After replacing the fuel pump relay oil pressure sending unit and distributor how can you tell if the ECM on your 1988 suburban is preventing the fuel pump relay from turning the fuel pump on?
I am tackling the same thing on a 1994 Ford Arerostar van. I
think that the wire from the fuel pump relay is also connected to
the Powertrain Control Module. ( The book makes mention that that
the PCM controls the fuel pump! ) If this is true then the PCM may
place a "LOW" on that line if it wants the pump off, preventing the
relay to pass the voltage to the initeria switch and then the
pump??? ( I'll let you know...you let me know? )