Fuel Pump Not Turning On
03-01-10, 06:28 PM
#16
you don't want to put a relay in there if its not working yet. your just adding complexity.
If its not working with the regular 12V mod, I can almost gaurantee you it will not work with the relay, cause the relay only turns on when the output from the fuel pump ecu is live.
you could run a relay off the ignition I suppose, but if your switched 12V line that supplies your fuel pump ecu isn't turning on, I doubt the fuel pump is the only issue your gonna see.
if you did the 12v mod without the relay, as in bypassing the fuel pump ecu by connecting the 12v wire and the fuel ecu output wire together, the pump should be on with the key in the accessory or on position, the engine does not need to be on/cranking. so put the key to on and test for voltage at the fuel pump ecu on the wires you soldered together. thats where I would start.
when did you do the 12v mod, before or after the 1jz install??
maybe you got the wrong wires...
If its not working with the regular 12V mod, I can almost gaurantee you it will not work with the relay, cause the relay only turns on when the output from the fuel pump ecu is live.
you could run a relay off the ignition I suppose, but if your switched 12V line that supplies your fuel pump ecu isn't turning on, I doubt the fuel pump is the only issue your gonna see.
if you did the 12v mod without the relay, as in bypassing the fuel pump ecu by connecting the 12v wire and the fuel ecu output wire together, the pump should be on with the key in the accessory or on position, the engine does not need to be on/cranking. so put the key to on and test for voltage at the fuel pump ecu on the wires you soldered together. thats where I would start.
when did you do the 12v mod, before or after the 1jz install??
maybe you got the wrong wires...
Last edited by Ali SC3; 03-01-10 at 06:46 PM.
03-03-10, 08:43 AM
#17
you don't want to put a relay in there if its not working yet. your just adding complexity.
If its not working with the regular 12V mod, I can almost gaurantee you it will not work with the relay, cause the relay only turns on when the output from the fuel pump ecu is live.
you could run a relay off the ignition I suppose, but if your switched 12V line that supplies your fuel pump ecu isn't turning on, I doubt the fuel pump is the only issue your gonna see.
if you did the 12v mod without the relay, as in bypassing the fuel pump ecu by connecting the 12v wire and the fuel ecu output wire together, the pump should be on with the key in the accessory or on position, the engine does not need to be on/cranking. so put the key to on and test for voltage at the fuel pump ecu on the wires you soldered together. thats where I would start.
when did you do the 12v mod, before or after the 1jz install??
maybe you got the wrong wires...
If its not working with the regular 12V mod, I can almost gaurantee you it will not work with the relay, cause the relay only turns on when the output from the fuel pump ecu is live.
you could run a relay off the ignition I suppose, but if your switched 12V line that supplies your fuel pump ecu isn't turning on, I doubt the fuel pump is the only issue your gonna see.
if you did the 12v mod without the relay, as in bypassing the fuel pump ecu by connecting the 12v wire and the fuel ecu output wire together, the pump should be on with the key in the accessory or on position, the engine does not need to be on/cranking. so put the key to on and test for voltage at the fuel pump ecu on the wires you soldered together. thats where I would start.
when did you do the 12v mod, before or after the 1jz install??
maybe you got the wrong wires...
Green w/ Silver Stripe
Silver
Black and red w/ silver stripe
Black and red( 12v mod)
Green(12v mod)
I definently did that correctly and I do need to test the ECU to see if it is getting full power. And I did the 12v mod during the 1J swap. The car turned on and ran perfectly before the swap was done.
So what now? I am getting 11.5-12v on all the other wires going into the fuel pump.
03-24-10, 10:21 AM
#24
theres a 12V wire that goes into your fuel ecu (lets call this input), and then theres an 9-12V wire that goes from the fuel ecu to the pump (lets call this output). I don't remember the colors.
If you don't have 12V at your input wire, something is very wrong.
You have to have the input wire connected to the fuel ecu for the output wire to work at all, so if you disconnected it (when you put your relay in) the output wire won't work.
if you take the input wire and connect it to the output wire and bypass the ecu, Thats the 12v mod and it gives your pump 12V when the key is on.
If you stick a relay in there using the input wire as a trigger, you still get the same exact operation out of your fuel pump as the 12V mod, and are unnecessarily complicating things.
If you leave the input wire connected to the fuel ecu, and use the output wire (9-12V) as a trigger to your relay, then you will have retained all the safety features of the fuel ecu without the dual voltage (because the relay always gives 12V when it detects an output on the output wire).
