Over the past few weeks my car has been experiencing accelerating problems, starting problems, and now sometimes won't start. I changed my fuel filter thinking it was it and I think I got air in the fuel system. Im not sure how to bleed the air out, when I attempt to start the car it just stalls or dies. Any help would be appreciated.
When i replaced it I did not open the gas cap, I will be redoing it today and opening the gas cap to let the pressure out, and undo the filter and put it back up. I have no check engine light and no codes

 

Hello,

What is the mileage on the car?
Does the CEL light up when the key is in the ON position?
How did the issue first begin, was there any service done to it?
When was the last time maintenance like Timing Belt, Spark Plugs, etc. done?

It is not a Diesel engine, so the air being trapped in the system is not that much of a concern, so long as there is no opening in the system that allows the air to be sucked into the system at all times, but it is very unlikely.

Check the Pressure Dampener on the Fuel Rail, there should be an exposed Phillips screw on top of it, see if it is raised from the surface, which would indicate that there is pressure in the system. Check that it stays raised as you run the car and open the throttle, otherwise it can indicate fuel delivery issues, like a bad fuel pump.

You also wrote about relieving Pressure in the tank, does the pressure collect in there and you have to take the cap off once in a while? Those cars are equipped with systems to purge fuel vapor that builds up in the tank as it sits, and allow fresh air to enter the tank to displace the used fuel, so there shouldn't be any need to open the cap and relief the pressure, if the pressure does build up, you have a problem somewhere in the EVAP system, and the fact that CEL is not on with this issue can raise suspicion.

Depending on when was the last time spark plugs were replaced, you can take at least a few of them out and check their condition, see what kind of residue is on them, and if the residue pattern is similar on all the ones that you took out. While at it, it won't hurt to check the compression as the plugs are already out, it's a simple procedure that can prevent a lot of unnecessary work.

If non of that will help, you will have to find an OBD2 scan tool, and look at Engine Live Data, paying close attention to Fuel Trims, as well as MAF and A/F sensors. Here you can learn more about Fuel Trims, they need to be as close to 0% as possible, anything greater than 10% is a cause for investigation, you will have to whether it is a Rich or Lean mixture, and go from there.

Here is a thread on how to check A/F sensor, in short, check that the readings are close, but not stuck on 3.2-ish volts, if that's good, floor the car for a split second, the readouts should immediately go to Rich side, and level out, if there is a considerable delay, the sensors are bad.

MAF sensor should read about 3.5 - 4 g/sec at idle, if it is more, the sensor is likely getting old and either needs to be cleaned, or replaced altogether. If it is less, there is a chance you have a vacuum leak, as the air finds its way around the sensor, the readouts drop as well.

Hope this helps and best of luck!

 

to start off with I was very surprised of your response I appreciate it very much.
It has 272xxx miles, the CEL light does turn on in the on position.
The issue began about a month ago but it was very minimal, the car maybe twice a week would seem to have a lack of power and acceleration, sometimes i would have to get off the gas pedal for it to "fix" itself and it would, just like nothing happened. At first I thought it was a vacuum leak, because at the time I would use my code scanner and it would read P0171 too lean bank 1, but when i would start the car the CEL did not come on, but it would in the on position.

To my knowledge no maintenance has been done to the car other than what i've done myself. when I went to replace some things myself I noticed "ghetto" fixes.
Last year I replaced my spark plugs, one had oil on/in it because (what im pretty sure is the cause)there was too much oil in car which I didn't know about until I went to do an oil change and collected about 7qts of oil from the drain plug. I replaced the thermostat twice, and i've replaced the radiator and maybe two vacuum lines.

I ended up taking it to a lexus/ toyota shop early on when I was experiencing issues, but whenever they drove it they wouldn't experience the issue so it wasn't any help. When they scanned it for codes the code did not show up either, and there also weren't any erased codes, so essentially the problem "fixed" itself like it usually did.
The temperature outside or temperature of the engine doesnt have an impact of when it happens, it just seems to be random. The rpms do not increase during the issue either, it just seems like im not getting fuel is what I was thinking.

