1990 Lexus LS 400 - Page 4 - Answered Questions & Fixed issues

it will have a dead miss or will not run

Hi. Not exactly sure what your looking for ..... The fuel is delivered to the engine via a fuel rail and each cylinder has a injector to deliver fuel to that cylinder.

Fuel is pumped into the fuel rail at 35 psi from a pump in the fuel tank.....don't worry, never heard of one causing a fire. There's not enough air in the gas tank to support a flame.

There is also a 'throttle body' to allow air to enter the engine but iit is not like an old carburettor also delivered fuel.

If you look in the engine bay you will see the cables that operate the throttle body. there will be two cables, one for the throttle controlled by the drivers pedal and one cable operated by the cruise control.

Hope this is some help.

go to the auto parts store they can most likely tell you what it is and maybe change it for you tip them well

Find a better mechanic. How can a battery POSSIBLY overcharge with the alternator disconnected? plus you NEVER should disconnect battery or alternator while engine is running. A voltage surge could wipe out the ecm.

sounds something like o2 sensor?
Best reguards, Premium FixYa Team

One or more of the pulleys is out of line or the idler or tensioner is defective and coming apart, the best thing to do is have them all pulleys checked for misalignment to stop this, many times the crankshaft pulley separates from the rubber ring that dampens crankshaft vibrations and the pulley walks outward. It takes a trained eye to see these pulley alignment issues, suggest you have a trusted shop look at this for you. Even a slight misalignment will eat up or throw off the belt.

take out the back seat.

You need to test your Engine Control Unit (ECU) for fault codes.
This could be caused by several things:
- Coolant Temperature Sensor or circuit
- Intake Air Temperature Sensor or circuit
- A/C Signal circuit
- Power Steering Pressure sensor or circuit.
- Neutral Start Switch circuit
- Throttle Position Sensor or circuit
- Idle Control Valve or circuits
- ECU

You can check fault codes by placing a jumper between terminals E1 and TE1 in the check connector.
(See pictures below) Turn the ignition switch on and count the flashes of the Check Engine light.

If it flashes 2 times every second, this is normal (No codes present). If a fault code is present, the first group of flashes is the first digit in the 2-digit code. There will then be a 1.5 second delay and the second digit will be output. If there is more than 1 code present, there will be a 2.5 second delay, then the nexy code will begin tobe output.
It is recommended that you read the codes (flashes) several times to make sure you are reading them correctly.

Here you can find the guide about how to How to Change Valve Cover Gaskets 1990-1994 Lexus LS400 (images included).

You have one legend vehicle, so, its possible that you are interesting in obtain the Repair Manual.

Keep us updated.

On both sides of the headrest spokes are little adjuster rings. Adjust the headrest up to the highest position. Push down on both of the adjuster rings. While doing that, pull up on the headrest and it will pop right up. Here is a link to help you with all other questions: http://www.clublexus.com/forums/ls400/18383-trying-to-remove-front-seat-headrest-on-ls400-dont-want-to-break-it.html

Thanks for choosing FixYa and welcome to the site. You need to make sure that your fuse is good. The fuse may be blown. Next, if the fuse is good, you may have a bad wire or a bad fan. You will need to test the wires with a voltage meter to determine which one it is. If the fan is getting power, the fan is bad. If it is not, it is a bad wire.

the head rest built inside the seat, you have to take car to a upholstery shop, to replace head rest. best to keep head rest because head rest was made with the seat to keep head neck stable in case of a car accident.the head rest keep you from getting broken neck on a hand on impact.head rest was made for your safety also seat belts. you need them both.

Hi again,

Any developments with your Lexus?

fuel gauge don't work sound like the fuel sending sensor is bad ,and the speedometer check your fuses under hood ,also check that the speedometer cable is not loose from transmission

Make sure the battery is fully charged. Try jumping it or using a jumper box.

The fuel gauge is control by the pump assembly in the tank. You would have to replace the fuel pump assembly to correct the issue.

You will need to disable the alarm.

You no longer need to time engines like you use to in the old days. The computer advances and retards the timing depending on the information the computer is receiving from the sensors. Years ago you would adjust the distributor by twisting it while reading the degrees on the crankshaft sensor, with a timing light, and setting it to a desired spec. This is no longer necessary. Thanks and good luck :O)

possible fuel leak. lay under the vehicle and trace the fuel lines from the gas tank to the engine. if you find any wet spot on them that you know is gas replace them. especially on mpi vehicles, they need pressure to operate

there is a fuse box under the driver side dash near the pedals. you must first remove the protective cover from the outside and then you can see the fuse control panel.