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Advice on alternator wiring.


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#1 TR Tim

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Posted 09 May 2018 - 11:30 PM

Hi All

I have a 1971 US Tr6 running on twin Strombergs.

I have had poor running usually when hot and the car loses power.

Initially I suspected fuel starvation and ended up swapping the tank and replacing the fuel lines and fuel pump as the car has sat for a few years prior to my ownership and tank was rusty and blocking fuel filter etc. (needed doing anyway)

Thought this would cure the drop in power

Car still starts fine and seems ok until under load and then it starts to die and the ignition light now comes on either periodically or continually. Checked battery and its reading 12V off and 13.5V at idol. 

Changed the king HT lead and things improved somewhat but after about 2 miles the light started again and power lost.

I have now changed the coil and HT leads and still it persists.  I now strongly suspect the alternator.

I want to change the alternator and have a couple I could try but the wiring is different to that on the car.

The 2 I have use a block with 3 connections and is held in place with a little metal clip.

On the car there are 5 connections.

Earth strap

Thick brown and white wire

Solid brown

brown and white and yellow and white together

single brown and yellow.

Question is how do I wire the newer alternator to this arrangement.

Any help much appreciated.  Its driving me mad.

 

Many thanks

 

Tim


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#2 ed_h

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Posted 10 May 2018 - 12:31 AM

Sounds like there is a problem with the charging circuit, but if you have a solid 12 V or better system voltage, it's hard to see how the alternator would be causing the poor running.  Monitor the voltage at the coil.

 

Would have to know a little more about the replacement alternators to help with wiring.

 

Ed


Edited by ed_h, 10 May 2018 - 12:33 AM.

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For just a little more, you can do it yourself!

 

http://bullfire.net/TR6/TR6%20TOC.html

 

 

 


#3 peejay4A

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Posted 10 May 2018 - 08:10 AM

Inability of the engine to sustain a load is indicative of condenser/capacitor failure if you're still on conventional ignition.


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Pete 

#4 Mike C

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Posted 10 May 2018 - 08:31 AM

I'd  check  the alternator output voltage before I changed it. If you hook a multimeter across the battery terminals and rev the engine after starting you should get 14V or more.

 

I agree with Pete,  missing under load is generally plugs, coil or capacitor.


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#5 RobH

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Posted 10 May 2018 - 08:59 AM

Why do you have a white/yellow wire going to the alternator Tim ?  That is usually the coil ballast bypass wire and should go to the starter solenoid circuit so that it is energised only while the starter operates.  That might be pertinent to the fault you are experiencing since it might affect the ignition. If it is powered all the time it will overheat the coil and after a while that may cause a weak spark or ultimate failure.


Edited by RobH, 10 May 2018 - 09:06 AM.

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#6 stuart

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Posted 10 May 2018 - 09:19 AM

Why do you have a white/yellow wire going to the alternator Tim ?  That is usually the coil ballast bypass wire and should go to the starter solenoid circuit so that it is energised only while the starter operates.  That might be pertinent to the fault you are experiencing since it might affect the ignition. If it is powered all the time it will overheat the coil and after a while that may cause a weak spark or ultimate failure.

71 TR6 shouldnt have a ballast anyway.

Stuart.

Attached File  TR6 wiring Diagrams.pdf   314.64KB   14 downloads


Edited by stuart, 10 May 2018 - 09:20 AM.

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TR4A Royal blue TR5 White  Volvo V70 D5 twin turbo
Plus whatever TR is in workshop for restoration.
 


#7 RobH

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Posted 10 May 2018 - 09:33 AM

True Stuart - but since the wire is there when it shouldn't be, perhaps this car has been modified somehow ? 


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