FuelPump Relay Issues. Another potential cause for bad fuel pump symptoms is a faulty fuel pump relay. This relay controls the power supply to your Tacoma's fuel pump, and a faulty relay may lead to: Intermittent power loss to the fuel pump; Inability to start your truck; Unpredictable pump operation, leading to stalling or rough running Howto test a fuel pump relay. Engine Performance Diagnostics chapter 16 pages 9-16Symptoms - fuel pump fuse keeps blowing - intermittent no start - inter Surelya brand new fuel pump can at least give me some noticeable performance over the 200k mile fuel pump! I went back under and checked the wiring to the pump to make sure it wasn't getting hot and no problems found. To sum it up: Old 200k mile fuel pump - relay gets really hot New fuel pump - relay still gets hot No noticeable performance gained Dependingon year, make, and model, DTC P0231 may have number of causes. Here are some of the most common. Relay - If the fuel pump relay is faulty, no voltage will go to the fuel pump or monitor. Harness Damage - If there is damage to the harness going to the fuel pump, it can cause excessive resistance (corrosion), an open circuit (broken Voltageat pump power terminal must be within .5v of battery power when relay is turned on with amp meter at pin 22. Check power from battery if voltage is low. Check the inertia switch and fuse if battery voltage is missing. Pin 22- (light blue-orange) Grounded to turn "on". Voltage will drop to about 1v when "on". WWzd.

when a fuel pump relay is bad