Quote:
Originally Posted by bellaCuba
Fuel pump in tank is instant shutoff.
Let us know what you find.... very curious!
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Actually, the fuel pump is not an instant shut-off. The auxiliary oil pressure switch supplies power to the fuel pump regardless of the PCM, fuel pump relay, or ignition switch, and continues to do so until pressure at the switch drops below 4 PSIG.
This symptom is not really that uncommon. It becomes a real problem if the oil pressure switch has sludge in its ports and takes minutes to turn off instead of the usual 2-5 seconds. The diagnosis can either be performed with a fuel pressure gauge connected to the fuel rail or by disconnecting the electrical connector at the oil pressure switch. As mentioned before, removing the fuel pump relay is useless since the oil pressure switch bypasses that as well.
If you discover the pressure switch is sticking, remove and clean it or replace it, then stop using oils with excessive polymers such as conventional Quaker State / Pennnzoil.