LS400BOY

Hello all,the wifes car 92 ls400 just cut off on her while driving to work and it wont start back up feels like it catches for a sec but wont stay on,i remeber her running out of gas a month or so and said it cuts off on her from time to time, could this be the fuel pump went out? Should i start with the fuel filter? Or is there anything else that could cause this? Desperately need help fellas

randal

First thing is to check for codes -> http://www.lexls.com/tutorials/intro/codereading.html

If no codes, here is list of things to consider -> https://www.clublexus.com/forums/ls4...ml#post8263261

LS400BOY

Thanks,i do not have a scanner but should i hear the pump come on from the rear if i turn the key? Seems like i dont hear anything,i swear when i use to drive the car i would her the pump noise?

sha4000

iTrader: (1)

You don't need a scanner. The procedure to read codes is i the first link he posted. The code, if you have one would go a long way in diagnosing what's wrong. You should hear the pump priming itself when you turn the key to the on position. Maybe you could turn the key and have your wife listen in the trunk for it.

randal

You can try listening for the pump but the problem is that you may not hear it because it may not be running, yet is good. The pump comes on long enough to boost the fuel pressure, then turns off when the pressure gets to 47psi or so. Much like a well pump in a house. It does to run all the time, only when needed. So, a noise is not necessarily a good test. You can pull the fuel pump relay and check resistance to the pump but not sure if you want to go that route. It could even be the relay itself. But it is all speculation at this point. If you want to pinpoint this problem and not throw unnecessary money at it, you will need to follow a method of attack. The second link helps to do that.

As mentioned, you do not need a scanner for your 92. Just follow the jumper instructions in that first link. Its worth the effort to see if the ECU is trying to tell you something.

LS400BOY

Ok thanks guys im going to look into that link again didnt have a chance to fully look because i was trying to get it towed home

LS400BOY

Well i got the car home now,i remembr i use to hear the fuel pump before i turn the car on because it has that fuel pump sound to it but now when i turn the key it does not make that noise instead its making a on and off noise and clicking from the raer?? Is that the noise of a bad pump???

randal

It sure is looking like it might be the pump but first, you need to check something.

Locate the fuel pump relay. Good, now that you found it...you did find it didn't you? ;-) (hint: located on front of passenger side inner fender well). Pull the relay and with an ohmmeter, check the resistance from pin 4 to ground. That will place the meter directly across the pump winding. Report back with the reading.

LS400BOY

Ok thanks for the heads up on location,ill try to do that today after work if not ill try to do it tomarrow due to it being dark by time i get home

timmy0tool

iTrader: (7)

rare the relay would be bad, but start there. i suspect the fuel pump as well which is more likely. it could be intermittent.

LS400BOY

Yea it got to late for me to test that module,but say it was the pump what are the best to run with? I seen 2-3 brands at autozone, and i heard you can change it threw the back seat or trunk? Is that true? Because she just filled up the tank uhhhh lol hate to drop the tank on a full tank

randal

Personally, I would stay away from Autozone, Advanced, PEP, etc for a fuel pump. And stick with an OEM type. Yes, more money but considering your time and the reliability, it will be well worth a bit more.

[edit] removed reference to SC400..not applicable. Thanks Timmy.

timmy0tool

iTrader: (7)

you do NOT have to remove your gas tank to get to the fuel pump! just access it from the inside by removing the back seat.

http://www.lexls.com/tutorials/body/rearseat.html

the pump can be accessed from the circular cover as seen here! ignore the red arrows.

dicer

Yeah OEM is nice, just like starters. But the correct brand from anyone else will be good too. You can try Rock auto, O reillys , Autozone etc. If you stay away from Made in China all should be good.

LS400BOY

Thanks for link and video will look at it after work,wow the gas tank is right behind the back seat!!!