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Do you have 12 volts at the B+ in the diag box when jumping the FP to B+?
Also, with jumper at FP to B+, confirmed 12 VDC at blue wire to Fuel Pump at Circuit Opening Relay.
I believe this would eliminate the Circuit Opening Relay as a possible fault as it has been bypassed using the jumper.
Next is check the fuel pump?
Just to clarify you are saying that by placing a jumper wire in FP to B+ the truck will not run? You are also saying that the truck will only run in the start position?
With jumper wire at FP to B+, engine will start - albiet after an extended cranking period.
Engine will then die after only a short time of idle - 15 seconds.
If throttle is opened - even only a little - engine will die instantly.
After a few of these short run periods, engine will crank but not start.
Disconnected fuel hose at filter and placed end in a bucket.
With ignition switch in 'start' position, a full stream of fuel flows from hose into bucket.
With ignition switch in 'run' position, there is no fuel flow from hose.
Fuel flowing into your pocket as you described is normal it will only go in or of the fuel pump will only run when the key is the start position you will have no fuel pressure in the run position unless the engine is running. At this point with the FP and B+ terminals jumpered this bypasses a circuit opening relay. This sends power directly from the EFI main relay to the fuel pump. Whenever the key is in the on position. If the vehicle is losing fuel pressure or quitting you need to investigate further into the fuel pump. Ideally you need to put a fuel pressure gauge at the cold start injector and monitor the fuel pressure when it starts to quit. It should maintain at least 30 to 35 psi.