istruggle2gate11 Posted August 12, 2006 Share Posted August 12, 2006 Hi all, Im installing an LPG system into a 1989 Rangie with 3.5 Flapper injection. Its second hand but never fitted system, all parts are there but unfortunately I cant rely on Tinley Tech for support as the system was bought new 3 years ago. All the hardware has installed fine, Ive come to the wiring up part now, and have hit a cross roads... The kit comes with a switch and relay which when wired up to the rev counter signal it turns off the injectors and activates the gas control solenoid/valve. According to the wiring instructions, I only need to intercept the wire from the injector relay. This would then leave power to the ECU and fuel pump (I know some gas systems leave the fuel pump running but I would rather just turn it off). I would much prefer to use the LPG/Petrol switch to turn off the ECU complety, which in turn would cut the injectors and fuel pump. Is this plan flawed? I assume that the old flapper type ignition doesnt require the ecu to be powered? Im not bothered about "clean" switching, worst case, I start on petrol then restart on LPG when the engine is warm enough. Ta Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted August 12, 2006 Share Posted August 12, 2006 Is it a venturi or injected LPG kit? If it's a venturi one, be very wary of starting on gas, particularly with a flapper air flow meter - they tend to backfire and wreck the AFM... Cutting the power supply for too long will result in the ECU resetting to its default fuelling map then having to go into coarse tuning mode next time you use it. Mine leaves the fuel pump running - just disconnects the injectors and fakes their presence to the ECU. Works fine - the pump would be running anyway if you were running on petrol. You could have a play if you want, see what you can come up with - as long as you wire everything right I can't see how you could do any permanent damage - but it certainly isn't necessary. Quote Link to comment Share on other sites More sharing options...
Bull Bar Cowboy Posted August 12, 2006 Share Posted August 12, 2006 Rog, You need to run the pump so that fuel circulates through the fuel rail thus cooling the injectors ……… otherwise the injectors become toast in a very short time frame. Its faily easy to do a mod to shut down the ECU and run the pump. Ian Quote Link to comment Share on other sites More sharing options...
istruggle2gate11 Posted August 13, 2006 Author Share Posted August 13, 2006 Is it a venturi or injected LPG kit? If it's a venturi one, be very wary of starting on gas, particularly with a flapper air flow meter - they tend to backfire and wreck the AFM...Cutting the power supply for too long will result in the ECU resetting to its default fuelling map then having to go into coarse tuning mode next time you use it. Mine leaves the fuel pump running - just disconnects the injectors and fakes their presence to the ECU. Works fine - the pump would be running anyway if you were running on petrol. You could have a play if you want, see what you can come up with - as long as you wire everything right I can't see how you could do any permanent damage - but it certainly isn't necessary. Hi Geoff, yes its a Venturi, with a nasty looking "anit backfire" device, which I wont put much faith in! Mine disconnects the injectors through a relay but doesnt emmulate them, I guess the ecu doesnt read that info? Ive got no Lambda sensors etc. Rog,You need to run the pump so that fuel circulates through the fuel rail thus cooling the injectors ……… otherwise the injectors become toast in a very short time frame. Ian Hi Ian, Thats the answer that nobody was giving me, I really couldnt understand why the "factory" method left the pump running. Thanks guys, with the above in mind I will wire as per instructions, so that even in gas mode it starts on petrol then switches over to gas when the throttle is blipped to 1500rpm. Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted August 13, 2006 Share Posted August 13, 2006 Mine disconnects the injectors through a relay but doesnt emmulate them, I guess the ecu doesnt read that info? Ive got no Lambda sensors etc. Maybe the flapper system doesn't monitor the injectors? Mine's a hotwire. Quote Link to comment Share on other sites More sharing options...
Bull Bar Cowboy Posted August 13, 2006 Share Posted August 13, 2006 Mine disconnects the injectors through a relay but doesnt emmulate them, I guess the ecu doesnt read that info? Ive got no Lambda sensors etc. Rog, The 14CU flapper just sends a ‘open for x amount of time’ pulse to the injector bank …………the lenghth of which depends upon which part of the fuel map it is in …………. It does no checks to actually ensure that the injectors have opened Ian Quote Link to comment Share on other sites More sharing options...
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