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GS - 2nd Gen (1998-2005) Discussion about the second generation GS300, GS400 and GS430 (1998 - 2005)

98 GS400 wont start

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Old Oct 30, 2010 | 05:38 PM
  #16  
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did u replace it with a new battery.. try getting a next battery. I swear i remember having the same problem and my friend came with his battery and for some reason it workd... Its odd that the car stopped working
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Old Oct 30, 2010 | 06:50 PM
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yes. Its turning over strong. I dont hear any noise from the fuel pump. im going to try the trick with compression gauge that the poster on last page suggested tomorrow to see if im getting fuel
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Old Oct 30, 2010 | 09:19 PM
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Originally Posted by pitmanr200
I listened to it with access cover off in back seat with my ear right on it. Heard nothing. Unplugged it and did same thing just to make sure I didn't hear something and not notice it. Do I have to be under car or truck to hear it
You should be able to hear it with the little access port thing under the seat off. You can test it, it takes 12v DC, which is what your car battery is. You can take the battery out of your car, bring it to the back of the car and hook up the plug for the fuel pump with it using some wire. (recommend several feet) But you must be careful to operate the fuel pump like this for only a few seconds. The current is too high from the battery and the pump won't last forever like that, it burn out. So, don't have it like this for more than 3-4 seconds. Before you think I'm totally crazy, This is actually the Lexus approved method for testing it. It's in my service manual. I'm looking at it now. As you are looking at the fuel pump plug There are 5 connectors. Two on the top, 3 on the bottom. The bottom ones you can ignore. We are not using those. (removed what i typed here in my first post as the picture posted below is better than my explanation) Hook up the battery for just a few seconds this way and the pump will activate. If it does not activate, you have a fault pump. It if does activate, then you have a faulty ECU of some kind, or you have a blown fuse.

Last edited by tinman; Oct 30, 2010 at 09:25 PM. Reason: Pic is better.
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Old Oct 30, 2010 | 09:21 PM
  #19  
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From Toyota/Lexus Service Manual for the GS300,GS400 and GS430 models.

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Old Oct 31, 2010 | 10:10 AM
  #20  
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Ok I have a battery charger that putts out 12v. At 6amps. I figured hooking it up like you said would be easier than taking battery back thre. It did nothing. Would this way work as well. If so I have a bad fuel pump right?
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Old Oct 31, 2010 | 10:44 AM
  #21  
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can i just buy fuel pump. I dont know how much longer Im going to own my gs. thinking of getting a newer one. I have seen some aftermarket pumps online for like 60 dollars or amazon has a denso for 142. I dont know if I need fuel pump kit or just the pump. If you all have any suggestions where to get one let me know.
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Old Oct 31, 2010 | 11:15 AM
  #22  
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Originally Posted by pitmanr200
can i just buy fuel pump. I dont know how much longer Im going to own my gs. thinking of getting a newer one. I have seen some aftermarket pumps online for like 60 dollars or amazon has a denso for 142. I dont know if I need fuel pump kit or just the pump. If you all have any suggestions where to get one let me know.
Do you have a multi meter? You can measure the ohm resistance of the pump by connecting the + and - pins to the multi meter. If the resistance is between say, 0.3 and 3.0 then you are ok. If not, the pump has failed and you have your diagnosis. (if the readings are kinda close to this, then you are probably ok too. If the readings are way off, like you get a reading of 300, it's broken)

I'm afraid I don't have any info on aftermarket fuel pumps. I've never installed one. You probably don't need the entire assembly, just the pump.
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Old Oct 31, 2010 | 11:19 AM
  #23  
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Yes I have multi meter and had already checked voltage going to the pump. And got 10
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Old Oct 31, 2010 | 11:32 AM
  #24  
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[ I have never read ohms before so I hope I did this right. I hooked it up and set my meter to the horse shoe looking sign. Which I believe is ohms. I got 2.49. So wouldn't it be good. But when I hooked charger up it made no noise

QUOTE=tinman;5901902]Do you

have a multi meter? You can measure the ohm resistance of the pump by connecting the + and - pins to the multi meter. If the resistance is between say, 0.3 and 3.0 then you are ok. If not, the pump has failed and you have your diagnosis. (if the readings are kinda close to this, then you are probably ok too. If the readings are way off, like you get a reading of 300, it's broken)

I'm afraid I don't have any info on aftermarket fuel pumps. I've never installed one. You probably don't need the entire assembly, just the pump.[/QUOTE]
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Old Oct 31, 2010 | 11:38 AM
  #25  
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Yes, the horse shoe thing is ohms. I don't know the exact specification for your fuel pump, but 2.49 is a perfectly sane value for a pump and should be well within acceptable range.

Can you hook up your multi meter to the wires coming INTO the pump? From the ECU? Turn the key on and see if you get voltage from pins 4 and 5 as shown in the diagram picture earlier.
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Old Oct 31, 2010 | 11:41 AM
  #26  
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Originally Posted by tinman
Yes, the horse shoe thing is ohms. I don't know the exact specification for your fuel pump, but 2.49 is a perfectly sane value for a pump and should be well within acceptable range.

Can you hook up your multi meter to the wires coming INTO the pump? From the ECU? Turn the key on and see if you get voltage from pins 4 and 5 as shown in the diagram picture earlier.
Whops, i just read your second to last post. You got 10v coming into the pump? Is that correct? If so, you have reached the end of my diagnostic knowledge. Sorry.
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Old Oct 31, 2010 | 11:55 AM
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Originally Posted by tinman
Whops, i just read your second to last post. You got 10v coming into the pump? Is that correct? If so, you have reached the end of my diagnostic knowledge. Sorry.
Yes. So that means that its telling pump to come on. But it isn't. Wouldn't that mean pump is bad
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Old Oct 31, 2010 | 12:17 PM
  #28  
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Ok rechecked ohms and got 4.29. I may have meter set wrong. I have it on ohm 20k
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Old Oct 31, 2010 | 12:22 PM
  #29  
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Originally Posted by pitmanr200
Ok rechecked ohms and got 4.29. I may have meter set wrong. I have it on ohm 20k
If you have it set on 20K and you're getting 4.29 then you have a bad pump. Set the ohm meter to the lowest setting (i.e. 20, not 20K) and retest.
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Old Oct 31, 2010 | 12:27 PM
  #30  
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Found the test info.
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