I started with a brand new Bosch from VW heritage but it failed before I even drove the bus! They wouldn’t take it back because I’d bought it over a year ago. Instead they sold me an el cheapo Chinese one that had been verified working by their experts. I wasn’t impressed as I’ve literally spent thousands with them. I’m going to check the wiring etc and if that is sound I’ll just get the Bosch rebuilt by the fella @theBusmonkey recommended. Are you putting the FI engine back in when you’re finished painting?