I have a 2000 Hyundai Elantra that strats when it wants to. I’ve replaced the fuel pump in April 2010, the fuel pump relay also in April, the ECM in May 2010, which seemed to fix the problem temporarily. Then in June 2010 it started again. I had a code for the camshaft position sensor, so I replaced that, to no avail. Checked all of the usual suspects and found that the fuel pump was not working. I checked power to the pump and had 12 volts, so I removed the pump and bench tested it. It worked with direct power to it. I replaced it under warrenty anyway. When I replaced the pump I went ahead and made a new ground for it hoping that was the problem, well it wasn’t, it still is doing it. I don’t know what else it is, anybody have any ideas?
If the pump doesn’t use a switched ground circuit to activate it then you need to recheck the power to the pump when it should be running. There may be a bad connection in the power lead that looks ok voltage wise without a load on it.
the switched ground comes from the ECM to activate the fuel pump relay. During cranking the relay clicks and power is available to the pump. Once the car starts it runs fine.