No fuel coming out of injectors

[MonkeyFella95]

So to update everyone I realised I really rushed to judgement on the FD and PPR (Sorry Arran). I've not sent mine back for a replacement because I wanted to test to know definitively what the cause is, so far I really don't know what to make of the results.

With the fuel supply line disconnected from the FD I get good flow from the pump. With the fuel supply connected and the fuel return disconnected from the hardline I get good flow out of the FD (although after 20 seconds I started hearing strange metal sounds and the pump get louder so I disconnected the pump quickly to avoid blowing anything else up). If I disconnect one of the injectors completely I get no flow at all and when I press down on the intake I get progressively more fuel, so not an issue of the CO adjustment.

All of this is exactly what I would expect if everything is functioning except the injectors still never open and it seems that when the supply line is connected to the FD pressure starts building up. I'm going to replace the fuel pump lines, which I've not touched yet, over the weekend and test the flow out there back to the tank. Although because of the noises it made with the return line disconnected from the hardline it seems like the issue must be something in the engine bay.

Totally out of ideas on the cause of this, doesn't seem to make any sense. It could still be the FD / PPR. I'm going to test with a fuel pressure tester over the weekend as well so will have more data then.