose. I replaced that and it starts fine now, though recently it looked under there and it's still leaking, but not from the hose now, it's leaking from the injector itself. At the base. It's a little lose I believe. When I move it from side to side I can see the fuel move slightly. My question is, do you think it's the seals? Or do I just need to tighten it up? I thought I'd see what you all thought before doing anything rash. I know something needs to happen but not sure if it really needs to be taken apart of not. Thanks! Peter

Check the copper crush washer at the base. If the injector is loose and the bolt is tight (don't force it), the washer may be crushed too much or the injector holder is bent or cracked.

Btw, better to repair it - some has reported heads getting melted where blow-by at injector occurs.

^^^That does happen.^^^

A loose injector will not leak fuel but it can leak fuel at the body/nozzle joint.

Sounds like that's not your issue. You had a leak that put fuel in the gap between the head and the injector. The compression leak is looking like a fuel leak.

When you do the inspections suggested above, make sure there's no groove in the sealing surface in the head.

Jettascuba, everything seems to be tight now. I think the fuel in the cracks(around the base of the two attachment points) made it look like it was moving more than it was. When it dries up it looks normal and no movement.

KLXS, I took out the glow plug and cleaned the threads and put some anti-seize on it and put it back in. I don't see any leaking anymore. I haven't driven it much but next time I do I am going to check and see how it's doing in there. If it's all wet with fuel I will be back to hunting down the issue. I was temped to do the inspection suggested above by Jettascuba but a friend of mine told me if I did that I would have to replace the copper seal/washer for sure. He doesn't own a jetta but he warned me to check it out first. Is this something I will have to replace if I take the injector off or is he wrong?

Yes, you should replace the washers as they are crushed to make a good seal against imperfections on the injector body and head. Some people do heat treatment on them to make it crushable again (google it). I had good luck by simply revamping the washers with 2000 grid waterpaper when I had sealing issues.

Btw, my number 2 and 3's were weeping slightly, hope to have a seal after another half degree on the injector holder bolts.