Symptom: No Start, No Fuel.

Theory: The Fuel Pumps on these vehicles are run at different speeds depending on engine load. The pump is run at lower speed during light load conditions to keep pump noise to a minimum. When engine load goes up, the pump will be run at full speed to supply the required fuel pressure and volume. This is accomplished by using two relays and a ballast-resistor. Don’t try to use this on Bonneville and Park Avenue Ultras because those cars use a PCM controlled module.

Parts Locations:
Fuel Pump Relay….………..…….In Under-Hood Electrical Center.
Fuel Pump Speed Control Relay…In Under-Hood Electrical Center.
Fuel Pump Ballast Resistor………On Frame Rail, inside Right Side Wheel-Well.

The Test: Before doing anything else, check the F/PMP & ENG/EMIS fuses in the under-hood electrical panel to make sure they’re not blown. If the fuses are okay, we’ll go to the fuel pump ballast resistor next. The ballast resistors go bad far more often than the relays on these vehicles. You could actually save yourself some time by going there first, even though it is more difficult to get to than the relays. On most cars, you can reach the resistor connector by pulling the washer reservoir out of the way. The resistor has a 2-wire connector on it with a Light Green wire and a Gray wire. Unplug the connector and jumper the two pins together on the engine harness side, this will bypass the resistor. Attempt to start the car. If it now runs, you’re done testing, go get a new resistor. If it didn’t start, check for voltage on the wires at the resistor connector with the engine cranking. If you have voltage, the relays are functioning and your problem is either a bad fuel pump or a wiring problem between the resistor and the pump. If there was no voltage at the connector when cranking, we have to check the relays. The relays on this vehicle are plugged directly into the Under-Hood Electrical Center panel, so there are no visible wires to look at for color reference. In order to test them, you’ll have to pull the relay out and use the numbers on the bottom of the relay to identify the terminal cavities on the panel.

To test the Fuel Pump Relay, pull it out of the panel and check for battery voltage in cavities #86 & #87. There should be voltage present because you already checked the fuses in the first step, right? Using a test-light hooked to battery positive, probe cavity #85 and crank the car. The test light should light while cranking. If it doesn’t, the PCM is not triggering the relay. Diagnose the PCM using appropriate procedures. If all terminals checked out correctly, jumper cavities #30 & #87 together and see if the car will start. If it runs, the relay is defective. If it doesn’t run, we’re moving on to the Fuel Pump Speed Control Relay.

To test the Fuel Pump Speed Control Relay, pull it out of the panel and check for battery voltage in cavities #30 & #85. Since these terminals are fed by #30 of the fuel pump relay, you’ll need to do this test either with the engine cranking or leave the jumper wire in cavities #30 & #87 of the fuel pump relay from the previous step. If this tests okay, jumper cavities #30 & #87 of the fuel pump speed control relay and try to start the car. If it starts, the relay is defective. If it still wont start, there is a problem with the panel or the Gray wire between the panel and the ballast resistor connector.

The Fix: Replace parts or repair wiring as indicated by above tests. Note that since each part depends on the part mentioned in the process before it to work, it’s very important that testing be done in the order listed above.