Engine sputter at high RPM?

[kenithzs]

After about 15 minutes of hard driving at high RPM's, my '00 2.5RS will stall out at around 4500 RPM. It will then run as normal for a few minutes and then sputter out to the point where I cannot get it over 1500 RPM. Once the problem starts it snowballs until the car barely runs, Then I'll let it sit for about 5 minutes and it will run fine for five minutes and then sputter down to low RPM. The next day it will run strong for 15 minutes and then repeat. I pulled the code with the scantool program and it gave me P0463- Fuel Level Sensor High Input. The car was sitting still for a couple of years before I got it so I would not be surprised to find out that the sending units in the tank were hosed before this problem cropped up. If this error is the problem, could a fuel level sensor wreck things this badly?
Assuming that the error code was pre-existing, could these be the symptoms of a fuel pump/relay gone bad? I was thinking that perhaps it is extremly filthy injectors, but then again, why would it only occur after the car gets warmed up?



Thanks, any advice or info would be great.
-Ken

[borgesxg]

Do you know what the hardest this about beeing a Subaru owner is ?

[bryan_johnson]

bump for curiosity

[Patrick L]

Have you trying to get it up over 4500 by giving it full throotle.
I have had 2 front o2's(a/f meter) go bad without a CEL. They were giving a too low of a voltage reading. It's wold shudder like it wanted to stall out but once I got the RPM's up over 4000-4500 it would excelerate fine.

[kenithzs]

Originally Posted by Top_Dog

Have you trying to get it up over 4500 by giving it full throotle.
I have had 2 front o2's(a/f meter) go bad without a CEL. They were giving a too low of a voltage reading. It's wold shudder like it wanted to stall out but once I got the RPM's up over 4000-4500 it would excelerate fine.

Yes when I give it full throttle it will not go above 1000 RPM, its almost as if the RPM govenor is kicking in about 7000 RPM's too soon.

[Bbennett]

Did this problem ever get resolved? I'm experiencing the same issue for my 2011 Impreza outback sport.

[Chosenchange]

I just rebuilt my 98 Forester. Runs great but at what seems like random times it bogs down a little and feels like I can't give it gas. No other symptoms though runs great 94 percent of the time. I can't even replicate. I do notice my low idle fluctuates after it happens then goes back to normal.

[derrick-s]

P0463 Causes:
Faulty fuel level sensor
Faulty fuel level pump
Malfunctioning fuel level sensor float
Damaged fuel tank
Frayed wiring/connection to fuel sensor harness

If the vehicle sat for a few years, I would start with checking the connector to the sensor or fuel pump (if its built into the pump). Look for bad wires possibly chewed up by rats. Follow the wiring really well. If thats fine then check the fuel pressure with a gauge. Make sure your within specs when the problem is happening (most likely above 45psi). You can rent one free from the parts stores. Does your gauge show a full tank when the tank is actually full, or 1/2 when its at 50%? Start with these things and kep it easy. You have a code, fault trace that first.
Also, does your scan tool show fuel trims? See if your running lean or rich at idle and let me know the readings.

[Bbennett]

Originally Posted by derrick-s

P0463 Causes:
Faulty fuel level sensor
Faulty fuel level pump
Malfunctioning fuel level sensor float
Damaged fuel tank
Frayed wiring/connection to fuel sensor harness

If the vehicle sat for a few years, I would start with checking the connector to the sensor or fuel pump (if its built into the pump). Look for bad wires possibly chewed up by rats. Follow the wiring really well. If thats fine then check the fuel pressure with a gauge. Make sure your within specs when the problem is happening (most likely above 45psi). You can rent one free from the parts stores. Does your gauge show a full tank when the tank is actually full, or 1/2 when its at 50%? Start with these things and kep it easy. You have a code, fault trace that first.
Also, does your scan tool show fuel trims? See if your running lean or rich at idle and let me know the readings.

We checked the wiring and it looks to be fine no frayed wired. My gas gauge is occasionally working but sometimes drops to empty then comes back. I have gotten a code p0171 for fuel bank lean once but it went away on its own. The fuel pump was tested by the mechanic that replaced the fuel tank and he said it was sitting right at 40 to 50 psi and recommended not replacing the pump itself. However when we did some driving tests we noticed the fuel pump changes from a constant buzzing to a pulsing buzz. When the pump changes to pulsing is when I have my acceleration issues. Any thought on whether it's the pump? Or maybe the pumps overheating? Maybe the ecm changing the pumps speed? Thank you in advance anything helps.