Only 3 volts at fuel pump

gasoline
pump
mercury

#1

I have a 98 Grand Marquis that is not pumping fuel. I checked the voltage at the inertia switch and only had 6 VDC. Underneath the trunk I checked the voltage at another connector and only got 3 VDC. Do you think I have a bad ground?


#2

Check the fuel pump fuse. This is fuse 1, 20 amp, located in the under hood fuse box on the right front of the engine compartment.

Tester


#3

Do you think I have a bad ground?

Why guess? You have a voltmeter, measure the voltage drop from the fuel pump “ground” to the chassis “ground” and you’ll know.


#4

I assume that the voltage readings you stated were made using a good ground reference point. I also assume that the devices you tested are on the power lead side of the load. If that is correct then the trouble isn’t a bad ground but rather a bad connection to power. The fuel pump relay is a likely culprit. It would be nice to know where the 3 volt measurement was taken since the voltage is less than the first reading. If the 3 volt reading is after the load on the ground return side then there is a grounding problem also. A good ground point will be at zero volts when compared to a good ground reference point.