Quinten Posted February 28, 2015 Share Posted February 28, 2015 Having done another test it all seems to work ok, but now the car wont stop running! Even shutting the battery cut off, the alternator keeps it going... How can I safely shut it down?!?! Pull the fuel pump power? Quote Link to comment Share on other sites More sharing options...
TAFKARM Posted February 28, 2015 Share Posted February 28, 2015 Disconnect the fuel pump Quote Link to comment Share on other sites More sharing options...
Stuart Posted February 28, 2015 Share Posted February 28, 2015 Hand over air inlet? Quote Link to comment Share on other sites More sharing options...
daggartuk Posted February 28, 2015 Share Posted February 28, 2015 This happened to me once - engine kept on running after changing the ignition light bulb! Oddly enough, pressing the washer wiper switch knocked the engine off. Weird! Quote Link to comment Share on other sites More sharing options...
Dave Eastwood (Gadgetman) - Club Chairman Posted February 28, 2015 Share Posted February 28, 2015 Having done another test it all seems to work ok, but now the car wont stop running! Even shutting the battery cut off, the alternator keeps it going... How can I safely shut it down?!?! Pull the fuel pump power? If you've got an engine cut off, then once you've stopped the engine, (fuel pump fuse is a good one, as is ecu fuse etc) you need to check the cut out's wiring, 'cause somethings wrong. A proper cut out should dump the alternators current - and any supplied by spinning, freewheeling motors, like cooling fans, to ground, which will help stop the run on. On the other hand, if it's just a battery isolator, not a proper cut out (FIA), then I'm afraid they will do what you say. Worse still, you can get a spike of current that can damage the ecu, if a battery isolator is turned off with the engine running. Quote Link to comment Share on other sites More sharing options...
Quinten Posted February 28, 2015 Author Share Posted February 28, 2015 Panic over, disconnecting the fuel pump killed it eventually. Obviously I need to find out what is wrong with the cut-off, but christ, that was scary Quote Link to comment Share on other sites More sharing options...
Mark (smokey mow) Posted February 28, 2015 Share Posted February 28, 2015 Panic over, disconnecting the fuel pump killed it eventually. Obviously I need to find out what is wrong with the cut-off, but christ, that was scary If you've got an engine cut off, then once you've stopped the engine, (fuel pump fuse is a good one, as is ecu fuse etc) you need to check the cut out's wiring, 'cause somethings wrong. A proper cut out should dump the alternators current - and any supplied by spinning, freewheeling motors, like cooling fans, to ground, which will help stop the run on. I'm guessing you haven't yet got around to correctly rewiring the battery cut-off switch to the positive side yet? http://forum.wscc.co.uk/forum/index.php/topic/112585-relocating-battery-cut-off-switch-or/ 1 Quote Link to comment Share on other sites More sharing options...
Dave Eastwood (Gadgetman) - Club Chairman Posted February 28, 2015 Share Posted February 28, 2015 Is the cut off you're only method of turning off now? If not, why didn't it turn off with the ignition? Again, it's not unknown for car's with older style wiring to be kept running by back current from the rad fan. Basically, when the rad fan is not controlled by a relay, when its spinning and you turn off the ignition, momentum keeps it turning, which causes it's motor to act like a dynamo and generate a little current. Without a relay, this feeds straight into the wiring and can be enough to keep the ecu relays closed, which keeps the engine running. Although the ignition being off has cut the battery, the alternator keeps the engine going. Quote Link to comment Share on other sites More sharing options...
Dave Eastwood (Gadgetman) - Club Chairman Posted February 28, 2015 Share Posted February 28, 2015 This happened to me once - engine kept on running after changing the ignition light bulb! Oddly enough, pressing the washer wiper switch knocked the engine off. Weird! That's cause the wiper motor pulled enough current to use up what ever "rogue current" was keeping the ecu powered. (Or relays supplying ign feed). Quote Link to comment Share on other sites More sharing options...
daggartuk Posted February 28, 2015 Share Posted February 28, 2015 Thanks Dave, your last two posts explain perfectly what was going on. 1 Quote Link to comment Share on other sites More sharing options...
TableLeg Posted February 28, 2015 Share Posted February 28, 2015 If using the FIA type master switch it is often a good idea to have any ignition/coil power feed via the switch secondary terminals. That way isolation with the switch will kill the power to ignition/coil/coils killing the engine. Quote Link to comment Share on other sites More sharing options...
Quinten Posted February 28, 2015 Author Share Posted February 28, 2015 Right, first I want to thank you all for your helpful comments. I haven't relocated the battery cut off switch yet, so this is still connected as before on the negative side, preventing all ground/chassis connections to go back to the negative terminal. This is why I am so confused, as I thought with nothing going to negative, the alternator couldn't keep on going... After I killed the fuel pump, the engine stalled and then I went and did my planned oil change. Once finished, I tried it again and when the engine was cold, it would stop by turning the ignition key off again. So far so good I thought, but after I started the car again and let it warm up (needed to make sure the fan was going to run on the temperature/fan switch) the ignition key would no longer stop the engine running. I'll draw up a diagram of the connections that I think matter to this, and hopefully using the collective I can get it sorted. Quote Link to comment Share on other sites More sharing options...
CraigHew Posted February 28, 2015 Share Posted February 28, 2015 Many years ago I had a similar problem on my old Cortina (in that the engine wouldn't stop). I found that holding a suitable rag / blockage up the end of the exhaust killed things pretty quickly without pulling (potentially volatile) hoses and stuff off. Clearly not a long term solution but simple to do in a panic situation. Quote Link to comment Share on other sites More sharing options...
Terry Everall Posted February 28, 2015 Share Posted February 28, 2015 Why is the cut off with working/connected to the negative That is not how an FIA cut off switch works Google a diagram or maybe someone will post one here 1 Quote Link to comment Share on other sites More sharing options...
TableLeg Posted February 28, 2015 Share Posted February 28, 2015 http://www.locostbuilders.co.uk/gallery/fiamaster.jpg Quote Link to comment Share on other sites More sharing options...
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