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Old 07-23-13, 08:51 PM   #31
BobSmith00
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Originally Posted by Yamae View Post
Sorry that my suggestions were not effective but you are stepping to the conclusion on e by one. Your efforts and the reports are about to catch the rat.
You already has confirmed that:
1, The "ECU" is not disabling the 12V supply to the fuel pump,
2, The "Fuel Pump Resistor" is not open,
3, The "Fuel Pump Relay" is supplying currents that may be a bit bigger than normal because the wire was warm when bypassed.

The 3rd item is quite important. Is it possible for you to measure the current by ampere meter?
If not, bypass the "Fuel Pump Resistor" using a bulb for a brake light or equivalent instead of a wire to know the current level by the brightness. If any bulb is not available, try again using a wire again and feel the warmness and the change of it from the start to may be up to 10 seconds using your finger. I want you to inform me the result.

I am not good at speaking English but may be I can talk to you over the phone and let me give you some more. Inform me your phone number using the personal message to me, I will call you up.

If I checked it correctly, I got 3.77 volts from short circuiting 3 and 4.
PM incoming to you Yamae.
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Old 07-23-13, 09:06 PM   #32
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Your efforts and the reports are about to catch the rat.
I just love catching the rat!!
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Old 07-23-13, 10:12 PM   #33
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I am very glad to have had the assistance from the other side of the world. We did not find the rat yet, but soon will find it, I am hopeful.

Again am very much happy to see the suggestions and help from folks, it really is good. Vs me not having a clue what to do next.
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Old 07-24-13, 12:24 AM   #34
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As I talked to you, Bob and asked you to measure the currents, things confirmed were

1, "Circuit Opening Relay" passes through 4.6A ,
2, "Fuel Pump Relay" passes through 2.59A
3, These currents are mostly stable.

What I can say by these are that the "Fuel Pump Resistor" is functioning and bypassing 2.01A of current. The fuel pump is driven well at least at the start up.

The fuel pump motor is consuming 4.6A and this means that the resistance is 12V/4.6A=2.61Ohm. This is a bit bigger than I know but it's not too much. The "Positer" in the fuel pump is not limiting the current since the current continues until the engine is shut off.

The rat is still hiding. I will be investigating some more with above results and inform you later.
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Old 07-24-13, 02:18 AM   #35
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The rat is still hiding. I will be investigating some more with above results and inform you later.
Interestingly, I have seen many car electrical and running problems caused by a real rat! - they eat the wiring harness! - there is even a thread on Club Lexus about this problem on an LS400 right now!

I lived on a heavily wooded lot, and to prevent rats in the engine compartment, I spray the engine area and the underside of the car with an alcohol and highly concentrated habanero pepper extract mixture, then when the rat tastes the wires, their mouth is on fire!
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Old 07-24-13, 05:50 AM   #36
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The photo below shows the way to force to work the "Fuel Pump" whatever does the ECU at the "DIAG Connector". With this method, (short circuiting "Fp" and "+B") turn the ignition key to the position "RUN" and confirm that the "Fuel Pump" starts to work. You should be able to hear the humming noise from the pump. Then you turn the key to start position. Does your engine start and keep running or stop soon?

Above method does not cause any harm and you don't need to worry about as long as you connect "Fp" and "+B" properly.
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Old 07-24-13, 10:42 AM   #37
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Originally Posted by Yamae View Post
The photo below shows the way to force to work the "Fuel Pump" whatever does the ECU at the "DIAG Connector". With this method, (short circuiting "Fp" and "+B") turn the ignition key to the position "RUN" and confirm that the "Fuel Pump" starts to work. You should be able to hear the humming noise from the pump. Then you turn the key to start position. Does your engine start and keep running or stop soon?

Above method does not cause any harm and you don't need to worry about as long as you connect "Fp" and "+B" properly.

I opened the cover on the DIAG port. What I saw was a bunch of grease of some sort. It seems like someone has used the DIAG port before and maybe was too rough with it. I am not sure.

The "Fp" seems to just be a hole that goes all the way down to the base, I could not see any sort of contact to be used to short circuit with "+B"

"+B" seems to have something I can actually touch with a wire, but I am not 100%, I am still cleaning the greasy stuff off so I can get a better look.
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Old 07-24-13, 01:52 PM   #38
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I opened the cover on the DIAG port. What I saw was a bunch of grease of some sort. It seems like someone has used the DIAG port before and maybe was too rough with it. I am not sure.

