tricky no start problem..

[MrIgor]

Today I finished installing new transmission, the engine cranks BUT ONLY starts for a sec if i spray starter fluid into throttle body (quickstart) and dies right away. Looks like I have no fuel BUT The most confusing thing is in the fuel rails there is fuel if i press the release nipple.

It started before like clock work, no problems ever before I replaced transmission. it cant be a wiring thing, because I have spark, and NO check engine codes.

How can it be that I have fuel in the rails, and spark and wont start???