Cranking but not starting and no fuel raching th e chembers

on the Vw microbuses

immobilizer may not be the cause of no start and ripping one out without know all th ewires ti disconnect gets you a whole lot more issues

flat key fob or chip battery
possible fuel pump or spark issue

can you hear the in tank electric fuel pump pumping as you crank

you can go old school and check if you have fuel to the injectors and spark to the plugs as you crank

if the engine check light is on the engine computer will have fault codes showing you the cause of the no start

run the fault codes and look for low pressure in the fuel system. failing fuel pump

Sounds like no fuel pressure i would have someone crank it for you while you bang on the bottom of th fuel tank, if it starts fuel pump is failing. If not can you hear the pump running?

Diagnose the no spark first. Check to make sure the crankshaft position sensor is not damaged and is plugged in. Check to make sure the camshaft sensor is also plugged in . Does the car have a RPM gauge? If so, check to see if the needle moves while cranking the engine, this would indicate the crank signal is good. Also, check to make sure the ground wires got attached under the ignition module bracket. The short burst of fuel is not uncommon on an engine that is not running.

Check this link it has many causes and fixes for this.

If Th engine doesn't crank have the battery and battery cables checked for condition and corrosion. If the engine cranks and dos not start then have the systems control computer scanned for fault codes and have the fuel pressure checked.

30-40 psi. th epump should run for 2 seconds when turning the key on, then run when engine is cranking and/or running.

You will never have direct electricity to fuel pump only when running then once you shut off ignition that shuts engine off fuel pump to automatically shuts off.I would change the fuel pump sit in car turn key Th start position do not crank engine if you do not hear a grrr,,,grunt sound i would say fuel pump not functioning therefore fuel pump malfunction replace.

Did you replace the crank sensor?

Extended cranking is the first sign of a fuel problem. Either the fuel pump is now not working or you have a leaking injector, bleeding off pressure. if plugs have wet fuel on them look at injectors. If engine briefly starts when you spray carb cleaner into throttle body look to the pump or filter. Once fuel system has been checked, look for spark. If none, find out why.