The "Fp" seems to just be a hole that goes all the way down to the base, I could not see any sort of contact to be used to short circuit with "+B"

"+B" seems to have something I can actually touch with a wire, but I am not 100%, I am still cleaning the greasy stuff off so I can get a better look.
extra bits of knowledge.
1) I was correct that Fp was just a hole, and that +B had something in it.
2) Used a meter on +B, with the Key in the run position it had 12V

Here are photos.
Click the image to open in full size. This is the top view with +B in the red box, and Fp in the Yellow Box.

As you can see from this bottom view, Fp has no wire while +B does have a wire, again +B in red, and the missing Fp Location in yellow.
Click the image to open in full size.

So I wasn't able to do this test of shorting Fp with +B to have the Fuel Pump active in the Run Position.
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Old 07-24-13, 04:43 PM   #39
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Originally Posted by BobSmith00 View Post
extra bits of knowledge.
1) I was correct that Fp was just a hole, and that +B had something in it.
2) Used a meter on +B, with the Key in the run position it had 12V

So I wasn't able to do this test of shorting Fp with +B to have the Fuel Pump active in the Run Position.
So the Fp terminal in USM is not wired. Sorry for my insufficient direction.

Instead of shorting Fp and +B, is it possible for you to supply the DC12V to the pump directly and try starting?
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Old 07-24-13, 05:05 PM   #40
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So the Fp terminal in USM is not wired. Sorry for my insufficient direction.

Instead of shorting Fp and +B, is it possible for you to supply the DC12V to the pump directly and try starting?
It has started raining very much, I am not sure If I can apply the DC12V today or if it must wait.

But If I was to supply power to pump, wouldn't there be some power going back up the wire powering the pump normally? Would I need to remove the Fuel Pump Relay?
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Old 07-24-13, 06:01 PM   #41
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It has started raining very much, I am not sure If I can apply the DC12V today or if it must wait.

But If I was to supply power to pump, wouldn't there be some power going back up the wire powering the pump normally? Would I need to remove the Fuel Pump Relay?
You don't need to remove the Fuel Pump Relay as long as you supply the 12V from your battery in your LS400. When you use an external power supply unit, it would be better to remove it.
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Old 07-25-13, 06:30 AM   #42
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I don't know if it's because I'm hopped up on Dayquil with last nights Nyquil still in effect but this thread is a great read. It's like a novel with drama, suspense and the hero doing everything he can to save the day with the help of a wise man half the world away. ::dramaticmusic::
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Old 07-25-13, 10:32 AM   #43
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I don't know if it's because I'm hopped up on Dayquil with last nights Nyquil still in effect but this thread is a great read. It's like a novel with drama, suspense and the hero doing everything he can to save the day with the help of a wise man half the world away. ::dramaticmusic::

That Dayquil isn't nothing to mess with, in my much younger days, I drank quit a bit of it one day when Sick. And I distinctly remember the effects it had on me. The most lasting effect was when I passed out/went to sleep and woke up like 40 hours later, in a pool of my own drool. But I did feel better. So I guess it was a good tradeoff.
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Old 07-25-13, 10:38 AM   #44
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Originally Posted by Yamae View Post
You don't need to remove the Fuel Pump Relay as long as you supply the 12V from your battery in your LS400. When you use an external power supply unit, it would be better to remove it.
Will be doing this today, assuming the weather holds up. Will report back findings.

Edited with news:

The weather while hot, was not raining, so I was able to supply 12v to the Fuel Pump itself. I could hear the fuel pump functioning. I turned the key, It did the same as has before. Seemingly powering up the fuel pump for a short time before attempting to start the car had Zero change to its behavior.

Another test.
Using a vacuum port on intake manifold, attached an alternate gasoline fuel source.
Car ran for 10 seconds. The Car ran roughly, and only died after it had sucked all the gasoline out of the container attached to vacuum port.

Last edited by BobSmith00; 07-25-13 at 03:23 PM..
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Old 07-25-13, 03:24 PM   #45
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Updated the first and last post with more information and today's tests on the car.
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Old 07-25-13, 03:24 PM
 
 
 
 
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96, bad, beavis, belt, butthead, bypassing, ecu, fuel, hd, lexus, ls400, pressure, problem, regulator, symptoms, tensioner

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