Hidden Fuel Filter

[cleverdick]

Has anyone on here ever had theirs replaced? How long should it last? Until I got the Lexus dealers' workshop manual, I thought that the external fuel filter canister was the only one. But these cars (series 1 anyhow) have a filter on the fuel pump in the tank as well. This is an issue for me, because on a previous car (not a Lexus) I had this 'secret' hidden filter clog up, cave in and block the pipe, causing my car to stall at high speed. The car had done about 100k miles. I just do not know why manufacturers put a filter in the tank that you can't get to. It's stupid design, plain and simple. You can replace the external filter as often as you like, but if you're experiencing running problems or loss of power, then it could well be the one on the fuel pump that's the problem. Especially if it's made of a very fine gauze (like the one on the Ford was). I'd certainly appreciate your comments on this.

[obergc]

The purpose of an intank filter which is usually located on the inlet side of the fuel pump is to keep "trash" out of the fuel pump that could damage the pump. I personally would rather have a blocked filter than to have a damaged fuel pump that would cost a lot more to replace than a filter. On the LS, the fuel pump is relatively easy to get at since you can remove it without dropping the fuel tank, at least on the 93 LS you can. I guess the best way to avoid a clogged internal tank fuel filter is to make sure that you purchase gasoline from stations that use an "inline" filter in their pump supply lines. I normally have a policy of not buying gas from a station that has a tanker there filling up the underground tanks because I believe that they are stirring up all the sediment in the bottom of their tanks and that sediment could end up in my gas tank if the station does not use pump filters. Just my humble opinion.

[LScott400]

Having found a "hidden" filter full of yuck Recently, I have been searching for a preventative solution. There are some manufacturers of a product called a fuel filter funnel. This is a Link to the product info on one. I believe some of the others do not require a grounding strap. Apparently owners of boats and diesel vehicles are primary targets for these products. I just know dropping a fuel tank (NOT necessary on the LS, as previously pointed out) twice in 6 months is enough to last me awhile.

[cleverdick]

Thanks for replies. Interesting about the filter funnel - I might try and get one. In the meantime, has anyone had a bad experience using Wynn's Dri Fuel (or similar) to dissipate any water in the tank? Would the moisture released into the fuel damage the external paper filter? If only manufacturers put drain plugs on fuel tanks, like on aircraft!

[SKperformance]

The filter you are talking about is basically a silt filter it is not really serviceable as it is just to stop large particles from jamming the pump. If the filter was before the pump it would cause the pump to run dry and burn out every time the filter clogged.

The silt filter on the pump is on every single car made as there is always debris from gas stations in there holding tanks. The way to clean it up or prevent it is to never buy gas from a station when you see a refuelling tanker on at the station. It will cause the tanks to swirl and the sediment will become suspended and be delivered to your tank. Also try to never buy gas from older stations with older pumps. I try and buy gas at the same stations all the time . They all are new stations other wise if it does not have the option to pay at the pump i would rather run out of gas before i buy it there. Using a good fuel additive helps clean it up also ,like seafoam.

[baul79racer]

I have a '91 LS400

Regarding where the fuel filter is exactly located inside the tank?

When you pull the carpet cover away from tank there's a sensor gauge on the side as you looking right at it.

And on top it looks like a breather for ventilation.

Do you need to take the back seats out?

I wish I had a manual at this time.

Thanks

Paul

[cleverdick]

I have a '91 LS400

Regarding where the fuel filter is exactly located inside the tank?

When you pull the carpet cover away from tank there's a sensor gauge on the side as you looking right at it.

And on top it looks like a breather for ventilation.

Do you need to take the back seats out?

I wish I had a manual at this time.

Thanks

Paul

Hi,

According to the book, you have to take the back seat out, then remove a cover to access the front of the tank. You then undo a plate and remove the pump which has the filter on it. I have not done this yet, but hope to in the near future. I'd be interested to hear from anyone who has completed this job successfully, what their total miles were and what condition their filter was in.

My car is series 1, 1990.

[baul79racer]

Thanks for the information of how-to.....

I am planning on doing it tomorrow hopefully.

The 1991 Lex LS400 has 174,800 mi.

I already change the first fuel filter on the driver side on 6/28/06. I blow into the old fuel filter and black crud came out.

