Strange issue RB25DET wont start

[jtha7]

Hi all,

Im sorry for the long post im hoping someone may have the solution to my car not starting. Ive been restoring a 1994 R33 GTST (Series 1) for a few months. 

The Issue: 

- When everything's together on the fuel rail the car cranks but wont start.

- but when I disconnect the fuel pump and hold throttle open it will be hard but it will start. I can then put the plug back on and the car will run normal. If i turn it off and try again it wont be able to start.

- this first started when my mechanic and I put the intake back on (after fixing coolant leaks), then for some reason when I changed a fuel dampener on the return line the Issue temporary resolved but came back a week later.

 

Things about the car:

- it sat for about 4 years but was able to start and run (it had a coolant leak back then which was from corrosion. All cooling system has been fixed)

- replaced the old fuel and the fuel pump as it stopped working, i replaced it with the same size fuel pump it had which was a walbro 255 

- alot of things have been replaced, timing belt, splitfire coilpacks, spark plugs, Rocker gaskets. Basically alot of things have been refreshed and the car was running fine.

- It ran for a week well after replacing the fuel dampener. Then same issue arose. I replaced FPR with a SARD FPR, also replaced the injectors and rail (also verified that the injectors were working), checked spark looks ok (maybe a bit weak). Ive cleaned up all the grounds too.

- ive tested all the lines (return and inlet are not blocked.)

 

I've heard that it could be fuel pump losing voltage during cranking? (I can ground the grey wire on the fuel pump plug) but this doesn't make sense as ive got constant fuel pressure on my gauge and the car will be able to start when there's no fuel going into the rail (it can start also if i just run inlet into the return). So i think this points to too much fuel/not enough spark.

At this point im thinking to just recheck my grounds and possibly any sensors.

Please share any help. TIA

[Murray_Calavera]

What ECU?

[jtha7]

Stock ECU