Car won't start, fuel pump staying on
Car won't start, fuel pump staying on
I figured I'd post here since the SC400 has the same engine.
So my mom's 93 LS400 will not start. The car cranks hard and you can hear the starter trying but it just won't fire up. Also, when I take the key out I can still hear fuel moving in the engine bay and I can hear the fuel pump on in the trunk. I checked the EFI fuse and even swapped it out but it still won't start.
We just replace the battery but I still can't get it to start, not even by jumping it. Any ideals CL?
So my mom's 93 LS400 will not start. The car cranks hard and you can hear the starter trying but it just won't fire up. Also, when I take the key out I can still hear fuel moving in the engine bay and I can hear the fuel pump on in the trunk. I checked the EFI fuse and even swapped it out but it still won't start.
We just replace the battery but I still can't get it to start, not even by jumping it. Any ideals CL?
But there's still a major problem, the fuel pump stays on still when I turn the car off. I located the main EFI relay and swapped it with other relays but that didn't do anything. Also, I tried unplugging the fuel pump ECU in the trunk to see if that would turn off the pump but it didn't.
So basically there is a relay somewhere that is giving power to the fuel pump even though the car is off... and it's not the EFI relay.
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Lexus Test Driver
Joined: Aug 2009
Posts: 1,520
Likes: 1
From: CA
so, its always "ON" even when the car is off? "ON" for how long? Till the battery dies? I also would have thought that when you unplug the fuel pump ECU that the pump will shut off immediately.... Are you the first owner? Maybe previous owner mess with the wiring and wanted it constant? Maybe there is an on/off switch somewhere and he bypass the ECU completely?
At least you got it fired up now... just a matter of troubleshooting the fuel pump from turning it off.
At least you got it fired up now... just a matter of troubleshooting the fuel pump from turning it off.
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so, its always "ON" even when the car is off? "ON" for how long? Till the battery dies? I also would have thought that when you unplug the fuel pump ECU that the pump will shut off immediately.... Are you the first owner? Maybe previous owner mess with the wiring and wanted it constant? Maybe there is an on/off switch somewhere and he bypass the ECU completely?
At least you got it fired up now... just a matter of troubleshooting the fuel pump from turning it off.
At least you got it fired up now... just a matter of troubleshooting the fuel pump from turning it off.
I am not the first owner but I know that the fuel pump has not always been constant, this is a recent thing.
Lexus Test Driver
Joined: Aug 2009
Posts: 1,520
Likes: 1
From: CA
I'm still trying to figure out why the fuel pump does not turn off when you unplug the fuel pump ECU. That module seems to have been bypassed. You said it just started recently??? hhmmm I suppose you need to check all the connections, grounding....
When you disconnected the fuel pump ECU, the fuel pump should turn off... It does not make sense why it is still on but its off when the fuse or relay has been disconnected... There is a short somewhere over there
When you disconnected the fuel pump ECU, the fuel pump should turn off... It does not make sense why it is still on but its off when the fuse or relay has been disconnected... There is a short somewhere over there
Last edited by masagsxr; Oct 8, 2009 at 04:02 PM.
aaaaaahhh!
So I thought I had fixed it but something new happened today. While I was driving, slowing down to a stop sign, the car died. It wasn't a loss of power, just a loss of fuel.
The good news is that the fuel pump does not stay on anymore when the car is off so the battery isn't being drained. The bad news is it has never died while running before and it won't start even when jumped.
My buddy thinks it's a bad ECU, any ideas?
The good news is that the fuel pump does not stay on anymore when the car is off so the battery isn't being drained. The bad news is it has never died while running before and it won't start even when jumped.
My buddy thinks it's a bad ECU, any ideas?
So I thought I had fixed it but something new happened today. While I was driving, slowing down to a stop sign, the car died. It wasn't a loss of power, just a loss of fuel.
The good news is that the fuel pump does not stay on anymore when the car is off so the battery isn't being drained. The bad news is it has never died while running before and it won't start even when jumped.
My buddy thinks it's a bad ECU, any ideas?
The good news is that the fuel pump does not stay on anymore when the car is off so the battery isn't being drained. The bad news is it has never died while running before and it won't start even when jumped.
My buddy thinks it's a bad ECU, any ideas?
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