Thats strange ...

Hi all . my 40 is almost complete now . been doing final testing of stuff as you do ... Just making sure all is good .... ready for IVA all has been good engine starting and running up nice ..... all lighting good .... body catches ..... fans ... BUT to day I was in the garage tinkering and a strange thing is now happening .. when I turn the ignition key to 1st click ready to press the start button ... and the engine spins over without stopping before I have pressed the start button ....... Do you think it could be a dodgy ignition switch ... Its been fine since the loom and gauges have been fitted .. I just don't understand this ........ Any ideas guys and girls ..

Many years ago when doing engine swaps we found on English cars that the alt warning light did not have enough resistance to trigger the alt to charge when used with USA type alternators with the result that engine would continue to run after ign turned off or kill switch turned off, a small resistor in parallel with warning light or a larger wattage bulb if space allowed was enough to fix it, But your problem might be in the starter button- stuck contacts. As long as battery is connected the starter will engage as soon as power reachs solenoid, work back from that. Also make sure solenoid terminal is not touching live main lead or terminal to starter.

Swap PC to edit this... Ive apparently got an issue with wires running too close to one another on it!!.. The resistor was reqd to make USA Autolite/Motorcraft Alt work with UK Frd wiring looms, Randy is correct, a diode was reqd to prevent run on with USA Alt/UK car wiring on key off or master off. Track safety guys get a bit upset when they hit the kill switch and the engine keeps reving its head/s off!!
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Randy V

Staff member
Lifetime Supporter
Are you sure that wasn't a diode Jac?

Disconnect the positive wire from the alternator and then the energizing wire (small primary) from the starter solenoid just and check for 12v there when you click the switch to RUN position. If it is 12v, I would suspect the ignition switch.

Ian Anderson

Lifetime Supporter
Are you running a coil that needs a ballast resistor in normal running? Runs about 9 volts and then has a direct feed from starter during cranking to give a better spark to start?

If connected to wrong terminal on the starter the bypass wire can back feed and energise the starter solenoid.

Thank you guys you are all great.....Ian no ballast resister fitted m8 ....Jac and Randy will give it a look a bit later today .....
Thank you again John..
Hi John,
I would be looking for stuck contacts in your starter switch. As I don’t believe you’ve a relay on the starter to solenoid line, it could have fused the contacts, especially if it’s a reproduction one
Hi Andy m8 hope you are well .. I did think the same . I am going to disconnect the starter button over the weekend . See what happens . Will let you know how it goes ...
Thanks for your reply m8 ..

Hi John,
Glad you found the route cause of the issue. Wire in a relay so you don't get a repeat failure, even if you get one with a higher current rating.