Injectors not firing?
 

installing the rebuilt engine into my S5 T2. Everything is stock. Got spark, fuel pump is working, filled up a jar with gas in about two seconds at the inlet to pipe that goes to the pulsation dampner. Engin cranks, but no start. Killed a battery cranking it, charged it and killed it again. Sprayed starter fluid in the filter box and it acts like it's going to start until I take the key off crank. Di the part wher you jumper the connector to fill the fuel system back up. Nothing...zip. Should I at least smell fuel from an overly crank car with know start? No Check engine lights. Even if I crossed connectors on the primary and secondary injector, one of the sets ought to pumping fuel into the engine. I got nothing. Checked connectors on the ECU and they are fine. Can't find any disconnected wires of vacuum lines. Any ideas?

Spray starter fluid at the throttle body and see if it will start now. Also, spin the CAS by hand and try to hear for clicking of the injectors.

have you pulled the plugs to check for fuel on them?
if bone dry, back probe the injector circuits at the ecm. check for battery voltage KOEO at the primary pins

if no voltage, the most common cause is backed out pins at the injector connector(s). those connectors get very brittle given their location, and if disturbed, can easilly break the locking tang(s)

the S5s don't have such a bad problem with the injector connectors as the S4, those are horrible.

with the pump connector jumpered it will only turn on the pump with the key on.

check the ground under the upper intake manifold to the rear rotor housing, without that you get nothing for injectors.

if all that checks out simply disconnect the AFM and try to start it, if it chugs or starts and stalls then try finding a known good afm to test the car with. if that fails try disconnecting the TPS and try again, also keep in mind the injectors won't kick if you apply more than 30% throttle with it connected.

generally if the ecu has power, and sees an rpm signal it will fire the injectors, so default tends to be flooding.

however if you have spark, that means the ecu has rpm and power. if there is no fuel, you should be able to squirt some flammable liquid into the engine, and get some kind of fire.

the next step depends. easiest is probably to plug in a CAS and spin it with the key on, you should hear the injectors clicking. if not then next you check them for power, ecu is easiest i think. if there is power but they don't work, you need to manually give the injector power and ground, sometimes they stick.

if the injectors work, i'd look at the pump. the FSM has tests for volume and a dead head pressure

with KOEO, the ecm supplies voltage to the injectors. it just won't supply ground(s)
and agreed; s4 clips are horrible.

i would still pull the plugs first. start from the top and easiest. and if dry (that's the key here to not going on a wild goose chase), next easiest is to backprobe at the ecm, since you've already confirmed adequate fuel supply. that ground under uim supplies other components as well. it would be fairly easy to see how good that ground is, testing at the ecm, without resorting to removing the uim. i dunno. personally, i like to leave as much intact as possible and not immobilize things until i know i have to

i meant the pump won't turn on with the key off, even if the test connector is jumpered.

ok sorry. my bad