Q: I have some questions regarding the fuel pump on my 1995 Mercury Cougar with the 4.6-liter V-8. The car was garaged for about three months and now won't run. It will start and run for a few seconds on starter fluid, so it appears to have spark. When the key is turned to the "On" position I do not hear a "whirring" sound from the fuel pump. I checked the fuel pump fuse in the power distribution box and it showed continuity. The manual then said to check the inertia switch terminals for continuity. Do I just unplug the connection and use a continuity tester or an ohmmeter on the inertia switch? Does it just pull apart or is it screwed together?
If the inertia switch is OK, the manual then says to run a jumper wire from the "FP" terminal on the data link connector (DLC) or the diagnostic test connector (DTC) to ground. If the pump runs, it means that the PCM is probably bad as this process bypasses the PCM. The problem is that I cannot find the DTC/DLC on my car.
Lastly, the manual says to unplug the fuel pump connection near the front of the tank and check for power. If there's power, then the pump is likely bad. If there's no voltage, then a relay may be bad, but the manual states that checking the relay on a 1994 and later car is not a DIY project. Does this sound like a reasonable approach or do you have a better DIY troubleshooting plan?
A: Remember the "KISS" principle? Try the simple stuff first. First check the inertia switch for the fuel pump, located behind the trim panel on the driver's side in the trunk. If the vehicle suffers a big bump or hit as could happen in a crash, this magnetic switch will open the electrical connection to stop the fuel pump. To reset the switch, just push the reset button downward. You can test the switch by unscrewing it from its mount, unplugging the connector and test the connections for continuity.
If that's not the problem, with the car in park and foot on the brake have a helper try to start the car while you pound on the bottom of the fuel tank with a rubber mallet. "Tired" fuel pumps will often start with a little "outside" help. If this works, the fuel pump itself is the likely problem. Since the fuel pressure should be 30 to 40 psi with the engine running, an amperage "draw" test should show 3 to 4 amps — roughly one amp per 10 pounds of fuel pressure.
If this doesn't start the pump, try the jumper trick at the DLC, which is located behind the instrument panel below the glove box.
If these simple tests don't provide an answer, a scan tool might. DTC fault codes P0230/P231/P232 identify specific problems with the fuel pump circuitry and voltage.
Q: My daughter has a 2005 Subaru Legacy wagon with about 100,000 miles. The headlights burn out about every six months and the dealer cannot find the problem. They say all the electrical checks out. Help!
