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ON-VEHICLE SERVICE TSB Revision MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE> 13B-1180 CAUTION To prevent damage to scan tool MB991958, always turn the is no fuel leaking from any section when the fuel pump is 6. Stop the fuel pump. Standard value: Approximately 324 kPa (95.7 in.Hg) at 9. Check to see that fuel pressure at idle does not drop even after the engine has been revved several times. 10.If any of fuel pressure measured in steps 8 to 9 is out of specification, troubleshoot and repair according to the table 11.Stop the engine and observe fuel pressure gauge reading. It is normal if the reading does not drop within two minutes. If it (1) Squeeze the fuel supply line closed to confirm leak-down occurs from defective fuel pump check valve. (2) If pressure continues to drop with both fuel lines squeezed closed, injector(s) are leaking. AC305412 AB MB991910 DATA LINK CONNECTOR MB991824 MB991827 SYMPTOM PROBABLE CAUSE REMEDY • Fuel pressure too low • Fuel pressure drops after racing Clogged fuel filter Replace fuel filter Fuel leaking to return side due to Replace fuel pressure regulator Low fuel pump delivery pressure Replace fuel pump Fuel pressure too high Binding valve in fuel pressure Replace fuel pressure regulator SYMPTOM PROBABLE CAUSE REMEDY Fuel pressure drops gradually Leaky injector Replace injector Leaky fuel regulator valve seat Replace fuel pressure regulator Fuel pressure drops sharply Check valve in fuel pump is held Replace fuel pump |