Fuel Pump Circuit
- Fuel pump operation is satisfactory if the following conditions are met: operating pressure is 35-45 psi (2.5-3.0 kg/cm2 ), fuel flow is at least 7.5 ounces in 10 seconds and fuel pressure remains at a minimum of 30 psi (2.1 kg/cm2 ) immediately after deactivation. If all conditions are met, check for engine or electrical problems.
- Turn ignition to "RUN" position with engine off. Connect negative lead of a digital volt/ohm meter (DVOM) to good chassis ground. Connect positive lead of DVOM to each of the following circuits to completely check fuel pump circuit. If an open fusible link is located, repair short or ground in circuit before replacing fusible link.
- Circuit 361 (Red wire) at fuel pump relay - If reading is less than 10.5 volts, recharge or replace battery. If reading is greater than 10.5 volts, circuit is okay. Continue test.
- Circuit 37 (Yellow wire) at fuel pump relay - If reading is less than 10.5 volts, locate and repair open between fuel pump relay and vehicle battery positive post. If reading is greater than 10.5 volts, circuit is okay. Continue test.
- Circuit 97 (Tan wire with Light Green dot) at fuel pump relay Insert positive lead and crank engine. If reading is less than 10.5 volts, replace fuel pump relay. If reading is greater than 10.5 volts, circuit is okay. Continue test.
- Circuit 787 (Pink wire with Black hash mark) at fuel pump relay - Insert positive lead and crank engine. If reading is less than 10.5 volts, replace fuel pump relay. If reading is greater than 10.5 volts, circuit is okay. Continue test.
- Locate inertia switch. Perform test at both terminals during engine cranking. If reading is less than 10.5 volts at one terminal, replace inertia switch. If reading is less than 10.5 volts at both terminals, locate and repair open between inertia switch and fuel pump relay. If reading is greater than 10.5 volts, inertia switch is okay. Continue test.
- Circuit 787 (Pink wire with Black hash mark) at fuel pump - Insert lead and crank engine. If reading is less than 10.5 volts, locate and repair open between inertia switch and fuel pump. If reading is greater than 10.5 volts, circuit is okay. Continue test.
- Circuit 57 (Black wire) at fuel pump - Insert lead and crank engine. If reading is greater than one volt, locate and repair fuel pump ground circuit. If reading is less than 1 volt, service or repair fuel pump.