1991 Cadillac Deville sedan runs rough, intermittent stall, low fuel pressure

Asked by Derek Jul 09, 2019 at 08:33 AM about the 1991 Cadillac DeVille Sedan FWD

Question type: Maintenance & Repair

Fuel Pressure very low. (10-15 psi) Replaced fuel pump and
filter but no change. I swear fuel pressure 20-25 psi before I
changed pump. What else would cause pressure to be so
low when checked from fuel rail? Any other tests to track it
down without throwing parts on it? All fuel lines look great.

The CHECK ENGINE and SERVICE ENGINE lights come on.
Its not throwing codes besides an F32 from the onboard
diagnostics. Are there hidden codes that can only be read
with OBD?

The cooling fans kick on with key turn no matter what. They
are not waiting for the temp to go on, they turn on from
start. Going to throw and engine coolant temp sensor at
that. Fuse for cooling fans looks fine, I assume relay is
good. Should I throw at thermostat at it?

Running rough. I rodded egr tubes which seemed to help a
little, they were pretty gunked.

Vehicle starts fine everytime but when it is put in to drive on
a flat surface the vehicle does not want to move until you
give it gas. Is this odd? Reverse it will move on its own.

There seems to be decent amount of water in muffler.
Normal or have headgaskets blown? A steady stream came
out the tiny hole in muffler when I jacked it up. Mild
precipation from exhaust when running.

She's pretty clean, grabbed her from auction. only 101,000
miles.

To Do/Check/Throw Parts at:
FPR
Secondary Air Injector
TPS
IPS/motor
Crankshaft Sensor
Fuel Injectors

Would clogged Cat choke it to death? How often to Cat's
clog? If the EGR tubes are that gunked, is everything
gunked?

Do I really have to go through the plugs/wires/rotor?

Thanks in advance.

1 Answer

3,635

Don't sweat the steady stream it's just condensation. Yes it's normal. It runs rough because you most likely have a blown or old gasket. Oil is a conductor and seeks path of least resistance therefore goes straight to the plugs and interferes with compression spark. This will get your check engine light on. It's an interior issue and has nothing to do with fluids. Yes you can change out your plugs and wires and all of that if they are old. I would do this every 18 months. THEN worry about your fuel pressure and testing that. Cheap and easy parts first always. Those plugs are probably 5/8 deep socket and I would probably take a pair of 3/8 drive extensions as well 3inch and 6.

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