Fuel Filter location(s) 2000 Legacy.

[mtsmiths]

SEARCH won't work on my browser, so I'm asking a question I'm sure has been answered many times.

 

Our Legacy is acting like it has crud in the fuel filters, so. Where are they, not even mentioned in the owners manual.

 

Thanx all, Smitty

[frag]

This is something that has most probably not changed since 1996.

It should be found near the driver's side strut tower. It is a shiny canister a tad smaller than an oil filter. There is a spring clip holding it in place. Undo this clip and the rest is intuitive. You might need a plair of battery pliers to get the fuel hoses to move before removing them.

Most of the time the fuel system pressure goes away in a couple of hours ( I have a fuel pressure gauge) BUT I just went to my car and after two solid days parked at the same place the gauge is still registering 25+ psi. This is the absolute first time I've seen this happen. So it's most unlikely but possible.

So have a rag ready and protect your eyes. Pressure or not there is only a small amount that will spill. Take care and stay away from the Purple Jesus while your're at it .

[mtsmiths]

Merci, mon ami.

[FlyFlicker]

Lift up the cover either in the trunk or in back if you have a wagon. You will see a domed cover held on by 4 screws. Remove this cover to expose the fuel pump. Undo the electrical connection to the pump and crank the engine. This will relieve the pressure in the fuel line. After you change the filter reconnect the pump and replace cover.

[mtsmiths]

$33.51, is this a critical Subaru part (like oil filters), I can't imagine so, but one never knows (and I don't).

 

'Nother thought, according to the Owners manual alcohol additive is limited to 05%. Lotsa states here out west pump 10% gasohol. Is this a pending problem? Inquiring minds want to know.

 

It's a bother with my antique airplane, which is rated to run on MoGas, but NO alcohol.

[frag]

$33.51, is this a critical Subaru part (like oil filters), I can't imagine so, but one never knows (and I don't).

 

I dont really know the comparative quality of cheaper aftermarket fuel filters but I had a look at what Canadian Tire was selling and thought it looked so cheap compared to the OEM fuel filter. So I always replace mine with a Subaru filter. When in doubt, go with OEM.

I do that with the thermostat, PCV valve, coolant temp sensor, crank and cam sensor (dont even know if there are after market replacement for those), ball joints.

But I buy aftermarket O2 sensors (General) and air filter (Canadian Tire). For the later, I compared OEM to what C.T. was selling and I could'nt see any difference. It's garantied on the box to be equal or superior to OEM.

[mtsmiths]

Thanks all, $18.00 at NAPA (looked just like the Subaru part, except painted black) and a can of Seafoam, five minutes (no fuel spray, BTW) and all's as right as rain.

 

The best part?

 

The Pretty One has renewed confidence in my mechanical skills.

[Tiny Clark]

Still on the first filter after 123,000 miles, and going strong.

[mtsmiths]

Still on the first filter after 123,000 miles, and going strong.

 

I think the filter on my '95 at 135,000 is original. The '00 is at 165,000 ... and I suspect that the gas in western Montana may not be as clean as that in Germany. We've got some OLD in-ground tanks around here, and US regs are generally not as strict as EU.

[jib]

On a fuel injected car you really should change it on a regular interval. The pump puts a lot of gallons through that filter and injection pumps don’t like pumping against a constant head, unlike carb type electric fuel pumps.

 

 

While saving the $15 (Napa) may seem like a good thing, you may be significantly shortening the life your fuel pump instead.

FYI - I do it on a 50K schedule, unless prompted to do it sooner by a warantee.

 

jack

[mtsmiths]

 

 

While saving the $15 (Napa) may seem like a good thing, you may be significantly shortening the life your fuel pump instead.

jack

 

 

And why would that be?

[jib]

And why would that be?

 

As you start to get crud accumulating in the filter the pressure required to push the gas through the filter increases. While the gas station tanks are much better these days, there is still a certain amount of crud in their tanks and eventually in yours. Over time this will build and slowly start making the pump work harder to maintain the pressure through the filter. You may see it as a bit of loss of perormance, you may not, but over time a filter will clog. Unlike a carb, most fuel injection systems pump the gas through a regulator and back to the tank, so the pump cycles the gas constantly. When that filter gets to be a restriction, the pump suffers and has to work increasingly harder.

 

Do you wait until your air or oil filters are affecting performance to change them?

 

Just this week one of my co-workers was complaining that her car was sluggish and she brought it into the shop. She had done regular tuneups, etc., but had not touched the fuel filter. After 105k miles, it was pretty clogged and a simple filter change restored the cars performance.

