25 replies to this topic

[xsaint53]

I have a '95 SC400, I got it a few months ago... I took it in for an oil change a few weeks ago and the tech said that you don't need to replace the fuel filter in the SC400... I don't think it has ever been changed. Right now it has about 188K on it...Recently it has been running kinda rough... When I accelerate at relatively low speeds (20-40 MPH) it SEVERELY hesitates and almost feels like it's going to die out...Once I get going at a decent speed (40+ MPH), everything seems fine, but when I go from a stop or slower speeds, I notice severe hesitation.. I'm hoping it's the fuel filter, rather than the injectors or fuel pump.. Any help/advice is appreciated... (Note: I don't have tools and I'm not very mechanical..So any work would have to be done by a professional mechanic)... Just trying to see what I'm up against.....Thanks and hope everyone is having a Great Xmas Season....

[1992LexusSC400]

First and foremost, you need to replace the fuel filter.. Its on the driver side behind the door , just before the rear tire. Just jack up the left rear side of the car and you will see it. Get a fuel filter from Autozone or Oreilys... Or the Stealership.. Be careful and DO NOT strip the brass couplings. Make sure you have a very good grip or ratchet when prying it loose and tightening it back up. You will need to disconnect the battery cable and let it sit for about 10 minutes, this will stop the fuel from running out the whole time you are trying to work with you under the car.. Some fuel will run out, this is normal.. If it keeps running out get a container to catch the remainder fuel in and reuse it... Try this first and see where you are at on the hesitation.. Lastly, run a can of Seafoam through the brake booster vaccuum line.. Does wonders.. Hopefully its not your fuel pump... Very uncommon in the SC400's. Might be you fuel ECU, but try the simple things first....

[xsaint53]

First and foremost, you need to replace the fuel filter.. Its on the driver side behind the door , just before the rear tire. Just jack up the left rear side of the car and you will see it. Get a fuel filter from Autozone or Oreilys... Or the Stealership.. Be careful and DO NOT strip the brass couplings. Make sure you have a very good grip or ratchet when prying it loose and tightening it back up. You will need to disconnect the battery cable and let it sit for about 10 minutes, this will stop the fuel from running out the whole time you are trying to work with you under the car.. Some fuel will run out, this is normal.. If it keeps running out get a container to catch the remainder fuel in and reuse it... Try this first and see where you are at on the hesitation.. Lastly, run a can of Seafoam through the brake booster vaccuum line.. Does wonders.. Hopefully its not your fuel pump... Very uncommon in the SC400's. Might be you fuel ECU, but try the simple things first....

Thanks!! How much would a shop charge to do this?? Also what is the "ECU"?? As I said, I'm not mechanical. Thanks for your help...

[xsaint53]

Oh, one more thing....... I notice a mild "gas smell"..... and when the car is cold and I start it. smoke comes out of the exhaust pipes for a second.. a"blueish" smoke, and only when I first start it up....the smoke stops after that....I'm not sure if that has anything to do with the fuel filter/injector possible issues....

[1992LexusSC400]

Everyone will charge you different on the replacement of the fuel filter. I think you can do it, if you have some basic tools and a jack. Even if you use the tire change jack on your car. I believe the threads are a 10mm or a 12mm size.. I would not take it to a Express Oil Change place and do it, thats my opinion, and from my experience. The ECU stands for Electronic Control Unit.. If I am not mistaking.
About the cold start issue, it could be a cold start injector, but double check on that one. The blue smoke is usually a oil leak from internal. I dont know too much on that topic, but I know the 93-98 supras were bad about smoking on a cold start. I forgot exactly what that cause was, but I remember it was a problem for those cars. Lastly, could also be a fuel injector leaking for the slight smell of gas.. Does it dissipate after a few seconds, or a few miles while driving.. Sorry I couldnt help you any more..

[1992LexusSC400]

Dont forget to run a half of can of Seafoam through the brake booster line and follow the instructions on the can.. Might help with your problem, but it will improve the throttle response...Its the cheapest at Wal-Mart.

