My 1994 Lexus has a rather sudden and dramatic drop in MPG.

Asked by Oldlexus Mar 14, 2013 at 11:00 AM about the 1994 Lexus LS 400 RWD

Question type: Maintenance & Repair

I've had this car for 9 years, and during this time I've always gotten 19 to 20 miles per gallon. In recent months it dropped to 14 MPG and was running rough. My driving habits have not changed at all. I've had the following work done:
Full tune up ($800)
Replaced 02 sensor
Replaced mass flow meter
Replaced timing belt and water pump
Since then, my MPG has actually gotten WORSE. It's down to about 10 MPG.
It has 158,000 miles on it and has been a great car. One thing I notice is that when I start it up in the morning, there is a very strong smell of gas around the car.
Fuel pump? Thermostat problem? Any ideas? I love this car but am running out of money to put into it.

2 Answers
176,095

tenspeed answered 11 years ago

Gas smell would point to a fuel problem. Have the fuel regulator checked. The regulator has a diaphragm. The engine vacuum pulls on it and the excess pressure is sent back to the tank. If the diaphragm ruptures, raw gas is sent into the air intake and fuel pressure at the injector nozzle increases. Both conditions result in a very rich mixture and decreased MPG's. --- Usually on a older vehicle the O2 sensor response slows down and signals more fuel than necessary at the injectors. Since you replaced the O2 sensor, that can't be it. -- I repeat, have it checked and tested before replacing to make sure it is the cause.

1 people found this helpful.
Mark helpful

Your Answer:

Related Questions

LS

Looking for a Used LS in your area?

CarGurus has 32 nationwide LS listings starting at $5,995.

Postal Code:

Shortcuts

Search Lexus LS Questions

CarGurus Experts

  • #1
    HenryProctor56
    Reputation
    530
  • #1
    Paul
    Reputation
    530
  • #3
    dandyoun
    Reputation
    480
View All

Find great deals from top-rated dealers

Search

Related Models For Sale

Used Lexus GS
25 listings starting at $9,999
Used Lexus ES
17 Great Deals out of 214 listings starting at $5,900
Used Mercedes-Benz S-Class
19 Great Deals out of 203 listings starting at $6,500
Used BMW 7 Series
10 Great Deals out of 134 listings starting at $8,499
Used Toyota Camry
51 Great Deals out of 1,099 listings starting at $2,500
Used Toyota Avalon
3 Great Deals out of 36 listings starting at $6,995
Used Mercedes-Benz E-Class
34 Great Deals out of 511 listings starting at $5,450
Used Honda Accord
52 Great Deals out of 978 listings starting at $2,995
Used Chevrolet Corvette
29 Great Deals out of 782 listings starting at $15,900

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use. Content will be removed if CarGurus becomes aware that it violates our policies.