Dragonball Posted June 15, 2003 Share Posted June 15, 2003 Even I can do it- LOL! hasn't been mentioned in a while so thought might just bring it to the fore. For those who may not know (and please correct me if I am incorrect) - the stock fuel pump ECU puts out 9V to the pump until heavy load required - when it then boosts it to 12V. This mod just turns the signal to a constant 12V - therefore helping reduce possibility of pump not keeping up with higher boost between 4000 and 5000revs Instructions on mkiv.net And have to say feel a real difference in low down pick-up - and boosted to 1.26 (blowing away a lotus esprit this afternoon) with better EGT's than experiencing to date! Std Fuel / Boost diff has changed to 3.2 from 3.0 Recommended and so siimple! Link to comment Share on other sites More sharing options...
400BHP Posted June 15, 2003 Share Posted June 15, 2003 Will try that Paul and will report back. (when bumper finally back on) Link to comment Share on other sites More sharing options...
Geezabloke Posted June 15, 2003 Share Posted June 15, 2003 Paul do you have more details and is it relevant for UK specs too? Link to comment Share on other sites More sharing options...
400BHP Posted June 15, 2003 Share Posted June 15, 2003 12v Fuel Pump Mod Link to comment Share on other sites More sharing options...
Bobbeh Posted June 15, 2003 Share Posted June 15, 2003 Just a word of warning, mkiv.net opened up a load of pr0n sites for me.. be careful the url is correct next time plz. Link to comment Share on other sites More sharing options...
Justin Posted June 15, 2003 Share Posted June 15, 2003 Hmmmmm. Interesting. I might go for that. Pull away and low revs definitely could do with boosting I reckon. Easy job Paul was it? Any things to look out for? J. Link to comment Share on other sites More sharing options...
400BHP Posted June 15, 2003 Share Posted June 15, 2003 I found that hence the link Chris:flame Dev Link to comment Share on other sites More sharing options...
Bobbeh Posted June 15, 2003 Share Posted June 15, 2003 Thats better, I guess Paul E is too lazy, either that or swamped in unsold Neons! Link to comment Share on other sites More sharing options...
Geezabloke Posted June 15, 2003 Share Posted June 15, 2003 Cheers 400, have you tried and tested this as well as Paul? If so did you notice a difference, bearing in mind the UK's already have bigger injectors and may not suffer as much from fuel starvation? Link to comment Share on other sites More sharing options...
Paul R Posted June 15, 2003 Share Posted June 15, 2003 Have you noticed any difference in fuel economy after the mod? I'm after things like this to try on my car when I pick it up.....but if it affects fueld economy too much then I'll have to wait til my re-mortgate comes through So many things I want to do! so much money needed! So much house and so little mortgage!! Paul Link to comment Share on other sites More sharing options...
Guest Martin F Posted June 15, 2003 Share Posted June 15, 2003 There is no point doing this mod until you are at least BPU. It shouldn't really make much difference to low down pick-up if your fuel system is running OK. It was produced to overcome the lean spot for BPU cars when the second turbo came on boost. Link to comment Share on other sites More sharing options...
Dragonball Posted June 15, 2003 Author Share Posted June 15, 2003 Originally posted by Justin Hmmmmm. Interesting. I might go for that. Pull away and low revs definitely could do with boosting I reckon. Easy job Paul was it? Any things to look out for? J. Very easy - 10 minute job Not sure how much will improve UK spec - larger injectors and all Link to comment Share on other sites More sharing options...
Nathan Posted June 16, 2003 Share Posted June 16, 2003 Originally posted by Martin F There is no point doing this mod until you are at least BPU. It shouldn't really make much difference to low down pick-up if your fuel system is running OK. It was produced to overcome the lean spot for BPU cars when the second turbo came on boost. Agreed. In fact, I think it's a pointless exercise on any car IMO, and if gains are seen then the system had faults to start with. We DO convert to 12v when we use uprated pumps but then thats only because any decent pump needs 12v to actually run. In addition, if anyone really does want to carry out a 12v mod then I advise you to run a relay as well. Most 12v conversions make the pump live all the time the ignition is on, not ideal if you're upside down wedged in your car after a smash with fuel being dowsed over you and the car at 3 bar..... Regards, Nathan TDI PLC Link to comment Share on other sites More sharing options...
400BHP Posted June 16, 2003 Share Posted June 16, 2003 Originally posted by Nathan Agreed. In fact, I think it's a pointless exercise on any car IMO, and if gains are seen then the system had faults to start with. We DO convert to 12v when we use uprated pumps but then thats only because any decent pump needs 12v to actually run. In addition, if anyone really does want to carry out a 12v mod then I advise you to run a relay as well. Most 12v conversions make the pump live all the time the ignition is on, not ideal if you're upside down wedged in your car after a smash with fuel being dowsed over you and the car at 3 bar..... Regards, Nathan TDI PLC I concur, you can use a relay and utilise the fuel pump output from the fuel pump ecu to switch the 12v into the pump, there is an inertia cut-out in the ecu to stop the fuel pump supply in the event of a crash, which will not happen if you wire it to a permanent live. if you want a schematic I will draw you one. The degree in electrical engineering was worth something then! Link to comment Share on other sites More sharing options...
richardharmon Posted June 16, 2003 Share Posted June 16, 2003 I assume if one wanted to carry out this mod then a solution would be to connect the fuel pump to the 12v power supply via a relay, then wire the relay coil to the old fuel pump power source. Don’t know what the driver circuit is like from the fuel pump ECU so it might also be worth putting a reverse biased diode across the relay coil to prevent nasty back EMF spikes when the pump is switched off. What current does the pump draw in 12v mode? Link to comment Share on other sites More sharing options...
