JTom

Where Is The Fuel Pump Resistor On Ls400 1992? Also No Hanyes Manuals?

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A friend of mine is working on my LS400, the car was stalling while idle and also completely died while driving, he set the fuel pump relay to run at it's highest and the car is smooth now, he found the fuel pump relay fine but he can't fine the fuel pump resistor that controls the pressure. I've googled all over, nothing, I also don't see a Haynes or Chilton manual for this car, do they not exist?

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In the shop manual the fuel pump solenoid resistor appears to be directly connected to the

centre tap of the FP relay, marked PR.

Using an ohmmeter the resistance between the terminals is shown

as 0.67 - -0.79 ohm at 20 degrees C [68 F.]

replace if out of spec.

Assuming Europe spec. is the same as USA!!

Hope this may help

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In the shop manual the fuel pump solenoid resistor appears to be directly connected to the

centre tap of the FP relay, marked PR.

Using an ohmmeter the resistance between the terminals is shown

as 0.67 - -0.79 ohm at 20 degrees C [68 F.]

replace if out of spec.

Assuming Europe spec. is the same as USA!!

Hope this may help

On my '90 LS400, the fuel pump resistor is bracketed to the wheel well hump, down below and to the side of the fuel pump relay. Here's a picture:

90-LS400-Fuel-Pump-Resistor-sm.jpg

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I have a 96 ls400 that was running fine. I drove it about 10 miles and then pared for about an hour. When I tried to leave, it wouldn't stay running. It had no power and was idling all over the place and trying to die. Giving it gas had no affect on it. 

I had it towed home and planned to work on it today. I started it and it ran fine but I wanted to find the problem. I had done some research and determined it was probably the fuel pump relay or resistor. 

I disconnected the resistor and tried to start it. It showed the same symptoms as the previous day and wouldn't stay running. I plugged the resistor back in but it still is not running correctly.

My ohm meter is measuring 1.1-1.2 so I'm assuming the resistor is shot?

Looking for a second opinion...

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I'm at the junkyard and found one but the ohm meter reads 1.1, the same as the supposedly defective one

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The relay and resistor had no change but now the car won't start at all. 

Going to exchange for fuel pump.

MAF sensor?

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You can use a paper clip jumper on the diagnostic connector, between the Fp and B+ I think it is terminals to bypass the fuel pump resistor and relay and see if your pump runs.

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This a 96 and the diagnostic box inder the drivers side dash doesnt have a  fp or b+

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You really need to re read the title to this thread..........................!!!!!!!!!!!!!!!!!!!!

The year is a 1992.   Not a 96........................................

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7 hours ago, Exhaustgases said:

You really need to re read the title to this thread..........................!!!!!!!!!!!!!!!!!!!!

The year is a 1992.   Not a 96........................................

Feel better?

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Not really. I would think a person would start a new thread for their car problem, and not use or resurrect one from 7 years ago that doesn't even apply to the car in question. Its like asking for help on an aircooled VW beetle on a Lexus forum.

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My question was based on a post in this thread about the ohm resistance of the fuel pump resistor.

You're a troll looking for confrontation. 

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On 3/15/2017 at 11:02 PM, bdruff said:

It was a faulty fuel pump. Easily replaced

I saw this and was going to point this out because mine started to do the same thing now that it's getting warmer. For others with this issue, the best way to check for fuel is to put your ear to the fuel fill hole and have someone put the key to on. If it doesn't whine it's not working. I hit the tank a few times while my buddy tried to start it. Started right up. The pump is getting hot and seizing up. Hitting it got it to loosen up for a bit. It did start running bad about 30 minutes later. But at least I knew what it was. Replaced it and it's been good ever since.

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Gentlemen,

I know I am the FNG(F'in New Guy) but if I may be allowed a suggestion. If both gentlemen would consider the solution is for B17what to cut and paste his dilemma, discussion and discovery on a whole new blog or post with the title 1997 Lexus etc to get the best solution to the scenario. It's the goal intent of the lesson to learn but also will pay it forward to the next 97 ls400 owner from pulling hair out ordeal trouble shooting can be. That way, Exhaustgases makes a valid point and B17What helps the next 1997 two fold by not leaving his answer in 1992 limbo and that is what everyone wants and needs in the end. Sorry and thank you for the knowledge because this blog looks exactly parallel to my 1993 problem my local mechanic can not track down and by all parties posting their experience, I have a straight map of things to one by one find, test and not get frustrated when I think it's one part and get no answer. I then know from you folks being so kind, what my next question to ask instead of being a Yosemite Sam in front of the neighbors.

thanks
 

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