Re: reverse polarity
Think he is talking about fuel pressure in the rail. Bad valve in the fuel filter will cause pressure to leak down quickly. There is a shraeder valve on the passenger side front of the engine visible when you remove the engine cover.
The pressure spec is about 50 psi. On mine it came up very quickly and when I turned the key off it stayed up for a half hour.
BTW I never had a HF fuel pressure gauge that would hold pressure so spent a bit more for one from Sears with a drain tube.
Just one more test to make. Must admit I still do not understand exactly what the car is doing wrong. Thought it want cranking, then it was running badly.