Nathan Posted June 16, 2003 Share Posted June 16, 2003 Richard, Yep, thats what 400bhp said I believe...... The Walbro pumps draw 10A @ 4.5 bar, which is slightly less than the stock Jap pump. Regards, Nathan TDI PLC Link to comment Share on other sites More sharing options...
richardharmon Posted June 16, 2003 Share Posted June 16, 2003 Indeed, just adding my 2p Link to comment Share on other sites More sharing options...
Guest Martin F Posted June 16, 2003 Share Posted June 16, 2003 Originally posted by richardharmon Don’t know what the driver circuit is like from the fuel pump ECU so it might also be worth putting a reverse biased diode across the relay coil to prevent nasty back EMF spikes when the pump is switched off. What current does the pump draw in 12v mode? Don't think that will be a big issue for a driver circuit that has been running a nice noisy pump. Link to comment Share on other sites More sharing options...
richardharmon Posted June 16, 2003 Share Posted June 16, 2003 Originally posted by Martin F Don't think that will be a big issue for a driver circuit that has been running a nice noisy pump. I think you're right. Still, thought it was worth mentioning as a general point. Link to comment Share on other sites More sharing options...
400BHP Posted June 16, 2003 Share Posted June 16, 2003 Originally posted by richardharmon I assume if one wanted to carry out this mod then a solution would be to connect the fuel pump to the 12v power supply via a relay, then wire the relay coil to the old fuel pump power source. Don’t know what the driver circuit is like from the fuel pump ECU so it might also be worth putting a reverse biased diode across the relay coil to prevent nasty back EMF spikes when the pump is switched off. What current does the pump draw in 12v mode? No need, the 12v supply you are using is the one that already supplies the pump, albeit you are re-routing it. I dont think Electromotive Force feedback will be much of an issue with 12volts.... Link to comment Share on other sites More sharing options...
Dragonball Posted June 16, 2003 Author Share Posted June 16, 2003 Oh gawd- the techies have hijacked the thread:eek: Then theres the doom-laden lot (not to be confused with the bin-laden lot) - hey guys if one is upside down with petrol pouring out there's about 900 other places that a spark is gonna come from to fry ones arse !!! Just wanted to give people the opportunity of sharing in my tidings! Will be getting the UK spec pump sitting in my garage fitted (cos I don't do DIY when it comes to the wet stuff!) but the EGT's have definately reduced ! Link to comment Share on other sites More sharing options...
Nathan Posted June 17, 2003 Share Posted June 17, 2003 Paul, We're not trying to be doom and gloom at all chap, and I think you've got the 'spark' thing wrong. The point of the relay is that on the stock car the pump only runs when the engine is running. With your 12v mod, the pump is running all the time, whether the engine is or not. So, in the event of a nasty stack, you will be pumping fuel until a: the fuel tank is empty or b: you can turn the ignition off (not the first thing on your mind if you are unconscious). A situation not to be taken lightly IMO but if you call that doom-mongering then so be it. For the sake of a 6 quid relay and 10 more minutes the issue is dealt with. Cheers, Nathan TDI PLC Link to comment Share on other sites More sharing options...
400BHP Posted June 17, 2003 Share Posted June 17, 2003 Yep, thats the point I was trying to relay. There is an inertia switch on these modern systems, comprising of, believe it or not, a magnet and a ball bearing! At a certain inertial force being reached the ball bearing comes away from the magnet and drops down disconnecting the circuit. Other types include relays that sense engine revolutions etc etc and these are more complicated, I'm not sure what type is fitted to the Supra, More than likely the engine sensing type due to lack of a reset switch that would be essential in the case of the inertia type. Either way, all Nathan and I are trying to convey with the least possible condesending manner is that, if you get any sort of problem with your fuel system, beit a fuel pipe split, failure in a fuel carrying component or worst case scenario a crash (god help us all) whenever the ignition is on, the pump will be running. The pump may be ok to run for 2 seconds or so before cranking to prime the fuel rail but for the pump to run outside of this time is dangerous, which is what will happen if the relay is not used. I personally think the artice on MKIV.com should be amended, because it states that this mod is safe because the pump is fused. This is not strictly true as we have highlighted! At the end of the day its up to you, there are no regulations about tampering with your car except those imposed by your insurance company and the construction and use of road vehicles...blah blah blah. I just think if you really care about your car you will take that extra bit more time to do it right... right? Link to comment Share on other sites More sharing options...
Dragonball Posted June 17, 2003 Author Share Posted June 17, 2003 No disagreement from me lads - sounds well thought out- just how does this 'relay' fit and where can I get it from? Also - if you were modifying the instructions could you add how to fit a relay etc for everyone please? Cheers paul Link to comment Share on other sites More sharing options...
400BHP Posted June 17, 2003 Share Posted June 17, 2003 To relay or not to relay? Link to comment Share on other sites More sharing options...
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