Quote Originally Posted by MonkeyFella95 View Post
At this point I'm mainly concerned about the pressure building up. If I don't sort that out I don't have the time to calibrate the mixture. The injectors don't spray at all even with the flap fully down and with the injectors off fuel starts flowing as soon as any pressure is put on it. Maybe I've put too much focus on that, if it's unrelated to the issue of pressure building up then I'll deal with it later.

By out of ideas I meant out of ideas on the cause, not out of ideas for tests. I'm going to do a working and system pressure test this weekend which should be telling, I've not had a test kit until recently. I certainly should have done that before my fuel lines exploded but I didn't expect that to happen, expensive lesson learnt!
Then connect a fuel gauge on your system and test the pressures. You should see 60-75PSI with the valve closed on the fuel pressure tester.

One place to look at is the fuel accumulator. Pull the small hose off the end of it (leave the two larger connections alone), some fuel should come out from there, that's normal. If you have another piece of hose that is the same diameter, slip it over the nipple of the accumulator and point it downwards into a pail. Jump start the RPM relay to get the fuel pump going. You should see some fuel come out of that nipple for a few seconds and then stop. If it does not stop and it is coming out like a garden hose after about 5 seconds, then the diaphragm inside the accumulator is damaged and it needs to be replaced.

Also, did you pull all the injectors off, jump the fuel pump, press down on the flap and see if fuel is coming out from the ends of the fuel inject hoses? If so, was fuel coming from all of them?