GT Won't start

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saintjamesy89
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Re: GT Won't start

Post by saintjamesy89 »

I had considered the wiring too Mat, the spade connectors and leads that go from the ignition module to the four spade receptors on top of the coil are quite tatty, and the spade connectors loose. I crimped them for a better connection before I tried starting to no change.

Does anyone know what the little black, covered connector behind the engine (just proud of cam cover, at the back, with the wiring going onto the underside of it) not too far from the dizzy caps is? It has wires from the coil etc and almost looks like a diagnostic plug point.
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Re: GT Won't start

Post by Kitch »

saintjamesy89 wrote:I had considered the wiring too Mat, the spade connectors and leads that go from the ignition module to the four spade receptors on top of the coil are quite tatty, and the spade connectors loose. I crimped them for a better connection before I tried starting to no change.

Does anyone know what the little black, covered connector behind the engine (just proud of cam cover, at the back, with the wiring going onto the underside of it) not too far from the dizzy caps is? It has wires from the coil etc and almost looks like a diagnostic plug point.
Ignition module? :lol:
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Re: GT Won't start

Post by mat_fenwick »

Three terminals in the connector? Again, my experience of petrol XUs is pretty much limited to 205s, but I have a feeling some had a connector for plugging in to measure RPM. That is assuming it's not the connector from which the ignition module has fallen off...
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saintjamesy89
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Re: GT Won't start

Post by saintjamesy89 »

Lol, no I know what the IM is now, that's mounted just below the coil. If you draw a line from the bonnet catch or fuel computer measurer toward the rear of the car and a line going left from the dipstick, you'll cross over on the box/plug, it has a tight fitting cover plug that pulls off the reveal the empty socket.

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Re: GT Won't start

Post by mat_fenwick »

Gary wrote:If the earth lead you mentioned is a flat & platted then it goes from the gearbox to the bolt that secures the battery clamp.
I've never seen the arrangement where the gearbox earth lead goes to the battery clamp, so this explains why yours is too short. All the ones I can recall have the lead going direct to the battery, with a smaller lead to the inner wing earthing point. There needs to be a lead of similar size from the battery to either the battery clamp (and hence the gearbox/engine) or somewhere else on the bodywork, otherwise there won't be an adequate reliable return path from the starter motor. A jump lead from -ve terminal to engine, as Kitch said, would do a temporary job for now to prove or disprove whether that's causing your lack of spark.

If the earth path isn't good enough, there will be voltage drop between the starter motor -ve and battery -ve. Say there is 3 V drop across the return path - When cranking the battery voltage may drop to 10 V meaning that the voltage the IM sees (as it shares the same earth path) is only 7 V, which may be too low for it to work.

Any close up photos of this mystery connector Tom?
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saintjamesy89
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Re: GT Won't start

Post by saintjamesy89 »

I tried the jump lead method, but nothing new happened apart from the red enter button on the fuel computer being lit slightly without the ignition on - I can't remember if it does this without the jump lead earth though. I put the earth strap on the clamp bolt and it fit nicely, it's been bent out of shape by a nut and almost fitted against the battery tray (slid on the bolt) perfectly.

So, I need a new coil and IM, and an earth lead from battery negative to the clamp bolt. Is an earth lead special, or just a thick cored copper wire (any coating?)
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Re: GT Won't start

Post by electrokid »

So, I need a new coil and IM, and an earth lead from battery negative to the clamp bolt. Is an earth lead special, or just a thick cored copper wire (any coating?)
No coating needed to this cable - needs to be thick - it may need to take a few hundred amps at times. Copper is best - steel will hardly work and stainless steel will not work at all - too resistive.

If the rev counter is showing the correct rpm while you are cranking then it's possible that the correct pulses are getting to the coil so in that circumstance IMHO it's more likely to be the coil at fault.
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Re: GT Won't start

Post by mds141 »

Tom, these flat copper earth straps can be bought from Halfrauds.
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