1up

99 gs400. Was driving home on I-10 yesterday when the car started to sputter, tank read between 1/4 and 1/2 remaining. Thankfully I was close to an exit and so I sputtered in "on fumes" to the gas station just barely making it. Filled up and noticed it only took 12 gallons, wtf? Car ran 100% fine after that.
This is my gf's car, and she said it did the same thing when she first got it @ 1/4 tank, so she always kept it over that. I just figured it was an inaccurate gauge reading, so never worried about it. But "running out of gas" when there is ~7 gallons left(nearly half the tank)....something else is up.

Bad fuel pump? Clogged fuel filter?

nelson09

iTrader: (3)

Float in the tank could be off, meaning it reads a 1/4 when it should read empty. That happened to me the second day of owning a previous car only mine was on e but read 1/8 of a tank.

MikeFig82

iTrader: (13)

Have a look at the link below. It sounds like your fuel gauge sender is bad. I found the diagram to test the sender before. I'll see if I can find it and add it here.

https://www.clublexus.com/forums/gs-second-generation/593459-00-gs300-fuel-pump-issue-need-some-guidance.html

1up

Even if the fuel gauge sender is broken, or the float is broken..etc That wouldnt account for the car not running when there is still 7 gallons left in the car right?. I see from the link posted above that there is a siphon tube that connects both parts of the tank, I think this might be the culprit as I dont see what else would cause this specific problem.

Thanks for the replies.

1up

Anyone have the exploded view of the gas tank? Just want to see what the humps/siphon tube look like before diagnosing anything else. The sewell link no longer works.

mveale

iTrader: (5)

I mean, something like this is REALLY unlikely, but it's possible...

http://www.e30tech.com/forum/showthread.php?t=28865

TL;DR: Guy buys E30 M3, fills the tank on "empty" and it doesn't take as many gallons as it should. Turns out there's a hidden pocket cut into the gas tank for drug smuggling purposes.

Mr Jokster

iTrader: (8)

Definitely not a sender issue, evidently these guys dont know how big our tanks are. You are correct. Last week I was just under a quarter tank and I put 11.5 gallons in and it wasnt full yet. You're on the right track with diagnosing, is this the blow up you're looking for?

1up

Thank you very much for this. I will update the thread if I find a solution.

ntran18

iTrader: (27)

That's a big discrepancy...

The most I've ever filled up in the tank was 18 gals. That was running on E for a quite while.

MikeFig82

iTrader: (13)

I found this while searching for a vacuum hose diagram. It states on how the suction from the passenger side gas should work. Though it doesn't state if the guy fixed his problem or not.

http://www.justanswer.com/lexus/869t5-lexus-gs-400-99-gs400-need-replace-valve.html#re.v/173/

LeoLex126

Not exactly sure if this is the solution but going to try it tomorrow. I believe in theory its just like changing your brakes. Just like the brake system the fuel system is pressurized. I have a 98' and a 00' GS300 and both have had this same problem, been dealing with this for months. I check back on this thread periodically to see if anyone has found a fix. I believe there's a purge valve on pretty much all fuel systems, the same way you would have to bleed your brake lines to release any air in the system I think once you open the fuel system we have to purge it to get the air out the lines. Gonna attempt it tomorrow, put a small gas tank in the trunk and try to take it down to E. I'll update once I get there.

jeepandlex

Mine is off by an eighth of a tank lol. I've run out of gas twice thinking I had enough to get to the station.....it's wifey's car, and she has a knack of getting to the house with just enough fuel. I always pass the first station because the gs likes mobile lol....and I've paid twice. Now I tell her to fill up just under a quarter tank. I'm not gonna fix it unless it gets worse....the car's a 98. Actually considering a 2012 300 5.7 When we hit 150k

NickTee

That's why having an electric vehicle is nice: you can always leave the house with a full "tank."

tiguy99

Did you ever figure out what the problem was?

Paul1307

Please check the following thread:

https://www.clublexus.com/forums/gs-...15-code-2.html