I would recommend going back to the basic 12V mod if you cannot diagnose the problem with the relay in the puzzle, it will be much easier like I suggested 23 days ago.. lol
I have a feeling you may have gotten the input and output wires mixed up. whichever one of the 2 thick wires that has 12V with the key on and engine off, will be the input wire. the output wire will not show any voltage unless the engine is on or the starter is engaged.
If you don't have 12V at your input wire, something is very wrong.
You have to have the input wire connected to the fuel ecu for the output wire to work at all, so if you disconnected it (when you put your relay in) the output wire won't work.
if you take the input wire and connect it to the output wire and bypass the ecu, Thats the 12v mod and it gives your pump 12V when the key is on.
If you stick a relay in there using the input wire as a trigger, you still get the same exact operation out of your fuel pump as the 12V mod, and are unnecessarily complicating things.
If you leave the input wire connected to the fuel ecu, and use the output wire (9-12V) as a trigger to your relay, then you will have retained all the safety features of the fuel ecu without the dual voltage (because the relay always gives 12V when it detects an output on the output wire).
I would recommend going back to the basic 12V mod if you cannot diagnose the problem with the relay in the puzzle, it will be much easier like I suggested 23 days ago.. lol
I have a feeling you may have gotten the input and output wires mixed up. whichever one of the 2 thick wires that has 12V with the key on and engine off, will be the input wire. the output wire will not show any voltage unless the engine is on or the starter is engaged.
Last edited by Ali SC3; 03-24-10 at 10:26 AM.
03-24-10, 10:39 AM
#25
theres a 12V wire that goes into your fuel ecu (lets call this input), and then theres an 9-12V wire that goes from the fuel ecu to the pump (lets call this output). I don't remember the colors.
If you don't have 12V at your input wire, something is very wrong.
You have to have the input wire connected to the fuel ecu for the output wire to work at all, so if you disconnected it (when you put your relay in) the output wire won't work.
if you take the input wire and connect it to the output wire and bypass the ecu, Thats the 12v mod and it gives your pump 12V when the key is on.
If you stick a relay in there using the input wire as a trigger, you still get the same exact operation out of your fuel pump as the 12V mod, and are unnecessarily complicating things.
If you leave the input wire connected to the fuel ecu, and use the output wire (9-12V) as a trigger to your relay, then you will have retained all the safety features of the fuel ecu without the dual voltage (because the relay always gives 12V when it detects an output on the output wire).
I would recommend going back to the basic 12V mod if you cannot diagnose the problem with the relay in the puzzle, it will be much easier like I suggested 23 days ago.. lol
I have a feeling you may have gotten the input and output wires mixed up. whichever one of the 2 thick wires that has 12V with the key on and engine off, will be the input wire. the output wire will not show any voltage unless the engine is on or the starter is engaged.
If you don't have 12V at your input wire, something is very wrong.
You have to have the input wire connected to the fuel ecu for the output wire to work at all, so if you disconnected it (when you put your relay in) the output wire won't work.
if you take the input wire and connect it to the output wire and bypass the ecu, Thats the 12v mod and it gives your pump 12V when the key is on.
If you stick a relay in there using the input wire as a trigger, you still get the same exact operation out of your fuel pump as the 12V mod, and are unnecessarily complicating things.
If you leave the input wire connected to the fuel ecu, and use the output wire (9-12V) as a trigger to your relay, then you will have retained all the safety features of the fuel ecu without the dual voltage (because the relay always gives 12V when it detects an output on the output wire).
I would recommend going back to the basic 12V mod if you cannot diagnose the problem with the relay in the puzzle, it will be much easier like I suggested 23 days ago.. lol
I have a feeling you may have gotten the input and output wires mixed up. whichever one of the 2 thick wires that has 12V with the key on and engine off, will be the input wire. the output wire will not show any voltage unless the engine is on or the starter is engaged.
03-24-10, 03:04 PM
#29
Ideally without that input wire connected to anything, you should verify it has 12V with the ignition on. if it does, do the 12v mod.
now if you mysteriously have no voltage in that line anymore, your pump is bad or wired incorrectly. its pretty much as simple as that.
now if you mysteriously have no voltage in that line anymore, your pump is bad or wired incorrectly. its pretty much as simple as that.
Thread
Thread Starter
Forum
Replies
Last Post
mrmcd982
SC- 1st Gen (1992-2000)
1
08-17-15 09:24 AM
1siksc
Performance & Maintenance
18
08-02-09 09:32 PM