 

The Subie fuel filter is tiny compared to many european cars and should be changed on a regular interval. It's preventative maintainence.

 

Jack

[mtsmiths]

I'm not questioning the value of CHANGING the filter, I'm questioning the apparant claim of superiority of an OEM fuel filter when looking at a service life of 30 to 50K miles.

 

Some parts (i.e. oil filter, T-belts ... no question, but a gas strainer?)

[jib]

You're "preaching to the choir" here. I typically don't use OEM parts, because I've found the aftermaket to be either similar quality at a lower price or better quality at the same or lower price. Just do your research first. Simple things like using an inferior (Fram) oil filter instead of say a Wix/Purolator/etc., could be far worse over the long haul than paying a few extra dollars for the OEM filters.

 

Jack

[sparkster58]

ok...over a month ago i bought a 93' leg with 221k...i know have over 225k..since my arizona trip..on one time did it stall...not sure if that was the fuel pump...but when i bought it ...the stalling was every other day until i started putting FI cleaner in the gas...that worked about 95%....iam still thinking of getting a new fuel filter asap. tho.... Spark

[friendly_jacek]

As you start to get crud accumulating in the filter the pressure required to push the gas through the filter increases. While the gas station tanks are much better these days, there is still a certain amount of crud in their tanks and eventually in yours. Over time this will build and slowly start making the pump work harder to maintain the pressure through the filter. You may see it as a bit of loss of perormance, you may not, but over time a filter will clog. Unlike a carb, most fuel injection systems pump the gas through a regulator and back to the tank, so the pump cycles the gas constantly. When that filter gets to be a restriction, the pump suffers and has to work increasingly harder.

 

Do you wait until your air or oil filters are affecting performance to change them?

 

Just this week one of my co-workers was complaining that her car was sluggish and she brought it into the shop. She had done regular tuneups, etc., but had not touched the fuel filter. After 105k miles, it was pretty clogged and a simple filter change restored the cars performance.

 

The Subie fuel filter is tiny compared to many european cars and should be changed on a regular interval. It's preventative maintainence.

 

Jack

 

You explanation intuitively makes sense, but is not entirely correct.

Fuel pump does not neccesarily work much harder with a moderately dirty filter. It works equally hard all the time pumping high volume under pressure higher than the fuel pressure at the injectors. With clean filters, pressure regulator relieves the exccessive pressure and bypasses a significant flow back to the tank. At this point, the pump works hard because of the high flow condition. As the filter is clogged more, the pressure at the pump may increase some, but the flow decreases a lot as the pressure regulator will bypass less gas to the tank.

Obviously, when filter is tottaly cloged, the pressure regulator may not be able to compensate for the lost pressure and the pressure at the injectors will drop. This can potentially stress the pump a little bit. Sadly, most ECU do not monitor the fuel pressure, so filters should be changed regularly.

[jib]

I agree 100%, but didn't make myself clear. The regulator is the big pressure drop, until the filter becomes a problem. Taking some of the pressure drop, hence reducing the flow across a very dirty filter, could lead to fuel starvation during high fuel demand situations.

 

Jack

[frag]

You explanation intuitively makes sense, but is not entirely correct.

Fuel pump does not neccesarily work much harder with a moderately dirty filter. (1)It works equally hard all the time pumping high volume under pressure higher than the fuel pressure at the injectors. With clean filters, pressure regulator relieves the exccessive pressure and bypasses a significant flow back to the tank. (2) At this point, the pump works hard because of the high flow condition. (3) As the filter is clogged more, the pressure at the pump may increase some, but the flow decreases a lot as the pressure regulator will bypass less gas to the tank.

Obviously, when filter is tottaly cloged, the pressure regulator may not be able to compensate for the lost pressure and the pressure at the injectors will drop. This can potentially stress the pump a little bit. Sadly, most ECU do not monitor the fuel pressure, so filters should be changed regularly.

 

I've underlined and numbered three passages in your post.

I'm no fuel pump expert, but I have some doubts about each of these statements.

(1) The pump is not "pumping high volume under pressure higher than the fuel pressure at the injectors." If the fuel pressure regularor is set at let's say 30 psi, the fuel pressure at the pump will be no higher than 30 psi. The pump on my car is capable of 60-65 psi but this pressure is present at the pump only if I pinch the fuel line downstream from the pump. For the same reason a moderately dirty filter will increase the pressure at the pump while maintaining a constant pressure at the injectors (if the regulator is good).

