alex park Posted December 4, 2007 Share Posted December 4, 2007 Hi Guys n Gals. Once again my97 3.9 v8 Disco has decided to dig me in the ribs and refuse to start. It turns over fine, (brand new battery showing 12.8v and 14.2 when charging) fuel relay working (can hear and feel it clicking) Fuel pump working (can hear it whirring away in the tank) (spider previously stomped all over and bypassed) the ignition isolator isnt tripped 12v at the coil initially it will turned over and make out as if it wants to start ie fire just enough that you think it might want to start but nothing happens. can anyone gve me any hints as to where to start looking. I have thought maybe the coil is packed up it's bags?? Thanks Alex Quote Link to comment Share on other sites More sharing options...
BogMonster Posted December 4, 2007 Share Posted December 4, 2007 I may be wrong but somewhere in the dark recesses of my mind something is whispering to me that the coil always has 12V and it is the earth side of it that is switched to make the spark, so I would check that side of the circuit and make sure the dizzy/ignition amplifier is all OK. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted December 4, 2007 Share Posted December 4, 2007 He's right - the coil gets +12v from ignition switched live and the amp grounds the -ve side. Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted December 4, 2007 Share Posted December 4, 2007 Injectors firing? You can normally hear them as a faint clicking as you spin the engine over... Quote Link to comment Share on other sites More sharing options...
alex park Posted December 4, 2007 Author Share Posted December 4, 2007 i couldnt hear the injectors firing when it was turning over. Alex Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted December 4, 2007 Share Posted December 4, 2007 Next step - have you got a spark? The firing of the coil triggers the ECU to fire the injectors, no spark = no fuel. Obviously also no spark=no go anyway Quote Link to comment Share on other sites More sharing options...
alex park Posted December 4, 2007 Author Share Posted December 4, 2007 does begin to sound like the coil is the culprit, it will have to wait till tomorrow afternoon now, its dark and the wolves are howling.... and i'm on nights, thanks Alex Quote Link to comment Share on other sites More sharing options...
T1G UP Posted December 4, 2007 Share Posted December 4, 2007 Mates 3.9 RR doesn't want to start. He's discovered its the Dizzy, the shaft has play and the spark ain't jumping across regularly. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted December 4, 2007 Share Posted December 4, 2007 Could be a dead coil or dodgy dizzy, most common cuplrit for failure is the ignition amp. Quote Link to comment Share on other sites More sharing options...
alex park Posted December 5, 2007 Author Share Posted December 5, 2007 are amplifiers directly replaceable? or is it full dizzy? just checked the dizzy cap and it looked like theres lots of tracking marks. I dont think it o/e cap either. Alex Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted December 5, 2007 Share Posted December 5, 2007 Do genuine plugs, leads, cap, rotor since it seems questionable - if it still don't work then yes you can change the amp, if it's on the side of the dizzy I think they're about £36. Quote Link to comment Share on other sites More sharing options...
BogMonster Posted December 5, 2007 Share Posted December 5, 2007 On a Discovery of that age it will be a remote amp, bolted to the inside of the bonnet slam panel right next to the coil. Not sure about the prices. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted December 5, 2007 Share Posted December 5, 2007 They're about £eeek, do this instead. Quote Link to comment Share on other sites More sharing options...
alex park Posted December 13, 2007 Author Share Posted December 13, 2007 new o/e dizzy cap and cleaned up the old rotor arm as it was stuck, and i know if i pull it the wights and springs will go pop. roared into life good as gold. cheers all once again. Alex Quote Link to comment Share on other sites More sharing options...
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