iatimlee

FIXED!!! I installed a new pump this afternoon and the car starts and runs fine now. If anyone is looking for a tutorial on fuel pump replacement, you'll find one at Lextreme(dot)com/fp(dot)htm, but its for a '90-'94. The '95 and up had a few twists in getting the seats out: To pull the seat back out, there are the four 13mm bolts across the bottom but there are also 3 across the top - one behind each headrest (you'll find a corner of the leather is curiously not stitched down) and one behind a velcro flap hidden behind the center armrest near the top of it's cubby hole. Don't forget to carefully pry open your seat belt retainers or use a philips screw driver and remove them from the top of the seat back so they can stay in the car with the belts. I broke 2 of mine trying to pry them off :( ...so, a word of caution. Learn from my mistake. Once all 7 of those bolts are out and the seat belt retainers are detached, the seat will just come straight out. No need to 'push in and lift up to get it off the hooks'. There are none.... After you've got that out of the way, remove the sound dampener mat (it's not glued down or anything, just sort of draped over the mounting tabs from those head rest bolts and tucked under the rear deck about an inch or two). Everything else is the same from the '90-'94 tutorial. I would recommend a new gasket when you go in. They aren't cheap but you don't want to risk fuel leaks (fire, evap emission codes, smell of gas fumes in the cabin, did I mention FIRE?) right behind the passenger compartment. They're less than $15 (most places are less than $12) and it's a real thick rubber - not a standard gasket that I would want to re-use, especially since it takes so much effort to access. It would be like reusing valve cover or intake gaskets. It's just not worth it. After I had the new motor installed, I checked the resistance and this time I got 4.5 Ohms (above the Lexus spec, but this is a Denso part so I'm not worried). By the way I spent $120.23 +S&H for the pump plus another $11.87 for the gasket. It all came from drivewire(dot)com. Too many different pumps come up to choose from so I took a shot at a mid range price that was a denso unit.

Try Factory Car Stereo Repair at carstereohelp(dot)com. They are in Florida. A guy named Bob runs the place and he was fantastic to work with when I sent my Nak head unit in from my '95 LS400 back in May of 2008. He services all sorts of high end factory radios and amps and even has some DIY fixes with pictures posted on his site - lots of good tutorials on removal and diagnosing also. He treated me right and after bench testing my unit for a week, he didn't even charge me. I was having tuner issues, but all he did was open it up and inspect it. It's worked great ever since. Great communication too. Highly recommended - super knowledgable.

Update: I grabbed a few parts from Radio Shack and made a harness to run power back to the trunk: Radio Shack 2700344 2 pack of battery clips $3.00 2700015 in-line mini fuse folder $3.00 6403132 22-18ga 3/16" spade connectors M/F $2.50 Wal-Mart (wire) 18ga wire (automotive section near fuses) 40' $4.50 ea for red and black You'll need a fuse also, but you can use one of the spares from the fuse panel under the hood if you don't have any others. I would recommend a 20A. You'll also need a way to splice the end of the fuse holder to your power carrying wire (electrical tape will work but a crimp butt connector is better). When I tried to start the car with the power run from this configuration it still wouldn't start although once or twice it did stumble for just a split second. I measured the current that the motor was drawing and was shocked to see ~15 amps (verified multiple times at 14.5 to 16) steady - it never dropped. I wish I would have pulled the fuel line from the rail on the intake to verify 100% that it was not pumping, but there was no obvious sound or feel at the delivery line so I don't believe the pump ever came on. I think it's stuck. I measured the resistance at the battery clips (with them removed from the battery of course) and had 1.0 Ohm. I had measured 0.6 Ohm at the pump terminals previously so I figured my connections were good. I wish I could verify that the fuse on the tutorial diagram in your link (great site by the way, I poo-pooed it initially because of the name, but I guess you can't judge a book by it's cover or a website by it's name) was EFI#1. If my pump is pulling 15A continuously then whatever fuse feeds it must be stressed or over driven when anything else wants power AND I still wouldn't have an explanation for my 20A fuse blowing repeatedly if it's not EFI#1. So my next move will be to replace the pump and gasket. I've done some preliminary searches and found prices from $50 to over $300. Can anyone pass on a known good source at a reasonable price? I'll go to the Lexus parts counter if necessary but I've found that even my local Toyota dealer can supply the identical part for considerably less most of the time. I'm thinking there's got to be a good web source out there some where (?).

