What is the correct voltage from relay to inertia switch. I have 12+ volts into relay, and 6.4 volta to inertia swith and pump. Is that enough volts to run pump?
I doubt it. Replace that relay!
Turns out the (bad) fuel pump ground was causing the drop in voltage. I replaced the pump by jacking the diff up as high as I could, and then placing jack stands under the frame and then dropping the diff. This created plenty of room the remove the fuel sending unit. I cut the 3 wires for the gauge at unequal length and the soldered and heat shrink sealed after installing the new pump. Entire job took about 1-1 and half hours.
Search Mercury Grand Marquis Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Mercury Grand Marquis Experts