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MartinB

Issues with my GT

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MartinB

Back in November I broke down a week after getting the car back on the road (alt pulley sheared off the crank pulley). This time, I was in traffic and the car just cut out - wouldn't start again.... The RAC man was quite thorough in his attempts to get me back up and running, but a few things prevented him.

 

1: battery was flat

2: no spark from coil

 

I later found out that the battery + to starter motor cable was loose so I refitted it, fitted a new battery and it cranks now (this could have caused the battery to not be taking a charge perhaps). He actually had a new coil in his van, but this didn't work.

 

I haven't properly got my hands dirty with it since November, however here are my observations:

 

1. fried wires going to the coil (see pics)

2. fuel pump primes as normal (does this rule out hall sender?)

3. tried a spare dizzy/hall sender - no joy

 

So my thoughts are to fix the wiring, but why could the brown wires be getting fried? I'd presume a short from somewhere, or could a duff coil be causing the wires to melt? 

 

 

Jjj5kgXh.jpg

 

W0sglvRh.jpg

 

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steveo3002

if brown = earth?

 

car trying to earth the main starter circuit through that because the main ones faulty  

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kiran_182

Is that not a sign of resistance in rhe circuit somewhere? Are the earths all good, batrery neg to inner wing? 

 

Do your relays get really hot?

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kwijibo_coupe

Sounds like you have a short somewhere, but it would usually pop a fuse or two. 

If it were me and you had the time I'd remove all the loom and check the continuity of all the wires especially the earths. Maybe even unwrap and then re-wrap the loom so you can check for any breaks in the insulation.

Finally make sure all the engine earths have a good solid connection and maybe add in one that goes direct from the block to the battery negative just for good measure.

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kiran_182

Open the tab on the top of the coil and make sure its all clean and tight 

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MartinB

Got the meter out at the weekend - despite the melted wires, i was still getting 12v to the coil plug to my surprise. Also continutity from the battery to the all earth tabs including the coil to gearbox earth. Tried a spare coil and no luck, also the same for the spare dizzy that I also tried - it makes me think that I could have duff spares! 

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steveo3002

a hair size strand will carry 12v....but can it carry lots of amps ? no it would melt 

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MartinB

Fair point 😎

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steveo3002

that brown is just a common earth...no reason you cant get a length of wire and some jt terminals , replace the wire and run it to a known good earth or the battery post and see what happens 

 

my thoughts are the car has earthing issues...might be wrong but a bit of wire isnt going to cost you alot

 

make sure the batt to body , alternator bracket and coil bracket to gearbox earth are all good and tight/clean

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steveo3002

to test the hall sender ...remove the dizzy but leave the connector on , ign on and turn the rotor arm the pumps should prime 

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MartinB
2 minutes ago, steveo3002 said:

that brown is just a common earth...no reason you cant get a length of wire and some jt terminals , replace the wire and run it to a known good earth or the battery post and see what happens 

 

 

My thoughts are the same for this - easy to run a seperate cable to the coil from the battery or similar. 

 

The earth straps are all tight and in good condition - they were replaced just over a year ago and made by nige8021 - a definite upgrade over the stock items I had

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steveo3002

if a temp cable fixes it ...i would unwrap the loom and take a better look , as loads of browns are all crimped into one up near the turret then goes to the battery , so if there was an issue with one then all could be effected , damaged wires could still be enough for a sensor or small load but not enough for the coil

 

wouldnt be the end of the world to repair it all properly 

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steveo3002
MartinB
steveo3002

edited it now

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MartinB

Tested the hall sender this evening and each time I turn it I can here the fuel pump priming and the injectors clicking, which is good news. 

 

Also put my new coil plug on the coil and earthed the brown wire to the battery, piggybacked the positive and signal (black and green wire) to the existing connector and still nothing!

 

The plot thickens... Time to warm up 😭

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steveo3002

this is with a new coil?

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MartinB

It was with a spare (that I am assuming works!). I think i need to get my hands on a known-working one to start with.

 

Tidied my garage recently so I can get the Polo inside and start unwrapping the loom to look for broken down wiring.

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steveo3002

have you confirmed with a multimeter that the wiring the coil is showing what it should ?

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MartinB
23 hours ago, steveo3002 said:

have you confirmed with a multimeter that the wiring the coil is showing what it should ?

Gonna get my dad over to check - my limits with a multimeter are voltage and continuity checking! 

 

Ordered a spare working coil yesterday as well as squeezing the Polo into the garage. I also worked out that I have too many bikes (although more fun than Poloing!)

 

n2wyLKvh.jpg

 

vCaRO1ih.jpg

 

 

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MartinB

Unwrapped loom tape this evening, found the sections of earth's connected to each other and also 2x lives connected together that also feed the coil.

 

Thought I'd connect my new coil + and - to these points, and the signal/ black and green wire to the existing connector and still nothing! Whipped off the king lead and no spark when earthing it to the chassis either. 

 

Could it be something else... There's no other signs of burnt wiring either. How does the ECU relate to this, if at all? 

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GatisGirdenis
On 21/01/2019 at 11:15, steveo3002 said:

that brown is just a common earth...no reason you cant get a length of wire and some jt terminals , replace the wire and run it to a known good earth or the battery post and see what happens 

 

my thoughts are the car has earthing issues...might be wrong but a bit of wire isnt going to cost you alot

 

make sure the batt to body , alternator bracket and coil bracket to gearbox earth are all good and tight/clean

Speaking about earthing issues. Once my negative battery terminal started breaking apart and when I went to start the car it tried to earth the starter through the stalks on the steering column, even saw some smoke happening, but didnt get to the point to melt the wires.

 

But OP seems to have checked the grounds, so could be an issue elsewhere

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MartinB

Had a couple of weeks away from the car. Anyway, to recap...

 

Tested a 100% working coil from. My brothers 6n and still nothing. 

 

Whipped an injector out and she's getting fuel. So far... Dizzy/Hall sender tested and working, coil working, coil getting 12v. Fuel pump primes when ignition is on, and when rotating the dizzy by hand. 

 

Am I right in thinking that the ECU controls the fuel pump, therefore my tests have proven the fuel pump and ECU relays work? 

 

Getting continuity between the ignition switch and coil positive, and continuity between earth and earth on the coil connector.

 

I think the only thing left to rule out is the ECU, in particular the signal between the ECU and coil. 

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MartinB

Sourced a working ECU and still no luck! 

 

I have at least one spare GT engine bay wiring loom tucked away at my brothers place, so I think it's time to try a new loom and see what's happening... 

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