Fuel pressure issue

[Tangelos]

Hey everyone, I installed my freshly built engine last night and was having trouble keeping it running. It ran for about 30 seconds on its own then died due to no fuel pressure.

It has a brand new walbro 450lph pump rewired to the battery using this method. I depinned and rewired the in-tank wires that go to the bulkhead connector as well.


I am able to prime the pump by jumping the diagnostic box with the key on. I can also hear the clicking noise in the engine bay while doing this. My fuel pressure goes up to 50-60 psi (I need to adjust it to 40) and stays there, but as soon as I start cranking the engine, the fuel pressure drops to 0 and doesn’t build until I jump the diagnostic box again. All of my wiring is standard except for the fuel pump to battery wiring, the relay box relocation up front, and I also removed an old anti-theft system and repaired the lines (re connected all of the spliced lines). Should I start looking there?
it seems like the fuel pump isn’t getting any signal at all when the engine is cranking, has anyone had this problem before?

 

[MKZ7212]

Presume you have this?

 

[Tangelos]

Yes I do, I have seen people remove the fuel pump relay and bridge these two connections circled in red, but i don’t want to go through with that if it hurts the fuel system

 

[a.tapos]

If you nick the earth pump trigger direct from the ecu it removes all the factory crap and gives you alternator/battery voltage.

 

[a.tapos]

I think on mine i used the live at the pump as the trigger then earthed out a relay and wired up to my battery as its in the boot.this only works if the factory wiring is good.