Relieving fuel pressure by disconnected inertia switch

[600$04Ranger]

Changed my fuel filter today. First time since I rebuilt the engine around 15,000 miles ago. Previous owner had deleted inertia switch and just twisted the two wires for the switch together. I haven't gotten around to finding a new switch and mostly forget that it needs one because it runs fine without it. However, I should probably get one and lessen my chances of being burned alive in an accident.

Anyways, I disconnected the wires and cranked the engine to supposedly relieve pressure before removing the old filter. Engine cranked and started a few times but sounded like it wasn't getting much fuel so I turned off the key and went ahead with the removal. Quite a bit more fuel poured our of the lines than I imagined (maybe a few cups) but finally stopped. After new filter went in I reconnected inertia switch and it started right up. Ran great as usual. Does anyone know if it's normal for the engine to start after the inertia switch wires are disconnected or do I need to be aware of some future or current issue with fuel system? Anyone have a similar experience changing fuel filter?

 

[Dirtman]

Disconnecting the inertia switch only disables the fuel pump, there is still residual pressure in the system so the engine can still start and run for a short period. The easier way to relieve the pressure on the system is to simply press the Schrader valve on the fuel rail (put a rag over it and press the pin with a screw driver or pick). And fuel will always come out when changing the filter. The lines, rail, dampener, and filter itself all hold a bunch of fuel plus there is a bit of a siphon effect since the fuel filter is below the fuel level in the tank. Nothing you can do will stop fuel from spilling out when you disconnect the filter, you just want to relieve the pressure so it doesn't spray out at 65psi...

 

[600$04Ranger]

Thanks Dirtman! That's what I figured. Except my fuel rail doesn't have the Schrader valve. It has a metal quick connection that I probably could use to clear some of the fuel and also relieve some of that siphoning effect you mentioned. Then probably should have captured whatever else came out of the 3 lines connected to the filter in a container instead of wasting it. Especially with $4 gallon gas prices these days

 

[pjtoledo]

the engine will stall when the fuel pressure gets down to 15-20 psi.
which means there will still be 15-20 psi of fuel pressure in the lines after it runs out of fuel.