eicca,

The problem with the Lexus gas tank is that it is a "saddlebag" design. The tank is somewhat "U" shaped, but sits upside down so that each side is isolated from the other. The gas pump sits in the left "saddlebag" and constantly pumps gas up to the engine where only what is needed is used and the rest is sent back to the gas tank. The returning gas runs through a tube also on the left side, which siphons gas from the right side of the tank using a venturi-effect mechanism. Any excess from the right "saddlebag" would flow back over the hump in the middle of the tank, which keeps, in theory, the left side of the tank (with the pump) always full of gas even while the right side is being drained down. In theory, anyway. What seems to happen occasionally in practice is that the air pressure in the tank becomes so low that either the siphon no longer functions, or, worse case, the siphon works in reverse, diverting gasoline into the right saddlebag while the left saddlebag (side with the pump) slowly goes dry until the engine suffers fuel starvation and stalls out completely. The primary symptom is that upon filling the tank it's discovered that four-to-six gallons of gas are still in the tank, but on the right side only where the gas pump is unable to scavenge the gas. Open the gas cap and add a gallon or two of gas and the tank vacuum is broken and the added gas allows the pump and siphon to work correctly again. And yes, long trips do seem involved where one would fill the tank then drive continuously until the vehicle stalls out, the vacuum in the tank slowly, but relentlessly increasing until it affects the operation of the siphon, the right side of the tank retaining gas, the left side having gone dry.

 

Right. What I was getting at is that a malfunction in the evap system could be causing the gas tank to vent properly and that this is likely the same problem I'm experiencing on my Land Cruiser. If I happen to figure it out, I'll post it and people can see if that helps their problem too.

 

Exactly! On the one hand I hope you don't have any problems while on the other I hope we can all learn something if you do.

 

I called Lexus support on Monday of this week and was told to expect a call back in a day or two. So far, no call. I'd like to think someone is actually giving some attention to this and actually researching it, while on the other hand I could understand how a problem related to a 1998 GS400 might not be a top priority. One way or the other I'll be calling again next week to do some follow-up work to see what they might have to say.

I would like to mention that I spent about three hours on the phone with a very knowledgeable woman who seemed to know Lexus vehicles inside and out. She said that she had never heard of this problem before, and it took me a while to come up with a scenario that she could relate to, but once we got past that point she seemed to understand it quite well. It's nice to know that Lexus listens when we talk. Whether or not they're going to devote any time to a problem occurring on a 1998 GS400 or not is another matter altogether, but I have some hopes. I'll add to this post when I have some further information, and hopefully Lexus will have something to offer.

BTW, I was also told that my car is in the recall over the air-bags. As it was put to me, they will either have the parts in stock, or "You'll be driving a rental car for six months" presumably at Lexus expense. I asked if I'd get my choice of rentals, a GSF being my first choice, and she laughed and said that's not likely, but that the rental would be a Lexus, regardless.
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Which dealership was it? I'd like to talk to her.

and 2) I'm a-gonna get my airbags checked for recall because yeeeaaaah I'd enjoy an IS350 for a day or two!

 

Paul,

BTW, I was also told that my car is in the recall over the air-bags. As it was put to me, they will either have the parts in stock, or "You'll be driving a rental car for six months" presumably at Lexus expense. I asked if I'd get my choice of rentals, a GSF being my first choice, and she laughed and said that's not likely, but that the rental would be a Lexus, regardless.
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This air bag recall, is for only GS400 o for all GS and all years? More info. please.
Thanks

 

Called the dealer. No recalls whatsoever for me.

 

That would be nice!

If we could dream, I'd love to try the new RC or GS models

 

It wasn't a dealer that I talked to. I called Lexus support directly, a number I found on their website. BTW, I haven't heard back yet, so it's time to call again I guess.

 

So have been driving the car this week...mostly city driving and have even let the gas go close to where it stalled in my thread which was about 3/8th of a tank.Symptoms I've observed:1. Some what rough idle in drive unless AC is running (500rpmish)2. Yesterday cranked the car but it wouldn't start. Had to step on gas pedal with the ignition on "on"a few times then crank the car. It started up fine and hasn't done that since. Have driven a few times since with no issues. Haven't filled up either. From what I'm reading about the EVAP VSV issues, these symptoms are quite common. Have also seen the EGR valve may be impacted. Paul what are your thoughts on these things?