(2) At 30-40 psi, a pump able to produce 60-65 psi is working easy, is freely spinning and not working hard exactly like an engine that is permitted to rev.

(3) The condition you describe here is like logging an engine (high load at low revs) and we know that this is the worst condition for an engine. I think it is the same for a fuel pump.

For these reasons, I think that a dirty filter, by increasing the pressure at the pump, by creating a condition where the pump strains at lower revs, will make it run harder and hotter and shorten its life.

For the sake of argument.

[cookie]

I have run a prefilter in the past. You have to make sure the filter you use is able to handle your current line pressure. One then plumbs it into an easily accessible location.

This is somewhat common in some areas of the third workd.

[friendly_jacek]

I've underlined and numbered three passages in your post.

I'm no fuel pump expert, but I have some doubts about each of these statements.

(1) The pump is not "pumping high volume under pressure higher than the fuel pressure at the injectors." If the fuel pressure regularor is set at let's say 30 psi, the fuel pressure at the pump will be no higher than 30 psi. The pump on my car is capable of 60-65 psi but this pressure is present at the pump only if I pinch the fuel line downstream from the pump. For the same reason a moderately dirty filter will increase the pressure at the pump while maintaining a constant pressure at the injectors (if the regulator is good).

(2) At 30-40 psi, a pump able to produce 60-65 psi is working easy, is freely spinning and not working hard exactly like an engine that is permitted to rev.

(3) The condition you describe here is like logging an engine (high load at low revs) and we know that this is the worst condition for an engine. I think it is the same for a fuel pump.

For these reasons, I think that a dirty filter, by increasing the pressure at the pump, by creating a condition where the pump strains at lower revs, will make it run harder and hotter and shorten its life.

For the sake of argument.

 

Go ahead, put dirty a filter in and measure the fuel pump temp. If it is hotter, I will believe you.

Wait, you can also measure the current draw at the pump, that will save you the temp measurment.

Either way, please post back with numbers.

 

I hope it is clear by now where the filter is located (you know, for the the original poster :-)

[frag]

Go ahead, put dirty a filter in and measure the fuel pump temp. If it is hotter, I will believe you.

Wait, you can also measure the current draw at the pump, that will save you the temp measurment.

Either way, please post back with numbers.

 

I hope it is clear by now where the filter is located (you know, for the the original poster :-)

 

f. j. you're asking more of me than you gave yourself in your post. Why should I be the one to bear the complete burden of the proof ? Aint just!

If I can simplify my argument : it seems evident that a pump working against higher pressure will be prone to wear faster than one working against lower pressure. The only questions as far as I'm concerned are (1) "what quantity of dirt in the filter will cause a restriction sufficient to raise the pressure between the pump and filter - and make the pump work harder - and (2) how much should the pressure be raised at the pump to shorten its life by a significant margin."

I will perhaps be able to partly answer the first question in the future. I already have a fuel pressure gauge in the line going from the filter to the fuel rail and regulator. I will try to find another gauge of the same type and install it between the filter and pump and then will be able to compare the two pressures. The small VDO gauge being not very expensive (only problem will be to find another one), if it can save me one fuel filter replacement, it will have practicaly paid for itself. The rule will be : the fuel filter will need replacing ONLY when the upstream (of the filter) pressure will be higher than the downstream pressure.

As for the real world effect on the pump's longevity, I'm afraid that will remain a matter for speculation.

Take care.

[jib]

We are regressing into nonsense.

 

1. Over time filters (air, oil and fuel) will clog.

2. If the get dirty enough, you're working your system harder or running it inefficiently.

3. Fuel pumps are a lot more expensive and labor intensive to change than filter.

 

Please draw you own conclusions.

 

Jack

[frag]

We are regressing into nonsense.

 

1. Over time filters (air, oil and fuel) will clog.

2. If the get dirty enough, you're working your system harder or running it inefficiently.

3. Fuel pumps are a lot more expensive and labor intensive to change than filter.

 

Please draw you own conclusions.

 

Jack

 

If this is an answer to my post(s), read again.

[avk]

I believe that, unless the filter is seriously clogged, the actual "botlleneck" which determines the load on the pump is the pressure regulator, except maybe at very high RPM.

[jib]

If this is an answer to my post(s), read again.

 

Nope, I agree with you, but i'd rather replace a $15 part every 50k or so than take the time and effort to monitor the fuel pressures up and down stream of the filter.

 

OTOH - in my home I have a magnehelic differential pressure gage across the furnace filter so I know when to replace the $20 filter element.

 

Jack