car wont start!!!

[johnson]

1991 fwd turbo 5 speed

what does the boost gauge represent before car starts?
this is the stock boost gauge...
when its reading zero or positive, while cranking, it will fire in the engine?
when it reads negative when cranking, no fire at all?

does anyone have this problem?
what is it?

mpi relay also clicks right away then boost gauge is all the way negative?

i replaced coolant temp sensor with another one already, not new...