[xsaint53]

Everyone will charge you different on the replacement of the fuel filter. I think you can do it, if you have some basic tools and a jack. Even if you use the tire change jack on your car. I believe the threads are a 10mm or a 12mm size.. I would not take it to a Express Oil Change place and do it, thats my opinion, and from my experience. The ECU stands for Electronic Control Unit.. If I am not mistaking.
About the cold start issue, it could be a cold start injector, but double check on that one. The blue smoke is usually a oil leak from internal. I dont know too much on that topic, but I know the 93-98 supras were bad about smoking on a cold start. I forgot exactly what that cause was, but I remember it was a problem for those cars. Lastly, could also be a fuel injector leaking for the slight smell of gas.. Does it dissipate after a few seconds, or a few miles while driving.. Sorry I couldnt help you any more..

The gas smell does not dissipate...It's kinda noticeable, especially when I turn off the car....ALSO, about how long start to finish should it take for the fuel filter replacement?? Thanks again, I appreciate all your help!!

[PatrickB]

Where is that brake booster line located? I'd like to try the Sea Foam treatment...

[LexSC400328]

i wish i had a picture to show you but here it goes...it is on the drivers side of the engine towards the rear of the engine. its a small black rubber hose thats is bent downwards and goes straight into the top of the head.
here is a youtube video of someone doing it. good luck

[1992LexusSC400]

The brake booster line is the black hose, close to the firewall, directly above the pcv in the youtube video. It has a bigger opening in it for a funnel. Thats the one that I use to seafoam, just make sure you tighten it back, either one you decide to use.

[sc4sooner]

hey its your catalytic converters not your fuel filter.

first off you can not get a fuel filter from auto zone or orileys they will not fit properly, they claim to but they dont, trust me i had the chemical burns to prove it. your tech was right the fuel filters on these things almost never need to be replaced.

all of the problems you listed would be caused by the cats being bad. unfortunatly it is a more expensive fix, but it will fix your problem and it will be a whole new car once you have it done.

[1992LexusSC400]

SC4sooner, You can get a fuel filter from Oreilys, and yes you do need to change the fuel filter. This is where I got my filter from and it worked perfectly... No problems

[sc4sooner]

i have 113k on my 92 sc4 and when when i tried to replace mine with one i got form auto zone not only did the new one not fit, but when i did the good old breathing test through the old one i was just as easy as the new one, and i know it had never been replaced before, so i put the old one back on.

i still sand by my comment on his problem being caused to catalytic conveters that have gone bad, the problems he is describing are the exact same problems my dad was having on his 97 BMW 740iL and after replacing the cats it ran like new.

[92BlueByU]

I tried replacing mine with a Beck Arnley (sp?) and it would not go on. I didnt need it, but I have a 92 with 170k on it and I tried doing it as preventative maintenance and it would not go on.
If the threads are different, about all you could do is cut the line before the filter fitting find a flare nut with a little bit of hard fuel line coming out of either end and then use rubber fuel line hose and clamps to put it back in line.
I had chemical burns from high octane and smelled like gas bad. The gas kept coming and coming I dumped about 3 gallons before I tightened it back up and called it quits.

I took it to a mechanic I trust they tried it, it wouldnt go on. They got another one (Fram) it wouldnt go on. To be sure your going to get the right one get one from the stealership.


You have a couple things you can try, if its an ealier model like mine (92) you can unplug the AFM from the air intake tube and see what happens. My AFM went out so instead of paying up to $1k for a new one or buying a used one with no warranty I unplugged it and it hasnt given me any problems at all. I can smoke the tires at will, no strange sounds, no hesitation unless the tires loose grip.


Also if you look on you tube I think someone has posted a video about adjusting the throttle position sensor you could also try that.


Are the spark plugs newer, when was the last tune up?

[1992LexusSC400]

SC4sooner, I totally agree with the cats making the stange gas smell. I cleaned or gutted my front cats out. It makes a hollow sound now, but it runs a little better. I was just simply stating that the fuel filter that I got from Oreilys worked, without any problems. No stripped threads, or nothing that previous people were stating about.