6a turns over, fires up and stops when key is let go

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6a turns over, fires up and stops when key is let go

Post by Masterblaster » Sat May 23, 2020 10:26 am

Hi yes, and just found out after cranking theres only live one side of ballast resistor



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6a turns over, fires up and stops when key is let go

Post by philhoward » Sat May 23, 2020 10:43 am

No volts or only a few volts? Are you measuring with a test bulb or a meter?


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6a turns over, fires up and stops when key is let go

Post by Masterblaster » Sat May 23, 2020 11:02 am

At ignition live side of ballast resistor ive got, 12.4v nothing at other side



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6a turns over, fires up and stops when key is let go

Post by scimjim » Sat May 23, 2020 11:18 am

Bypass the ballast to confirm then.


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6a turns over, fires up and stops when key is let go

Post by willholderogri » Sat May 23, 2020 12:17 pm

Balast open circuit


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6a turns over, fires up and stops when key is let go

Post by AJL Electronics » Sat May 23, 2020 12:23 pm

Why are you so determined not to follow the advice to hotwire it?


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6a turns over, fires up and stops when key is let go

Post by Masterblaster » Sat May 23, 2020 1:42 pm

Hi, doesn't hotwiring just bypass key, i already have 12v from key to ballast resistor, or am i barking up the wrong tree, also ballast resistor bypassed but no difference



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6a turns over, fires up and stops when key is let go

Post by rebel alliance » Sat May 23, 2020 2:00 pm

Why don't you do it and see what happens if it runs off the starter supplied power then it should run if you hotwire it as said its probably the ignition switch



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6a turns over, fires up and stops when key is let go

Post by AJL Electronics » Sat May 23, 2020 2:08 pm

The whole point of hotwiring is to bypass all the components in that circuit. It narrows down the fault. Just do it and see what happens. It is a standard step in ignition fault finding.


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6a turns over, fires up and stops when key is let go

Post by Masterblaster » Sat May 23, 2020 2:48 pm

Ok it goes when hotwired, confused me though



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6a turns over, fires up and stops when key is let go

Post by rebel alliance » Sat May 23, 2020 3:30 pm

So change the electrical part of the ign switch it may be that



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6a turns over, fires up and stops when key is let go

Post by scimjim » Sat May 23, 2020 6:06 pm

Masterblaster wrote:
Sat May 23, 2020 2:48 pm
Ok it goes when hotwired, confused me though
so it’s either the switch, or the wiring between the switch and ballast. Switch is the simplest thing to change first.


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6a turns over, fires up and stops when key is let go

Post by Old and Slow » Sat May 23, 2020 10:19 pm

Just because you have 12v on the coil side of the ballast resistor it doesn't mean there isn't a fault (you aren't drawing any current so there's no volt drop in the circuit). If the ignition feed path has a connector with "high" resistance then it will drop the voltage and there won't be enough current flowing into the coil after the "starting phase".
Here's what I suggest:
Put an earth wire on the contact breaker side of the coil so that current can flow continuously through the ignition circuit, and then turn the ignition on (but not as far at spinning the starter) and measure the voltage across the coil. If it is less that 8v there's a high resistance in circuit somewhere. Jiggle the ignition key a bit whilst watching the voltmeter and see if it fluctuates - i.e. a dodgy switch.
It could be the tachometer if it is the type that has the ignition feed running through it - a beefy white wire. The bullets at the tacho are a male/female in/out so you can unplug them from the tacho and plug them together to bypass the tacho and the ignition should still work (unless it is one of the bullets that is high resistance).
Hope this helps.
Philip


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6a turns over, fires up and stops when key is let go

Post by philhoward » Sun May 24, 2020 2:02 am

This doesn’t use that type of tacho, Philip.

It is a little confusing as separate tests have given 12v both sides of the ballast resistor and only one side. Could be one of those ballast failures where it’s just touching (the wire itself) but as soon as there’s any current draw or vibration it goes open circuit?


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