‘00 Golf TDI (air in fuel system)

Per suggestion online, me and and a friend tried cleaning the manifold system (including changing all the hoses) which had tons of gunk in it and swapping out the fuel pump. Still we seem to be getting air in the fuel system over time and it gradually has issues starting. We then reprime the fuel system and the cycle repeats. Any help appreciated. Thanks.

You have an air leak in one of those hoses or connections. A common place is at the O rings on top of the fuel filter. That might be a place to start, however since you removed and cleaned/replaced so much it very well could be elsewhere in your case.

Edit, I reread and see you cleaned the manifold system. Not the fuel system. Chack the fuel filter O rings and check to see if you have any leaks at the injection pump. Check for damp areas under, around and behind it you might even need to employ a small inspection mirror.

Put clear lines, if you don't already have them, in Between the filter and the pump so you can see where the air comes from.
If you're getting bubbles before the pump it could be the o-rings to the hard lines, or the filter

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mattgf1123 said:

Per suggestion online, me and and a friend tried cleaning the manifold system (including changing all the hoses) which had tons of gunk in it and swapping out the fuel pump. Still we seem to be getting air in the fuel system over time and it gradually has issues starting. We then reprime the fuel system and the cycle repeats. Any help appreciated. Thanks.

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Most common to have a few air bubbles in the clear line,the solution is to replace the filter's o'ring for the return tee.
best way to resolve this is to use the Deitzel mod or a nicktane uber filter kit.
It sounds to me that your check valve is going bad. its located at the tank pickup.

as for your other statement about cleaning the intake manifold, i hope to god it was not very bad in the head. Many owners who do this and do not clean the intake ports on the head end up with engines that blow up. Now that you have a clear path way to let more volume of air in, this breaks off the bits you did not get that are trapped in the intake runner and they get wedged against the head and the piston and or the valves. This kills the engine

Thanks everybody for the help. Giving up and taking it to a forum suggested mechanic