 

tiguy99,

It's always tough trying to do a long-distance diagnosis, especially when I'm not a Lexus mechanic, nor do I work on my own car, and I'm certainly not an expert on anything automobile-related. I'm an engineer who used to get paid to resolve problems that existed in very large complex systems where no one of months had been able to locate the source of the problem. From that perspective have I approached the "cut-out" problem I and others experienced, by looking at the system and system components and developing a theory. In my job, developing a theory was followed by experimentation and analysis, followed, if necessary, by more observation and another theory to be tested. I don't know that I've correctly "solved" the "running out of gas with five gallons left problem" but I have defined what I think are the critical points surrounding the event(s). I'm now doing the best test(s) I can with my car, by popping the cap periodically, and, by letting my gas level run down. So far, in the heat of AZ, every time I pop the gas cap, the smell of gasoline tells me that the pressure in my tank is positive, that is, higher than ambient, which is what you'd expect when the heat of the day causes the gasoline vapors in the tank to expand. So far, I have not experienced any "whooshing", and I'm down to almost a quarter of a tank with no gas starvation events. I expect that pretty soon the light will come on telling me I'm running short on gas and I'll have satisfied the question of whether or not gas is being transferred from the right "saddlebag" to the left under "normal" driving conditions. And there have been no CEL events.

In an effort to compare my car to yours as you've described the conditions, I started it cold (relatively, as it's 94 in Phoenix today), immediately turned the A/C off, then let the car come up to normal operating temperature (the second line on the temperature gauge at about 8:00 o'clock), and only then did I turn on the A/C. My results were this: cold, idle was at about 1250 RPM, and it slowly dropped down to about 790 or so until operating temperature was reached, all this while the car was parked. Turning on the A/C dropped the RPMs very little, less than 100 RPMs, maybe to 780 or so. Putting the car in Drive dropped the RPMs to a very steady 600 RPMs either with or without the A/C turned on.

My first thought on your questions is this: do you have any CEL activity, and have you run diagnostics on the car? The cost of a diagnostic package, software and dongle, is about $25 or so, about one-third what lexus charges for a diagnosis, and from my experience the diagnosis kit is complete, runs a full battery of tests, checking every system from the operation of the side mirrors to the ignition and fuel system. If the diagnosis doesn't come up with an error code then you don't have any, ANY faulty components that need replacing. Don't go swapping parts just to swap parts - this goes especially for the EVAP system, EGR or VSV, canisters, fuel pumps, or any and all of the rest. If it ain't broke, don't fix it, and diagnostics will tell you when something isn't working correctly, certainly the marvel of this or any other age: computers. Suggestion: get some fuel injector cleaner from AutoZone or its ilk, two bottles of it, let your tank run down to 1/4, then put both bottles into the tank and run the car until the gas light comes on. It's amazing what fuel injector cleaner can do (and when the dealer says they cleaned the injectors, guess what they do? Yup, dump a bottle of injector cleaner in the tank). I always run Slick-50 in every car, and I've seen and experienced what that stuff can do. An old 4-cylinder pickup-with-carb idled up about 200 RPM and could pull hills in 4th gear I used to have to pull in 3rd, so I know it works. Can't hurt, right?

I've always had my cars serviced by Lexus, and I think they've been very nice to me. Though not always cheap. I recently needed new brakes, rotors, and a master cylinder: $1,000, but it was all done in hours: could I have done it cheaper? Probably, but sweating it out in the AZ sun for days in the process, not to mention the hassle of having my wife "help" me bleed brakes; no thanks. Another time in Sarasota, FL my Lexus mechanic, and it always seems as though the same mechanic at a dealer always works on my car, offered to put in an OEM rack in my 2005 RX that was $500 less than the Lexus part. He checked my HIV headlights, told me I needed a new ballast on one side, then told me "the job's not too tough, you could probably do it yourself, and an OEM ballast is only about $100." Lexus price: at least $500. I took his advice and did it myself. In Dallas, TX on a work trip my car stalled stone dead. Then it started back up, but stalled again later. I had it towed to Lexus, then remembered something: the radio had reset the buttons to 87.9, ergo, the battery was becoming disconnected. Bingo! I called the Lexus shop, asked to talk to the mechanic, then explained what I suspected. He agreed, fixed it, then told me the negative connector was loose, and only charged me about $45 because he said he didn't have to do any diagnosis, so didn't charge me for it. In Lubbock, TX where I had an "incident" of "out of gas" (actually about 50 miles from Lubbock) they kept the car in the shop for two days, tested it every way they knew how, then only charged me about $100 for the diagnosis because they couldn't find a thing wrong, "had to charge you something," and it drove them nuts. And we were towed into town, and lived 1500 miles away! In Phoenix, when we lived in Prescott, I talked to the head mechanic, told him the steering was getting squirrely, asked if there was an adjusting nut to tighten it up like on recirculating ball steering. He looked at me, tilted his head a bit, smiled, and said "maybe I can find something." He later told me that he'd "found a service bulletin that covered it" (I think it was a wink-win, nudge-nudge moment, but never really knew), charged me about $75 for "diagnosis" and when I got the car back it steered and handled like a brand new car driving on rails, and five years later, still does. Maybe I'm just lucky...