I've read through several threads dealing with fuel pump issues (several seem to start after a long period of no use...hmmm) and did not see many with resolutions, but I did find some good troubleshooting ideas, but my apologies if this has been dealt with in another post and I missed it. When I find the solution, I'll be sure to post it. Background info - About 2 years ago my 95 LS400 (135k mi) developed the usual power steering leak that so many have seen. I nursed it along by topping it off whenever it growled and eventually I had to park it since my wife was about to give birth to our first baby and I just didn't have the time to rebuild the pump. I think my alternator is probably gone as well due to the leak - but that's all auxiliary information. My OBDII scanner says there are no codes stored and everything else in the car is operating as expected (radio, dash, etc.). The real issue - I recently returned to the project so that I could get it back on the road. I knew the battery was probably going to be bad and it was. It was 8+ years old when I parked it so no complaints there. It was due. With a brand new Lexus branded Interstate battery the engine turns over but never fires. What I've done to troubleshoot - With the engine turning over fine, I grabbed a gas can and got 3 or 4 gallons of fresh gas and dumped it in the tank (it was below an 1/8 but the tank was holding pressure when I unscrewed the cap). I figured I've diluted the old fuel enough with the fresh gas to make it tolerable. Still no fire - not even a stumble. I sprayed a couple shots of starting fluid in the air intake and hit the key and it started right up and ran for a second or 2. So I'm assuming that I've got good spark. Next I checked over the fuse block under the hood and discovered that the 20A fuse for the EFI#1 circuit had blown - all others tested good with a DVM. I replaced the fuse and there was no difference. I verified the fuse had not blown and then continued my diagnostics. I pulled the fuel pump relay and checked resistance of the coil and continuity of the contacts and then used a small ATV battery to test operation of the relay outside of the car. It all checked out. I checked for voltage at the relay socket with the key off and also in the on/run position and found no battery voltage or voltage of any kind for that matter. I then went to the 'circuit opening' relay and verified it the same way I did the fuel pump relay. It all checked out fine - relay is operational but for this one full battery voltage is present at the socket. I set aside the clue about the fuel pump relay socket having no voltage and removed the trunk lining to get to the fuel pump connection. I disconnected it and verified the pump resistance at 0.6 Ohm (Lexus manual says 0.2 to 3 Ohm is normal). Sounds very low to me but it's in spec although I could not detect any sound, hum/vibration or anything that made me believe the pump actually ran when I connected it directly to the battery for 2 seconds at a time. I know there was a connection through the pump because when I pulled the power away from the connector there was a small spark due to the coil of the motor not having a discharge path I suspect. After all this, I left the pump disconnected and went back to inspecting the relays and fuses. There are some things somewhat out of order in my timeline above. I've been doing this over the last week or so whenever I have spare time in the evenings. I say that because I discovered that same 20A EFI#1 fuse blown again last night. I replaced it again and verified that I still have no power to the fuel pump relay socket. I can't really say when the fuse blew but I know I have not shorted anything out during my testing. I initially thought the fuel pump must be stuck and shorting out but I can't find an electrical layout to know if the fuel pump draws from that EFI#1 fuse. The only thing I haven't looked at is the fuel pump resistor, but I don't get ANY sign of voltage at the fuel pump relay socket with the key in the on/running position so the resistor isn't even in the circuit at this point and I still don't have power to the relay. Question - Could the dead relay socket be a fuel cutoff from a security issue due to the long time with a dead battery? Where does the power for the fuel pump relay come from and what is its purpose? It's a NC relay so applying power to it opens up the contacts. According to the Lexus manual, and confirmed by my testing, the fuel pump relay opens a circuit when activated.

There are several Lexus/Toyota specific used parts places out there. I did a quick web search the other day and found quite a few. Not sure of the rules about posting links to non-supportng sites, but if you PM me, I could send you a few.

OEM = Original Equipment Manufacturer Once I got my ECU back from upgrading at Auto & Truck in FL I went for a short (5 mile) drive to be sure the car ran OK. The next time I drove it was a few hours later when I went to the airport to pick up my wife. The car died at the airport exit which was 32 after miles of 70MPH driving. The new ECU only had 47 miles on it and it was showing the same symptoms. It idels down to 200 or 300 almost every day on my way to work after a non stop 17 mile trip at 70MPH. It may only die once or twice a week on that leg of the daily trip. I had always wondered if this issue was related to aging parts - otherwise it shoudl have been more visible at time of purchase and Lexus woudl have been in for a recall and/or a lot of customer dissatisfaction - a lose-lose for them and the owner. I initially thought about investigating the fuel system but I stumbled onto this thread and decided the ECU was the obvious starting point. I also couldn't reason how restarting the car would 'fix' a fuel delivery problem. Regardless, a fuel filter is cheap enough and worth doing so it's going on my list - along with spark plugs. Speedy - can you please post a scan/copy of your receipt from the dealership so we can see specifically what 'related sensors...and other parts that are in relation to pumping fuel from the fueltank to the engine and "giving" fuel "back" to the fueltank" they serviced? Maybe it's not in English but could translate the components for us?

