2000 VW Beetle TDI ALH starting issues

Just purchased a Beetle with the ALH TDI. previous owner told me it had a no start condition after belt was changed. So figured it’d be an easy fix.
Got everything timed, but dang thing won’t start. Replaced 109 relay, no start.
Bled the pump with a mightyvac vacuum pump. But when I go to bleed the injector lines, there are a lot of bubbles. I hooked up an electric pump to the injector pump, so have plenty of fuel going to the IP, got the engine to where it would chug, but won’t fire off and run. Seems to still be bubbles when I crack open lines.
What could be the issue? I’ve also jumpered the shut off solenoid to 12v, still same issues. What in the pump could cause air to still be in the lines?

Could the shut off solenoid cause air to somehow get in there? Maybe that little plastic piece stuck?

Maybe not the problem but check the air shutoff valve that is before the intake (I had this on 1999.5 MK4 ALH) and make sure it is opening. I randomly had mine stick closed and car would not start when done work but ran fine that morning. Just a thought

Checked that as well, it stays open like it should.
I pulled the shut off valve out and pulled the spring and plunger out, but the starter decided it wasn’t happy with life and died. Got another one in, so going to bolt it on and see if that plunger is what has been causing the issue.

I’m thinking the pump is shot. I don’t get a good squirt of fuel out of the injector lines, I get a lot of air and bubbles.
Also, swapped in the new to me starter, and the engine is cranking over really weird now. Some grinding sounds and like a “bum bum bum” sound. Surely it didn’t do any internal damage? I double checked my timing marks awhile ago and all looks good...

So after a LOT of troubleshooting, and new parts, the beetle runs!

First, purchased a new battery as the one I had finally croaked.
Attempted starting but after a while, some strange noises popped up. Pulled starter as all of a sudden it stopped spinning engine but would spin itself. Chewed teeth off ring gear of torque converter... purchased new converter, installed, back to troubleshooting. Now starter number 2 won’t spin engine over... just spins and spins. Pulled, no obvious signs of damage, went ahead and ordered remanned unit.

Before the converter/battery/starter issues were taken care of, I swapped out the injection pump. Still not much fuel being pushed. So primed and primed with electric fuel pump.
After staring at a photo of the fuel lines on a timing thread on a tdi forum, I noticed something strange. Snap shot the photo and went to my engine. Sure enough, previous owner had swapped number 1 and 2 injector lines! I was fighting a losing battle since the beginning! Got that corrected but then all the converter/battery/starter problems popped up.

After new starter was installed, had my assistant crank while I bled lines and all of a sudden, vroom! It fired up and ran on its own power!
Multiple issues from previous owner mishaps is what it all boiled down to. Timing was off due to bad timing belt change. And injector line crossing were the main culprits.

I had one that wouldn’t start cause the fuel line from the fuel filter to the injection pump had a crack and was allowing it to suck air.

I may need to invest in new ones myself before they decide to do what yours did.
I’d really like to replace them with see through style, since the beetles didn’t come like that.
Slowly but surely, this little car is getting better and better. Basic maintenance and repairing what was fudged from the previous owner has been very good for this vehicle lol.