Quote:
Originally Posted by teagueAMX
Q 1
Yes, the LPFP pressurizes the line leading up to the HPFP. The LPFP, of course, is an electric pump. As soon at the ignition is system is energized "hot" the LPFP starts and pressurizes the line. As soon as the line reaches a certain pressure (around 40 - 50 psi min) it will trip a pressure relay that completes the ignition circuit and the car can start assuming everything else is in order.
A HPFP adds one more layer - it has to build up and maintain a set pressure as well. This is where the long crank times come in - it appears the computer will allow the engine to crank even though there is insufficient pressure at either the LPFP or HPFP levels.
Q 2
Can't tell you for absolute certainty, but I believe a problem in the area would trigger a ECU code and "Check Engine" warning light.
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Thank you
it does make sense now
Nice to know what makes her tick