Well, here is my problem: I was going home on 520 west and I was accelerating hard as the sweet Lex hums it's beautiful quiet engine to big rpms. All of a sudden around the last corner. It's a long "S" corner hitting the last part around 65m.p.h. coming out of 2nd gear into 3rd after hitting 6200rpm with ECT pwr mode on. All of a sudden it lost power as I hold the throttle to the floor. The temperature in WA is 92, As soon I gain control of throttle by releasing the pedal to close I immediately push down on the throttle and ease the girl at a cruising rpm of 2 grand at 60m.p.h. I add more throttle and it accelrate just fine to the point where it hit the 4000rpm - 6200rpm scale and the Lex suddenly "Lost Power" and it feels and hears like it hit the rev limiter if you were to do that. As soon as you hit 4grand it starts the "Lost of Power" 3500rpms drives normal. I lost power and speed quickly.I check the oil, tranny and it check o.k. Just for safety maintainence. Then my mechanic said, it wouldn't be a bad idea to check the fuel filter. Since it hadn't been change since I own the Lex. 3 1/2 yrs. At first I thought it was bad gas in the tank. I first put redline fuel system cleaner. Didn't seem to fix the problem but it may had help it. No, it's too late by then...

So, after I change the first fuel filter I put the brand new Wix filter in the Lex. (reminder it's the driver side fuel filter) test the Lex. Same problem occur "Lost Power" same range 4k - 6200 rpm.

One more thing I took the car to the local Chevron station to a tech. mechanic he said it was a unusual problem meaning more than just fuel filter problem? I said there's should be more testing. But I won't do it until after changing the 2nd fuel filter. I will let you all know how the process went of taking the 2nd fuel filter.

That's my "Lost of Power" story problem....Any suggestions or ideas that would else cause the Lex to lost power in the power band range please add reply.

Thanks

Paul

[cleverdick]

Thanks for the information of how-to.....

I am planning on doing it tomorrow hopefully.

The 1991 Lex LS400 has 174,800 mi.

I already change the first fuel filter on the driver side on 6/28/06. I blow into the old fuel filter and black crud came out.

Well, here is my problem: I was going home on 520 west and I was accelerating hard as the sweet Lex hums it's beautiful quiet engine to big rpms. All of a sudden around the last corner. It's a long "S" corner hitting the last part around 65m.p.h. coming out of 2nd gear into 3rd after hitting 6200rpm with ECT pwr mode on. All of a sudden it lost power as I hold the throttle to the floor. The temperature in WA is 92, As soon I gain control of throttle by releasing the pedal to close I immediately push down on the throttle and ease the girl at a cruising rpm of 2 grand at 60m.p.h. I add more throttle and it accelrate just fine to the point where it hit the 4000rpm - 6200rpm scale and the Lex suddenly "Lost Power" and it feels and hears like it hit the rev limiter if you were to do that. As soon as you hit 4grand it starts the "Lost of Power" 3500rpms drives normal. I lost power and speed quickly.I check the oil, tranny and it check o.k. Just for safety maintainence. Then my mechanic said, it wouldn't be a bad idea to check the fuel filter. Since it hadn't been change since I own the Lex. 3 1/2 yrs. At first I thought it was bad gas in the tank. I first put redline fuel system cleaner. Didn't seem to fix the problem but it may had help it. No, it's too late by then...

So, after I change the first fuel filter I put the brand new Wix filter in the Lex. (reminder it's the driver side fuel filter) test the Lex. Same problem occur "Lost Power" same range 4k - 6200 rpm.

One more thing I took the car to the local Chevron station to a tech. mechanic he said it was a unusual problem meaning more than just fuel filter problem? I said there's should be more testing. But I won't do it until after changing the 2nd fuel filter. I will let you all know how the process went of taking the 2nd fuel filter.

That's my "Lost of Power" story problem....Any suggestions or ideas that would else cause the Lex to lost power in the power band range please add reply.

Thanks

Paul

You might be on to something there... please let us know how it goes removing the pump from the tank.

Other than that, I can only suggest the throttle body may need cleaning.

Best of luck...

