Air bubbles in fuel lines

[zagarus]

So I had my car running today again and I noticed a good amount of air bubbles traveling through the lines between the filter and the pump.  Would it be a safe assumption to say that some of my fuel lines may not be tight enough?  Is it really bad to have this happening?   Car seemed to run fine so I am unsure.

[RabbitJockey]

yeah somethings not tight enough, and you won't notice much difference in performance if you let ur car sit for a while it might be harder to start, whether its warm or cold out, its definitely something to address and is usually an easy fix

[fatmobile]

Air in the fuel is usually caused by a restriction in the fuel line.

The vacuum created draws air out of the fuel,
 Is there more air when you rev it?
Where is the air? just after the filter?

A vacuum gauge connected to the fuel line will let you know if:
 your fuel is gelling,
 tank vent is clogged,
 tank screen or check valve is clogged,
 Orrr if your filter is clogged.

Way before you are stranded beside the road.
Every one of my cars have one on the dash.

[zagarus]

I wonder if it's the warmer valve on the fuel filter. It never quite seemed tight enough.

[VWDoc91]

Check your fuel filter spigot. You'd probably notice the diesel leak below the filter- it tells you that the plastic spigot cracked or tore off. Just unbolt the filter loop and turn the assembly upside down so you can see the spigot. If you feel it "stripping" or you tighten and the spigot still leaks- it's the broken or cracked spigot. Use a standard bolt (M6 with 13mm hex head, I think) and a spigot gasket to tighten it, and you won't see the air bubbles anymore. That was what I did when I drove a 300-mile trip to a football game, and already had completed 500-mile run when it happened. The idle was horrible, but runs fine in speeds of over 1400 RPM.

Zagarus, if the filter isn't leaking, then you need to find the source between the tank and the filter. You would never know if the fuel line has a micro-hole, unless you look.

[VWDoc91]

Hmm. The more I think about it, has any connections required the use of copper washers? If so, check 'em. Especially if the ends have banjo fittings.

[zagarus]

all copper seals on banjo fittings are new and not leaking (ie on the pump)  Everything else has clamps but I will recheck them. Fuel filter is also brand new. 

[79rabbit4dr]

I'm not sure where you're air leak is BUT...

If you have original rubber hoses they might just be dry and cracked at the fittings, an easy (free) way to fix it (for now) is to just cut the tip off of the hose and reattach... assuming you have sufficient excess.

My return lines between injectors were leaking and while I was waiting for my new hose to arrive in the mail, I just cut the tip's off and reattached... survived a 400 mile round trip and then some.