terribleturner Posted February 7, 2007 Share Posted February 7, 2007 Ha d a problem last week when i went out to the car. Fuel pumps were a no go. Checked all fuses and they were fine. Tapped and even removed EFI fuses. Removed Hanger with pumps and all fine. Totally stumped me. Have now found out that if you bridge the Diagnostic port the pumps start to run. Now my alarm/imobilser kills the pumps but seems to be turning off when commanaded to. Could it possibly be were i've done my 12v mod?? If there was a problem there would the pumps run when bridging the port?? Any other ideas?? Link to comment Share on other sites More sharing options...
terribleturner Posted February 8, 2007 Author Share Posted February 8, 2007 Bump anyone?? Link to comment Share on other sites More sharing options...
SimonB Posted February 8, 2007 Share Posted February 8, 2007 Could be I guess. Bridging the diagnostic port runs them at 12V whereas the ECU might use 9V when cranking. I thought it used 12V while cranking but I can't remember now. Not sure what you could have done that would make them not work at 9V though! Link to comment Share on other sites More sharing options...
Supra ST Myster Posted February 8, 2007 Share Posted February 8, 2007 have you checked to see if the relay is ok for the 12V mod and is actually changing state when voltage is applied, may be a bad connection here Link to comment Share on other sites More sharing options...
terribleturner Posted February 8, 2007 Author Share Posted February 8, 2007 Emin i don't think i have a relay in the 12v mod tbh. Link to comment Share on other sites More sharing options...
absz Posted February 8, 2007 Share Posted February 8, 2007 Could be I guess. Bridging the diagnostic port runs them at 12V whereas the ECU might use 9V when cranking. I thought it used 12V while cranking but I can't remember now. Not sure what you could have done that would make them not work at 9V though! same theory no feed to ecu but bridging diagnostic port is back feeding which provides the feed to ecu Link to comment Share on other sites More sharing options...
terribleturner Posted February 8, 2007 Author Share Posted February 8, 2007 So the pumps get the earth and power from the ecu?? Isn't there some sort of pump ecu if memory serves. Link to comment Share on other sites More sharing options...
Supra ST Myster Posted February 8, 2007 Share Posted February 8, 2007 oh right, so how is it done then on your car? Link to comment Share on other sites More sharing options...
terribleturner Posted February 8, 2007 Author Share Posted February 8, 2007 Im thinking it's 2 wires from the pump ecu/control box are just twisted together. Can't actuaally remeber tbh and the cars not here to look at. Link to comment Share on other sites More sharing options...
Supra ST Myster Posted February 8, 2007 Share Posted February 8, 2007 9V is switched to the pump ecu and normally the 12V mod is there, uses that 9V to make a relay come on with a hard 12V on its contact and thus supplying the 12V to the pumps, the ecu is tucked into the rear quater panel passenger side, bitch to get to.. Link to comment Share on other sites More sharing options...
terribleturner Posted February 8, 2007 Author Share Posted February 8, 2007 Think i need to get in there and have a look. Link to comment Share on other sites More sharing options...
Supra ST Myster Posted February 8, 2007 Share Posted February 8, 2007 i do have the instructions for the 12V mod as use to supply the relays in a potted small box, and im pretty sure you cut the 9V and car ecu end you supply to new relay and the other side of the cut wire is where the 12V switches onto... Link to comment Share on other sites More sharing options...
absz Posted February 8, 2007 Share Posted February 8, 2007 theres one in the nearside inner qauter panel which is normally by passed when the 12volt mod is done. there should be a ignition feed to the ecu, the ecu then supplys the feed to efi relays/pump Link to comment Share on other sites More sharing options...
terribleturner Posted February 8, 2007 Author Share Posted February 8, 2007 If i said the pumps started to run as soon as the ignition was turned on, would that give any clues to how the mod was done?? Link to comment Share on other sites More sharing options...
