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Raw fuel found in intake manifold and some vacuum lines - advice?
1999 Mercury Mystique

Raw fuel found in intake manifold and some vacuum lines - Advice?

(1999 Mercury Mystique)
Hi all,
We own a 1999 Mercury Mystique, 2.5L V6, 24 Valve DOHC.

Recently the car broke down and we're working through fixing some issues it's having, and we'd appreciate some advice on something we found. While looking at the intake manifold, we noticed raw, liquid fuel poor out of a tube on the driver side, closer to the firewall (top right of picture below), and similarly in some vacuum tubes.

A potentially related symptom we found is while replacing the exhaust O2 sensor, there was what we would call an excessive/heavy amount of carbon build up on the sensor.

Manifold: http://bldouglas.com/etc/car/1.jpg
Vacuum lines: http://bldouglas.com/etc/car/2.jpg

We have a home OBDII reader, and the car currently has these codes:
P0155 - O2 Sensor Heater Circuit
P0156 - O2 Sensor Circuit
P0401 - Exhaust Gas Recirculation Flow Insufficient Detected
P1520
P0171 - System Too Lean
P0302 - Cylinder 2 Misfire Detected
P0301 - Cylinder 1 Misfire Detected
P0161 - O2 Sensor Heater Circuit
P0174 - System Too Lean
P0303 - Cylinder 3 Misfire Detected

Any and all advice on what may be causing this or other issues and a starting place would be much appreciated! Thanks in advance!
1 answer & 0 comments
Popular Answer
on May 06, 2014
Most likely suspect is the fuel pressure regulator....google image.
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Vacuum Leak Diagnosis
$88 - $111 Learn More
on May 06, 2014
Most likely suspect is the fuel pressure regulator....google image.
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