2001 Lincoln Town Car 4.6 no fuel pressure.

2001 Lincoln Town Car with no fuel pressure. Codes P0231(fuel pump secondary circuit low) and P0232 (fuel pump secondary circuit high). Check fuel pump relay. It checked out ok. Checked the inertia switch with a Ohm check it has continuity and checked out fine. Took my power probe and applied voltage to the pump at inertia switch wire PNK/BLK and the pump worked. I got pressure at the fuel rail on my pressure gage. Fuel pump worked with 12 volts from the power probe. Checked the DG/ YE wire at the inertia switch connector with DVM and had 7.1 volts. jumped wires at inertia switch and fuel pimp still did not work. The fuel system is a mechanical Return Type system with a fuel pressure regulator on the fuel rail with a return line . Researching the problem one possibility is the fuel monitor pump circuit. What makes up the monitor circuit? any help would be appreciated.

auto58 wrote: Checked the DG/ YE wire at the inertia switch connector with DVM and had 7.1 volts.

Was this measurement taken during cranking/pump prime? Or just KOEO?

Including the wiring diagram for reference.



If your 7.1V measurement was taken with the fuel pump relay energized, then you absolutely have a voltage drop ahead of the inertia switch. Next place to test is at the Battery Junction Box. I see that you tested the relay - that's fine. I'm not concerned about the relay at this point, but the wiring itself.

I'd start with some quick checks of all four fuel pump relay pins with your DVOM. Partially install the relay in its socket so all four pins make contact, but still have some exposed pins for testing purposes.

Because of your 7.1V reading, we're mostly concerned about the load side of the relay (pins 3 and 5). One should show battery voltage if the pump is on or not. The other should show the battery voltage with the relay energized (cranking or during pump prime).

Do these tests and let us know what you find.

the voltage reading was with KOEO

the voltage reading was with KOEO. I used a relay jumper and all of the pin points on the relay were correct.