wish I could help more. I would doubt that you need to undo the other screw. The schraeder valve in the pump should be adequate to release air and/or fuel. That said I've never done this myself. Good luck.
I just went through this last week. EXACT SAME SCENARIO- Replaced the lift pump and boom! Good to go. I all i can think of is that the pump was to weak to prime the system. I was having hard start issues... long cranking times with no fire
That's why I fill the fuel filter canister 3/4 full of clean fuel before installing a new filter & o-ring.
Now ya gotta go through the priming drill.
Looks like you need to shed the air in the injectors & lines.
To prime the system,
Charge the batteries, you're gonna be calling on them.
Be sure the fuel filter canister is full of fuel.
Disconnect the battery charger...very important.
Turn the keyswitch just enough to "bump" the starter to get The Free 25 Second Lift Pump Run.
Your lift pump pressure gauge should show 10 psi or greater.
Loosen the fittings on #1, #3 & #4 injectors with a 3/4" open end wrench.
Crank the engine for 10 seconds then check and tighten any wet, dripping fuel injector fittings.
Repeat the 10 second cranks & tighten the wet injector fittings until the engine kicks, trying to start then tighten the remaining loose fittings and start the engine.
You can prime the filter by bumping it and cracking the 18 pipe plug on top of the filter bracket and then do the same at the return line on the VP. Do that and crank on it some and it will like start. If it stops once crank it a bit more again and it will usually start without having to do the injectors unless it has been sitting with an open system. Do it like brakes where you close it while it is pumping out so air does not get back in it.
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