Supra ST Myster Posted February 8, 2007 Share Posted February 8, 2007 no as the mod is basically affective when the normal 9v is supplied. Link to comment Share on other sites More sharing options...
absz Posted February 8, 2007 Share Posted February 8, 2007 If i said the pumps started to run as soon as the ignition was turned on, would that give any clues to how the mod was done?? from memory there is already a constant 12volts supply but the fuel pump ecu drops it to 9volts. by removing the fuel pump ecu and wiring the wires which are 12volts straight to pump does the job. but will keep running the pump as long as the ignition is on, even if engine is not running. Link to comment Share on other sites More sharing options...
Supra ST Myster Posted February 8, 2007 Share Posted February 8, 2007 the ecu changes the 9v to 12v when you boot it.. and that is sepearte to the constant 12V that is also supplied to the ECU, i think that is used just to power the ecu Link to comment Share on other sites More sharing options...
bondango Posted February 8, 2007 Share Posted February 8, 2007 Ha d a problem last week when i went out to the car. Fuel pumps were a no go. Checked all fuses and they were fine. Tapped and even removed EFI fuses. Removed Hanger with pumps and all fine. Totally stumped me. Have now found out that if you bridge the Diagnostic port the pumps start to run. Now my alarm/imobilser kills the pumps but seems to be turning off when commanaded to. Could it possibly be were i've done my 12v mod?? If there was a problem there would the pumps run when bridging the port?? Any other ideas?? IF you bridge FP and B+ and the pumps run, then the fault is with the Relay. As with the diagnostic mode your basically supplying power straight to the Fuel pump ECU ...Of the top of me head thats EFI No.2 relay, worth checking it, and also the main EFI relay, as i think they share the circuit. Link to comment Share on other sites More sharing options...
terribleturner Posted February 8, 2007 Author Share Posted February 8, 2007 IF you bridge FP and B+ and the pumps run, then the fault is with the Relay. As with the diagnostic mode your basically supplying power straight to the Fuel pump ECU ...Of the top of me head thats EFI No.2 relay, worth checking it, and also the main EFI relay, as i think they share the circuit. Hhmm i think the relay has been swoped for a working one with no joy. But i will double check to see Link to comment Share on other sites More sharing options...
bondango Posted February 8, 2007 Share Posted February 8, 2007 Hhmm i think the relay has been swoped for a working one with no joy. But i will double check to see I'l go through the Wiring diagram in work tomorrow matey, and list the main culprits, but the 2 efi fuses and 2 relays are always my 1st port of call if the Diagnostic bridge gets the pumps going. Link to comment Share on other sites More sharing options...
terribleturner Posted February 8, 2007 Author Share Posted February 8, 2007 Nice one cheers mate. Link to comment Share on other sites More sharing options...
Ian C Posted February 8, 2007 Share Posted February 8, 2007 Are you saying that the fuel pump fires up as soon as the ignition goes on? Gah, another unsafe 12v mod If you bin it the pump will carry on pumping until you key off. If you can. As this is the cheapest and nastiest way to do the 12v mod, I immediately suspect it's wiring -Ian PS oh and what's your reasoning for having a 12v mod? I suspect a reversion back to stock might be a great way to fix this problem... Link to comment Share on other sites More sharing options...
SimonB Posted February 8, 2007 Share Posted February 8, 2007 If i said the pumps started to run as soon as the ignition was turned on, would that give any clues to how the mod was done?? Actually yes, because normally the ECU doesn't run the fuel pump until you crank the engine - it doesn't run it just on ignition on. The fuel pump ECU has a 12V supply which is on when the ignition is, a wire from the ECU which it sets to 12V or 9V but only when the engine is cranking or running and an output to the pump. Sounds like your 12v mod was to join the 12V supply to the pump output. That will make your pump see 12v all the time the ignition is on. Not a great idea, as it will keep running the pump even if you're upside down in a ditch and the engine has stopped! Link to comment Share on other sites More sharing options...
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