I always treat my mechanic with real, honest respect; I don't act like "I know the game, you try to rip me off and my job is to argue about what you know or don't know." I always ask to talk to my mechanic when service tells me something needs to be done, and they always come out, talk for a little bit, then take me back into the shop and under the car to point and commiserate. I'm respectful of their opinion to a fault, perhaps, try to speak like I know something about cars, always ask questions, and always ask for their opinion of what they'd do if it was their car. They always love seeing a GS400 that's still on the road, and service records will tell them I've owned it since 2000. I always ask for explanations - "It's okay; talk technical to me" - and I've never met one who wasn't thrilled to shift gears and talk technical, show me what it all looked like, what they were doing, and why, and they love to talk about what they clearly love doing. We look at diagrams together, talk about what the components do and why. Commiserate on possible causes. I walk under a car on a lift like I've been there before (which I have) and not like I'm afraid the car will fall down on top of me. I wear jeans and a polo-style shirt; I don't "dress" to go to the dealer EVER, even when I'm looking to buy a car (they don't think I look like I can afford what I'm looking at? Ever seen a successful farmer looking at cars? Bib overalls, dirty shirts, s*** on the boots, tractor cap, and then they pay cash for a new one and drive it off the lot. Their loss, not mine. I've had mechanics spend as much as an hour just shooting the breeze before telling me they need to get back to work on the car so we can both get out of there. Lexus service expensive? You didn't buy a Yugo so don't act so surprised, but honestly, my GS400 has been one of the least expensive cars for servicing that I've ever had, and it's still probably got another 100,000 miles on it. The most expensive repair I ever had done was replacing the A/C, about $3,000, but really, after 18 years it finally went bad? I can't complain.

My point? Don't write off Lexus service, they're not out to rob you blind (in spite of what some others may say), but do get a diagnosis kit from ebay first, and run every test you can. If you still really think there's a problem that's not showing up on the diags, approach the dealer's service department, explain the issue and let them take a look at it. They will charge you for diagnosis (probably the same tests you'll run yourself), but if they do find something, and you don't want them to do the work, they'll tell you what it needs, what it will cost, then let you leave if that's what you want. btw, with the diagnosis kit you can also program new keys, a savings that pays for the kit five times over. Don't just shotgun problems; seek expert advice (and the dealer IS the expert); then do what you want.

 

This is indeed an interesting thread.

1) About four years ago I ran out of gas with 1/4 tank showing on the gauge. I attributed this to a stuck float as I had recently replaced my gas tank. Thinking back, I now realize that I had been driving on the highway on and off for about five hours. If I recall now I may have also had a P0715 code.

2) About three years abo again after driving for about four hours I ran out of gas, this time the low light had just come on about 5 miles before.

3) A couple of weeks ago I was on a long road trip . Twelve hours on the first day. On the second day after about three hours driving the car suddenly burped, then threw a CEL code 0715 and then a few seconds later stalled out. The gas gauge showed about 3/8 tank remaining. I towed the car to a gas station put $20 gas and I was on my way. I continued on the road trip without incident for four more days averaging about 600 miles per day. I made sure I never got below 1/4 tank again.

Since the first incidence of "running out of gas with more than a 1/4 tank" I have tried to fill up before I reach 1/4 tank empty. Occasionally I have run below 1/4 tank with out incident but of course I rarely let this occur.

After reading Kevin's experience, I am inclined to think that my fuel pump may be a an issue but then I also see merit in some of Paul's comments. I do have a relatively new OEM gas cap. My car also throws the P0446 code occasionally. I simply reset the code. This has been happening on and off for well over five years maybe closer to six or seven. My car also throws the P0171 code on and off. This also has been happening for three or four years. Originally I attributed it to my K/N filter but I went back to stock six months ago an the code still comes back from time to time.

I too am not ready to simply change out my fuel pump or my charcoal canister or anything else for that matter until I can definitely identify the root cause of these symptoms.

Just thought I would throw this info out there for people to ponder and maybe collectively we can come to some conclusions on the common elements here.

 

Just as a side note I was getting the P0446 code for a long time as well, several months if not years. The dealer finally narrowed it down to a rubber hose that had cracked and gone bad over time. So check the hoses around your purge valve (you have have to lift your engine cover to see them):

 

Thanks, I have read about bad hoses causing the p0446 code before and plan on doing a thorough check for this once we get out of the deep freeze up here.

 

Is that a 1UZ or 3UZ? My 1UZ doesn't have that valve.