Long time user but this is my first post. So I have a 1987 gxl that I just put a 87 tii Jdm motor in, My current problem is that when I start the car it will rev up to about 2k (backfire sometimes) then falls on its face the second I touch the gas. Although about a week ago I put the first fresh gas in after the swap and was able to keep it alive long enough to drive it down the street and back but now it’s acting how it was when it was starving for fuel (just looked in the tank and have considerable amount of gas)

 

I had a very similar issue to my T2 swapped FC if not done already first id recommend, fuel pump voltage test if that is good then check for fuel at rail if none than most likely your pump (good excuse to upgrade pump anyways you will need it.) but you can try jumping the test connector to eliminate the possibility of the relay aswell or it could be a vac leak causing the AFM to kill the pump if you hold the flapper door open on the afm and get someone to crank it should bypass the safety switch. my car was unlucky and i ended up having both a vac leak and dead fuel pump new pump let my car start but would died if i touched the throttle found a loose coupler and it fixed it hope this helps you

 

Being its a jdm engine i'd be compression testing it. Rare when you get a good engine from across the pond

 

Try getting a gauge tapped into your rail and watch what your pressure does. Seems like a good place to start is the pump. Either it works or doesn't. Then move out from there electrically and then check flow path.

 

you said you installed this engine?..did you wire it up too?..
I had a situation where the wiring of the injectors was not exactly correct and it did what your is doing,back fire when you hit the throttle,run ok then die..all sorts of weird ****.
If I recall it was the secondaries being swapped in their places and therefore you would have a #1 rotor with it's primary BUT have a #2 Secondary injector..
Took 3 weeks to figure out but I got it.

 

the fuel lines were reversed.