Good news is the alternator itself is fine since it charges at 14V once backfed. Alldodge is right about peeling back that insulation — on these Volvo harnesses the wires splice inside heat shrink or loom tape and those splices corrode over time.
I'd bet theres a corroded splice or broken...
Following along on this one. Interesting that both motors are reading similar fuel pressure now (SB 42/49, Port similar). The spec range for the 250 Verado is 42-44 psi at idle and 49-54 key ON — so your actually right at the bottom end on both which makes me wonder if the issue is upstream of...
Alldodge's wiring diagram is spot on — on the GLP-D the fuel pump is electric and gets its power routed through the alternator circuit via that diode. So yes, a dead alternator can absolutely kill your fuel pump even if the battery is fully charged. Its a wierd design choice but thats how Volvo...
Good fix! Lapping the flywheel taper is one of those things nobody thinks about but makes a huge diffrence. The rust buildup on the ring magnet was probaly causing the flywheel to sit slightly high on the crankshaft which shifts the trigger position relative to the sensor — thats why the timing...
The seal flange goes toward the thermostat housing (facing outward/away from the block). The flat side seats against the thermostat itself. Think of it as the flange creating a lip that the housing presses down onto to make the seal.
Also regarding your earlier question about water flow...
