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Wonder how REM handles Short Term Fuel Trim (STFT) and Long Term Fuel Trim (LTFT). What kind of numbers are you showing there? Do numbers move during idle? Do these numbers reset (128) after KEY OFF?

Check both Engine Coolant Temperature (ECT) and Intake Air Temperature (IAT) using your REM, between normal idle and high idle.

How did your actually fix this? Also, lost of source vacuum causes the ventilation system to default to defrost only.

Maybe it time for a Fuel Pressure Gauge. At least we would know there's pressure or not. Also check the spark plugs again for wet fouling.

What about the Fuel Filter?

Does engine start with jumper and adding fuel to TBI?

Relays can fail in many different ways. Clicking means the relay coil can't hold the switching contact down on the other terminal. Does engine start with a new fuel pump relay installed?

Fused jumper wire is doing what the Fuel Pump Relay should do. Suspect Fuel Pump Relay. You said you've try a few different relay, but that jumper wire is doing the same thing. Hope engine starts.

If you have a choice, start with 15A fuse.

Also with fused jumper in place, fuel pump should be running (pumping).

Remove Fuel Pump Relay and using a fused jumper wire, connect C216_1(30) to C216_4(87) at the fuel pump relay block. Retake voltage measurement at D1_6 again.

Need to take some voltage measurements. Use the following connectors callout. D1 and D2 are located under the hood, right side of engine compartment. Should have yellow covers on them. D1_5 Battery Voltage (B+) Hot at all times. D1_2 Battery Voltage (B+) Hot with KEY in RUN or CRANK position. D1_6 Battery Voltage (B+) Hot with KEY in RUN position (only 2-3 seconds). This ones tricky, because of time limited. Hope you can do these voltage measurements by yourself. Forgot to mention, use battery negative terminal as DVOM ground.

So engine will START and RUN when fuel is added until added fuel is gone?

Does the starter engage and turn the engine over when the IGN SW is in the CRANK position?