[93ls400walt]

I'm having a simular prob. But it is at any rpm, If i accelerate to fast. Engine runs fine otherwise. If I press the gas faster than a smooth/steady push the rpm drops. And the feel of the car is like you are putting on the brake lightly. I get a " puff " like noise from under the hood. I also replaced my undercarriage gas filter. And by chance when I ordered it from the dealer. They sent the in tank filter instead. So I paid and kept it and ordered the right filter. No change in the car after changing the undercarriage filter. I to plan to change the in tank filter. My car throws a Code 41. Which is a error for the throttle speed sensor. I ordered the sensor ( 74.00 ) from Park Place Lexus-Plano, Tx. www.newcarparts.com. It's supposed to be here 7/3. I hope this solves the issue.

Be sure to order a new fuel pump gasket before you take everything apart. I'll post results from the TPS change.

[baul79racer]

Hello This is Paul with the '91 LS400 "Lost Power Story"

Anyway....The fuel pump filter is located behind the back seat. It wasn't that complicated.

The fuel pump was quiet as a snail.. and the filter from it was clean as nails. It's the size of cigarette box and basically it's a screen.

Anyway. My Lex still looses power in the power brand range 4k - 6200 rpms. Once in awhile it get some power to 5k rpms with sluggish hick ups.

I check the "cat" underneath the car it looks fine after running up a hill no signs of hot red glare.

Tomorrow... I looking in on the fuel pressure regulator. Anyone think that's a good idea?

Let me know with any hits or pointers.

P.S. When it lost power it was very hot in Seattle area 92-95 and I believe it got vapor lock in the fuel system.

[cleverdick]

Hello This is Paul with the '91 LS400 "Lost Power Story"

Anyway....The fuel pump filter is located behind the back seat. It wasn't that complicated.

The fuel pump was quiet as a snail.. and the filter from it was clean as nails. It's the size of cigarette box and basically it's a screen.

Anyway. My Lex still looses power in the power brand range 4k - 6200 rpms. Once in awhile it get some power to 5k rpms with sluggish hick ups.

I check the "cat" underneath the car it looks fine after running up a hill no signs of hot red glare.

Tomorrow... I looking in on the fuel pressure regulator. Anyone think that's a good idea?

Let me know with any hits or pointers.

P.S. When it lost power it was very hot in Seattle area 92-95 and I believe it got vapor lock in the fuel system.

Hi,

Sorry to hear you still have the problem, but at least that's one possible cause you've eliminated.

I would have been interested to see the filter - did you take any photos?

How coarse or fine was the screen mesh (compared to something we all know)?

It still might be worth cleaning out the throttle body if you've not already done that; look on lexls.com. Mine was very bad. Cleaning the TPS and doing a proper trans flush and filter change (as per the tutorial), using T-IV, fixed a slight hesitation on my car at around 45-50 m.p.h.

But I really would appreciate a detailed description of that fuel filter and your opinion on how likely it would be to clog up.

Thanks...

[Earl W.]

     I am having this kind of problem as well, my 94 LS 400 looses power or dies when I accelerate for any small period. 
     I replaced the fuel pump and pick up screen, only after I discovered I couldn’t find a in line filter. 
     I still have the same problem and I’m currently searching for the proper fix. So if anyone has a fix, please let me know. Thank you

[1990LS400]

17 hours ago, Earl W. said:

     I am having this kind of problem as well, my 94 LS 400 looses power or dies when I accelerate for any small period. 
     I replaced the fuel pump and pick up screen, only after I discovered I couldn’t find a in line filter. 
     I still have the same problem and I’m currently searching for the proper fix. So if anyone has a fix, please let me know. Thank you

The most direct way to a fix without throwing parts at a problem is to take your car to a professional mechanic who understands these cars.

[vissine]

On 1/22/2020 at 8:43 PM, Earl W. said:

     I am having this kind of problem as well, my 94 LS 400 looses power or dies when I accelerate for any small period. 
     I replaced the fuel pump and pick up screen, only after I discovered I couldn’t find a in line filter. 
     I still have the same problem and I’m currently searching for the proper fix. So if anyone has a fix, please let me know. Thank you

I don't know about your model but inline fuel filter in my car is pretty easy to find and replace. Mine is a 96.

[Abe Scott]

I know these are old post, however on the 99 ls400 there is the suit filter and the filter for the fuel regulator both are in the tank. And of course the online filter on the passenger side near the differential.