Car Repair World

Low Fuel Economy  Today’s engine management systems rely on many different sensor inputs to regulate fuel economy, performance and emissions. Symptom: Poor Fuel Economy Probable Causes: Fuel Rich Codes (P0172 and/or P0175) Coolant Sensor (P0115 to P0119) Misfire Codes (P030x) Mass Air Flow (P0100 to P0105) Oxygen Sensor Codes (P0130 to P0167) or (P0036 to P0064) MAP Sensor (P0105 to P0109) With the price of gasoline, you don’t want to ignore this kind of problem for long. When fuel economy is down, you may find any number of codes: P0172 and/or P0175  are rich codes, and indicate a general rich air/fuel condition. The underlying cause may be anything that increases fuel delivery, such as excessive fuel pressure, a defective fuel pressure regulator, plugged return line, or leaky injectors. Decreased airflow from a dirty air filter or restricted air intake misleads the mass airflow sensor or engine management system into believing the engine is usin...

How To Test Vehicle Fuel Pump And Fuel Pressure Regulator Helpful Information Some vehicles are not designed with a fuel pressure test port, in which case a fuel filter adapter must be used for the gauge connection. A fuel pressure regulator is controlled by a diaphragm and spring combination in conjunction with intake manifold vacuum. When a fuel pressure regulator diaphragm ruptures, it allows raw fuel to enter the vacuum feed line and into the engine. This condition creates a rich  black smoke  from the tail pipe on start up and while running. Remove the vacuum line from the regulator, if fuel is present, the regulator has failed. Some GM (CPI Injection) are designed with an internal regulator in which the intake manifold must be removed to access. Most fuel pressure regulators are on the top of the fuel rail. If you cannot locate the fuel pressure regulator consult a  repair manual . Tool and Supplies Needed Fuel pressure gauge kit Protective eyewe...