I'm having trouble starting up my 04 engine, it has been unused for at least a year (bought it second hand a year ago for my kart project). This is the first time I'm trying to start it.

It turns over alright on the starter motor, I can't hear any unusual sounds. Sometimes it will fire up just as you hit the starter button but it won't ever run, just a short fire. If I spray some aerostart in the intake it fires up, so I'm guessing it's fuel related.

I seem to have spark (checked with a spark tester).

I have no fault codes.

If I diagnose test the injector it clicks five times as it should.

If I diagnose the fuel system voltage it reads 12.5, as it should be.

If I remove the fuel hose from the fuel rail and hold it up above tank level and start the fuel pump, it starts to pump fuel, so the fuel pump works (at least it pumps some fuel, but I don't know if the pressure is enough).

If I remove the fuel rail + injector and try to start the engine, the injector squirts some fuel out. It does NOT create a nice cloud of fuel, is it supposed to do that?

If I run the fuel injector diagnose test with fuel pump active, i.e. prime the engine with five bursts of fuel, then try to start it, it will fire up as described earlier, but doesn't run. So I'm guessing its fuel related.

Any tips on how I could determine the condition of the fuel injector and fuel pump/(pressure) ? Or is there something else that might be faulty?