Good morning everyone. I have a 2004 Suburban. 5.3l. I recently replaced upper manifold gasket. All connections appear good. New knock sensors, new oil pressure sender. Cleaned injectors, tested to see if they ran well. Put everything together, started her up and boom....hard start. Took 3 cranks to start. Primed fuel pump, started right up. Tested fuel pressure...read 36psi. No drop in pressure after a few hours. Replaced fuel pump ( integrated fuel pressure regulator and filter). Started up...hard start...one crank only this time. Baffled. Checked fuel pressure again...46psi. Not as low as before but still low. Thinking bad ground or defective pump. Thoughts.... it's a Delphi pump
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