I'm including a copy of the letter (minus my personal info, of course) that I sent with my ECU when it went to FL. I dealt with Alan there and he seemed to be aware of the problem and I mentioned to him that I had been referred to them by this thread. It sounded to me like regardless of what the ECU is sent to them for, the hardware is verified first and then any program updating is performed. I have always had a problem with the argument that this fix was software related - maybe I'm adding that, but I really thought I saw somewhere that the upgrade was strictly a programming upgrade. It seems to me that if it's softwaer it would be more repeatable and should have been there from day 1. I do have the exact symptoms you describe. The car runs like a champ until I get out on the highway and hit 65+MPH for any distance - then it idles down to 150 to 300RPM and dies, either on the offramp or at the stoplight. As soon as I put it in neutral and restart it idles great again - could this be the TPS resetting itself to a home position? The TPS is almost certainly in a different position at 60MPH vs. 35MPH, right? I also have the off throttle shock problem where the car jerks and kicks when you let off the throttle anywhere between 40 and 65. I do use the cruise and I've had problems off and on where the cruise resume does not work. I have to reset it after I've hit the brakes, but not every time - maybe 40 or 50% of the time it doesn't work. Does ATE do cruise rebuilds? Anyone got a source for those? I haven't done plugs yet but I suppose it's time. I've put 50,000 on the car as it's second owner without doing them yet. I bought it from the Lexus dealership that did all the maintenance (I've even got their records) so I'll see when the last set were installed. I've got a few things to check, I suppose. I was just hoping the ECU was the magic bullet. Are you thinking I still have a bad ECU? My original ECU was the 89661-50221. I specifically asked that it be upgraded to the newer Lexus programming in 89661-50224. I'm going to call Alan back at ATE and see what can be done. Thanks for the quick replies. If I have to pull my ECU out again (and it looks like I will), I'll take pictures and try to create a DIY tutorial. Sounds like there is a need. ECU_work_letter.doc

I got my ECU back yesterday afternoon from Auto & Truck in FL so I installed right away. After a short 10 mile trip to verify everythign was working fine I was happy with the upgrade and put the rest of the glove box back in place. A few hours later I had to drive to the airport to pick up my wife and after a 30 mile trip at 70 MPH, I came to the exit and when I got to the stop light the engine idled down to 200 RPM, bounced around just a little and then died - exactly like it used to. The 'off throttle shock' that causes the jerking when letting off the accelerator seemed less but not completely resolved. Needless to say, I am disapointed. Including shipping I spent just under $400 and I can't tell that they did anything. I specifically stated that the ECU was functioning and was only being sent in for the software upgrade. I'll pull the throttle body to be sure I don't have something hung up in there, but I can't reason why that would only be an issue after long highway speeds. Anyone got any comments? I'm lost now.

Yo, I just pulled my ECU a few minutes ago. I didn't think to take pictures until after it was too late but you're past that point anyway. I saw 2 options for removal - remove the 2 phillips head screws from the top of the ECU that hold it to the bracket OR remove the bracket with the ECU and seperate it after removal. I chose the latter because it looked easier. A matter of choice I suppose. If I remember correctly, you have a Nak just like mine (?). This adds a little extra work over the standard stereo. There is a small aluminum box behind the cd changer that needs to come out to get good access. There is a power plug on one end and a pig tail plug connected to this box that goes intot he back end of the changer. Pull the pig tail straight out - it's sort of like a mini version of an antenna plug. There are two 9mm nuts holding this box in place (one on each side). After that is removed you will get access to the door control box. Not sure what this box is for. I thought the key fob receiver was in the trunk (?). Anyway it's a small black box mounted to the bracket that holds the ECU in place, but it's the last think blocking access to the bolts. Once you get it out of the way, the last 2 nuts on the ECU/cruise assembly bracket are easy to get to. FYI - ecudirect.com is not able to upgrade ECU's - only repair them, but they do work with suppliers that can get a tested, working, upgraded model from a donor car. I'm waiting until this afternoon to see if they have a part for me. If not, my ECU is going on Spring Break in sunny West Palm Beach, FL to visit the guys at Auto & Truck Electronics for the software upgrade. I'll keep you posted. Let us know what your results are too. Tim

I'm in the same boat - '95ls400 with a Nak and a bad ECU. I have held off replacing it only because I haven't had time to get it shipped out to Florida. This is the first time I've heard of a 'stereo code'. What is this all about? I undestand the idea behind losing memory settings when disconnecting the battery but what does that have to do with the stereo other than losing presets on the radio? Even if it did do something, what are you supposed to do with the code once you've got it? Is this the anti-theft code so that the head unit can not be used in another car? How is it handled on a replacement unit (used, junkyard, new...)?

Awesome information Bob!! I am one of those 20 guys you mentioned that had posted a question, heard nothing and moved on because I thought I was the only one. This is exactly what is happening to my '95 LS400. It started at around 100,000 miles and has got progressively worse. Two days ago, the check engine light came on after 10 minutes of highway driving speeds and now will not go off. I've got everyone of the symptoms you've described - low idle speed leading to stall after highway driving, jerking/clunking when letting off and then back into the accelerator when someone cuts me off, etc... I'll be looking for a new ECU and I'll post the results of my replacement when I get it completed. I just wanted to say thanks not only for doing the research but posting in such detail. The info here is VERY valuable and I'm going to ask my wife for a GOLD membership for Christmas. Thanks again!