Car: 1997 Subaru Legacy GT; 2.5L H-4; electronic AWD; 4-speed automatic; 212K miles
Car details: Motor rebuilt around 173K. Assuming original injectors & fuel system still. Full 30K tuneup done @ dealership at 205K miles: PCV, fuel filter, air filter, thermostat, plugs & wires, tranny fluid change, coolant flush/change, brake fluid change, tire rotate/balance. New struts, brakes, brake hoses, brake pads, front CV axles, throttle position sensor, front O2 sensor around 205-206K miles.
Symptoms: Over time, fuel economy has worsened. At first with all city driving, achieved a max of 21 MPG. Over time this has degraded to 18MPG or worse. Also noticed that after filling up gas tank, acceleration seemed markedly improved compared to low tank. Over time, appears vacuum leak has developed. Rough, semi-erratic idle; high-pitched whistling noise coming engine bay when >3K RPM's with moderate or greater throttle; noted loss of engine power above 3K RPM's.
Note 1: Since I received the car around 200K miles, I have noted that at every gas station the pump will stop fuel delivery as if the tank is full - but it is not. Some pumps seem better/worse than others, but every fillup I can recall I have to re-start the fuel flow multiple times during the fillup. I don't know enough about the fuel evaporator neck/hose & a gas pump to figure what this issue could be, but thought it to be pertinent to the issue.
Note 2: Not long after receiving the car, I attempted to remove the throttle body to see if there was any carbon buildup. Unfortunately the coolant hoses running through it are glued on and I could not remove them - so I just re-attached the throttle body without replacing the gasket. This could be the source of the vacuum leak, yes? I will be diagnosing that soon.
I've been figuring for a while that I had a fuel delivery problem. Between what should be original injectors and a possibly failing fuel pump (re: poor engine power on low tank), I figured that was part of my acceleration & poor fuel economy issues. But just thinking a moment ago, I wonder if there is some issue with the evaporator neck in the fuel tank that could be causing fuel pressure or other fuel delivery issues? Again I don't know how that systems works, so I figured I'd throw it out here and see what the collective genius thinks.
Given I've replaced most every other component that could effect engine performance/economy (plugs, wires, front O2, PCV, etc), I'm narrowing it down to fuel delivery. Am I missing anything?
Car details: Motor rebuilt around 173K. Assuming original injectors & fuel system still. Full 30K tuneup done @ dealership at 205K miles: PCV, fuel filter, air filter, thermostat, plugs & wires, tranny fluid change, coolant flush/change, brake fluid change, tire rotate/balance. New struts, brakes, brake hoses, brake pads, front CV axles, throttle position sensor, front O2 sensor around 205-206K miles.
Symptoms: Over time, fuel economy has worsened. At first with all city driving, achieved a max of 21 MPG. Over time this has degraded to 18MPG or worse. Also noticed that after filling up gas tank, acceleration seemed markedly improved compared to low tank. Over time, appears vacuum leak has developed. Rough, semi-erratic idle; high-pitched whistling noise coming engine bay when >3K RPM's with moderate or greater throttle; noted loss of engine power above 3K RPM's.
Note 1: Since I received the car around 200K miles, I have noted that at every gas station the pump will stop fuel delivery as if the tank is full - but it is not. Some pumps seem better/worse than others, but every fillup I can recall I have to re-start the fuel flow multiple times during the fillup. I don't know enough about the fuel evaporator neck/hose & a gas pump to figure what this issue could be, but thought it to be pertinent to the issue.
Note 2: Not long after receiving the car, I attempted to remove the throttle body to see if there was any carbon buildup. Unfortunately the coolant hoses running through it are glued on and I could not remove them - so I just re-attached the throttle body without replacing the gasket. This could be the source of the vacuum leak, yes? I will be diagnosing that soon.
I've been figuring for a while that I had a fuel delivery problem. Between what should be original injectors and a possibly failing fuel pump (re: poor engine power on low tank), I figured that was part of my acceleration & poor fuel economy issues. But just thinking a moment ago, I wonder if there is some issue with the evaporator neck in the fuel tank that could be causing fuel pressure or other fuel delivery issues? Again I don't know how that systems works, so I figured I'd throw it out here and see what the collective genius thinks.
Given I've replaced most every other component that could effect engine performance/economy (plugs, wires, front O2, PCV, etc), I'm narrowing it down to fuel delivery. Am I missing anything?
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