Taking the cap off the tank was just something I guess I was supposed to do while i change the fuel filter, just so air doesnt get trapped, causing an air lock?

over the month the issue became more persistent, and intense. At this moment my car no longer starts, I did replace the fuel filter, and it wont start.
two weeks ago my car had stalled when i went to the store, when I was ready to leave the car wouldn't start, I ended up calling a tow. The guy was an ex mechanic he said. He had me try to start the car while he looked at the engine, and when I did a he began tapping on my throttle body housing which helped it start. so he recommended I replace the housing. I accessed the housing and it seemed completely fine, barely a layer of gunk, I cleaned it while I had it open.
A few days later I was leaving school and my car stalled not even half a mile from where I was, I asked a friend to try to start my car while I did what the tow guy did, this time nothing happened so I got it towed home. When it was home it started right up like nothing happened.
I replaced the fuel filter, it wouldn't start. I ended up finding the sherader(bleed) valve on the fuel rail and attempted to release any air trapped but nothing came out. At this point I believe it might be my fuel pump that has failed? I checked the fuse for the fuel pump but since its a solid color plastic on top I can't actually tell, but the prongs looks completely fine. I also dont hear a hum when i put the car in the on position, which I read that I should hear a hum because it's the fuel pump charging.
Tomorrow I will be taking my car to the lexus/toyota shop and see if they can figure it out, I need it running by next week for work.

 

Lean code doesn't usually resolve itself, and a couple of small vacuum lines being lose usually not enough to cause it to appear, so it is something I would look more into with the scan tool, it is something that can very likely cause your problem.

While you can and will trap air in the fuel system as you replace the filter, it won't take long for the pump to drag it through the system, and since petrol cars don't rely on extreme pressure in the system, air doesn't get compressed and doesn't affect them as much.

While too much oil in the system can cause a plethora of unpleasant surprises, it shouldn't increase its pressure, or cause to to get trapped in the combustion chamber, so there may be a different cause for oil in combustion chamber. With such mileage, it could be that the engine itself is experiencing problems, like seized piston rings, depends on the service history, those cars are tough but not indestructible.

Not sure if they still have it, but earlier models came with an Idle-Up valve that was designed to increase Idle if the pump was experiencing more load than expected. Those valves tend to develop a leak, causing the ATF from the Power Steering system to be sucked into the engine, causing oil in the combustion chamber, and a general appearance as if the engine has seen better days.

How does it feel when the car lacks power, does the car start to vibrate, misfire, or does it just feel as if the throttle is released? Not sure how tapping the throttle body fixed anything to be honest, it could be that the motor that drives it is a little worn by now, causing the throttle to not open when you press the gs pedal, but I haven't heard of too many of them failing. One way to see if that's the case is to take the intake pipe off and look at the throttle body as you press the gas pedal, see if it opens fully, and that it does so quickly.

What about the Timing Belt, when was the last time it got replaced? Those should replaced every 80,000 miles, and its failure in VVT-i engines will cause severe damage, so it is something you need to keep an eye on, it is better to replace it sooner than later. Always replace it as a kit with Water Pump, those are maintenance items and are not designed to last much longer than a belt itself.

Hope this helps and best of luck!

 

Got the call from the shop I took my car to, they said my fuel pump was failing and that was the reason I've been experiencing these issues. I gave them go to replace it. Over the phone I mentioned I'd like to be notified if I should have any maintenance done to it, more specifically the timing belt and water pump, the lady over the phone said they could possibly check the condition of the belt but they'll let me know. I'm curious if there's any crucial maintenance I should have done on it, to last me the best. Money currently isn't a huge issue, i've saved quite a bit for this car because I knew it would cost to keep it well. I don't have the slightest idea of what maintenance keeps LS400's lasting so long but any help would be wonderful. Thank you

 

have you had the ECU capacitors replaced? that can cause a lot of unexplained issues in 90-97 cars