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2001 kia sephia fuel pump does not power up in the key on position
While trouble shooting a misfire problem I have found that the fuel pump does not power up when the key is in the on position as it should. Confirmed no pressure in fuel rail. However the car starts and runs and when engine is running there is low normal pressure of 46 psi. Anyone know why the fuel pump runs when the engine is running but not in the "key on" position only?
That vehicle has a common safety feature. The ECM controls the fuel pump and will cycle the pump on once during key on. If the ECM doesn't see oil pressure, it disables the fuel pump.
Fuel pressure spec at idle is 47-48 psi, so allowing for meter accuracy, your pump is good.
Depending on mileage, there are many things to be eliminated in the secondary ignition that are more likely to cause misfire: plugs, plug wires, cap and rotor, even a weak coil can cause misfiring conditions.
thanks for the info. Still in the dark as to why the pump will not power up during key on position. if this is an indication of a fuel pump problem then I may have low pressure under load. This evening when I turned off the engine I heard a hum or vibration coming from the tank like the pump was possibly shorted and getting power when the key was off. It was not the normal fuel pump sound. I turned the ignition back to the on position and the hum stopped. I have switched coil packs with no change in my error message and the wires were replaced last year and do not show arcing in the dark. I can't understand why the pump won't power up when key is on, it is suppose to do so and it has zero pressure unless the engine is running. My errors are misfire on #2 and #3 and multiple random misfires. Switching coils gave no change in error message. vacuum check normal All injectors are clicking. Drivability feels like fuel. If you ask for easy throttle the misfires are minimized. Fuel filter changed with no change. I hate to buy parts on a guess, and I know something is not right with that pump. thanks for your thoughts...
Based upon the first part of this PM, I'd say you have a faulty fuel pump. It should not drop to zero PSI except after very long time sitting. And a good fuel pump is normally very quiet. Replace the fuel pump and it's relay.
Secondly, cylinders 2 and 3 are paired. Replace the ECM.
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