Saturn Repair Problems? Ask a Mechanic for Answers ASAP
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Does the engine actually feel like it is running rough with this issue here?
O.k.,the code P0420 indicates the catalytic converter is operating incorrectly.If the catalytic converter is restricted it will cause excessive back pressure which leads to the P0300 fault code as well as rough engine running.I have had to replace several catalytic converters in the past before for this fault here.I would have the exhaust back pressure tested with a back pressure tester.This is done by threading the tester into the pre catalytic converter oxygen sensor port then running the engine from idle to wide open throttle to see if the back pressure exceeds 1.5 psi.If it exceeds this back pressure at any rpm then the catalytic converter needs replaced to correct this here.You can usually rent this tool from a parts store most of the time.I suspect this is the cause here needing replaced.
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O.k,did the misfire and rough running occur after the cat was cut off as well as the P0420 code?
O.k.,the code P0420 will not clear until you put on a cat. that is compatible with this model here and make sure you have no exhaust damage or leaks.It will stay on until this is done.It was most likely on before due to the old cat. incorrectly operating.Is your actual fuel rail pressure 85 psi with the key on or engine running?
Is this an accurate fuel pressure test gauge?
Your fuel pressure should only be between 50 and 60 psi with the key on.If it is actually higher then this will cause running issues like this here and is caused by either a faulty fuel pump creating to much pressure needing replaced or fuel pressure regulator at the fuel pump needing replaced.I have seen high pressure cause misfires and rough running like this here and usually it is the fuel pump itself needing replaced.
With the engine running you should only see around 52 to 55 psi for pressure.
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My info doesnt show a picture of this regulator but it does tell me it attaches to the fuel return pipe on the fuel pump module itself.If this is stuck closed not allowing pressure back to the tank this causes high pressure and running issues like you have here.
It does appear to be in the tank itself or on top of it on top of the fuel pump module assembly but it is located in line with the return line.I show a cost of $47 for this pressure regulator from a dealer.It may be cheaper at a local parts store.
Here is the part number
For a cost of $47.36 from most dealers.
It looks like it is attached to the fuel pump.You actually replace it when the pump was replaced.
Did you have the high fuel pressure reading with the old and the new pump?
That is actually for fuel tank pressure and isnt the pressure regaulator.My info shows that the this model uses a fuel pressure regulator but looks like it is part of the pump assembly after doing more research on it.
Is there any way you can get the pressure re tested with a different fuel pressure test gauge at all as this pressure reading is still to high if this is PSI pressure?
With the pressure this high and the pump replaced (which came equipped with the pressure regulator) and the pressure still high the only other thing I can think of is a restricted or damaged fuel return line.I would check the fuel return lines for any issues.
Can you verify the year of this model as well as engine liter size?
Did your fuel pump module have two fuel lines at it
Here is what your fuel pump consists of:
FUEL PUMP MODULE
The fuel pump module consists of the following major components:
- The fuel level sensor
- The fuel tank pressure (FTP) sensor
- The fuel pump
- The fuel pressure regulator
Here is how it operates:
The fuel pump is mounted in the fuel pump module reservoir. The fuel pump is an electric high-pressure pump. Fuel is pumped to the fuel injection system at a specified flow and pressure. Excess fuel returns to the fuel tank through the fuel return pipe. The fuel pump delivers a constant flow of fuel to the engine even during low fuel conditions and aggressive vehicle maneuvers. The control module controls the electric fuel pump operation through fuel pump relay. The fuel pump flex pipe acts to dampen the fuel pulses and noise generated by the fuel pump.
It is a fairly simple diagnosis for high fuel pressure as seen here.
According to that diagnostic chart on your model here your fuel pressure is above 60 psi and this leads to replacing the fuel pump module.It may be that the new replacement is faulty needing replaced again under parts warranty.
I apologize for the delay as I had to run out yesterday and couldnt get back here.I dont see any rating left yet.
According to the diagnostic flow chart above the high fuel pressure leads to the fuel pump again.As long as you have no damaged fuel lines the fuel pump is creating to much fuel pressure needing replaced again.This is causing the running issues here.