Coil supply wire- now bought a meter!

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BryanM
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Coil supply wire

Post by BryanM » Fri Sep 28, 2018 6:51 pm

Been away all week but back now to trying to stop the hot starting problem.

New leads, condenser, points and coil and still the same problem but tonight a solution but not a permanent one! New battery so,turns over very strongly and a check with a circuit tester, I don't have a meter, showed the col is getting volts, although I don't know how many, when starter is cranking made me think couldn't be a problem there.

However putting a direct feed into the coil from the battery and she fires up first turn of the starter as she does when cold !
Two or three goes swapping back and forward just to make sure and definitely direct feed cures the problem. Obviously switching the key off doesn't kill the engine until wire from battery disconnected so where is the best place to take an ignition fed lead from to make it all work again?



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scimjim
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Coil supply wire

Post by scimjim » Fri Sep 28, 2018 7:39 pm

The existing wire runs from the ignition switch to the coil via the tacho - you need to find out where you’re losing power in that line rather than bypass it.


Jim King

Current: SE5 (8Ball), TI SS1 (snotty), 1600 SS1 (G97), 1600 SS1 (C686CCR), 2.5TD SE5a (diesel 5a), 6 x random other SS1s.
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Old and Slow
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Coil supply wire

Post by Old and Slow » Fri Sep 28, 2018 8:16 pm

If you have the same type of tacho as me, you should find there is a bullet on one wire onto the tacho and a socket on the other, so it should be possible to unplug these on the back of the tacho and plug them directly together, which bypasses the tacho. This might help identify the cause of your problems.
Good luck!


Philip Needham
Ashley-bodied TR3; '54 Ford Consul; '55 AC 2-Litre Saloon;'65 850 Mini; '70 Ford Zodiac MkIV; XR3i
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BryanM
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Coil supply wire

Post by BryanM » Fri Sep 28, 2018 8:52 pm

Will try that on Sunday. Out autotesting the K Series Midget tomorrow but may be something to do with the auxiliary rev counter fitted on top of the dash which isn't working although the standard one works fine. At least I now know what the problem is!



BryanM
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Coil supply wire- now bought a meter!

Post by BryanM » Mon Oct 01, 2018 9:12 pm

Follow on from previous post. Bought a meter and tried a few things. Took out rev counter and joined two bullet connectors but no difference. Voltage readings are
Ignition on supply to coil 11 volts
Disconnect’-‘ to distributor jumps to 12.3
Cranking supply to coil drops to between 7amd 8 volts
Cranking with distributor disconnected 8.8 volts

Haven’t been able to replicate the hot starting issue as have to move between garage and carport 4 cars and drive 15 miles and don’t have time tonight but do these figures give anybody any clues? Was talking to a couple of people at the auto test on Saturday and strong suggestion was made it could be the ignition switch but I thought it would either work or not work.



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Coil supply wire- now bought a meter!

Post by scimjim » Mon Oct 01, 2018 9:20 pm

The figures don’t sound too bad (which fit your symptoms) - you’d like to see nearer 9v cranking. You need it warm as the original fault only occurred when hot.


Jim King

Current: SE5 (8Ball), TI SS1 (snotty), 1600 SS1 (G97), 1600 SS1 (C686CCR), 2.5TD SE5a (diesel 5a), 6 x random other SS1s.
Previous: SE5, 3 x SE5a, 2 x SE6a, 3 x SE6b, GTC, 2.9i GTC, 3 x 1600 SS1, 1300 SS1, Mk1 Ti Sabre, Mk1.5 CVH Sabre
Chief mechanic for: 1400 K series SS1 (Megan3), 1400 CVH EFi SS1 (Grawpy), Sabre/MX5 auto (The Flying Broomstick),
1300 SS1 (Number One) & Sarah's coupe.
CURE THE FAULT - NOT THE SYMPTOMS

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Old and Slow
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Coil supply wire- now bought a meter!

Post by Old and Slow » Mon Oct 01, 2018 9:32 pm

Switch contacts can go "high resistance" and will then drop voltage when a current flows through it, instead of failing completely.
However the readings suggest this isn't the problem, as you are getting 3 to 4 volts drop even with the dizzy disconnected (i.e. no current flowing in the coil).
Check the voltage across the battery when you turn the starter; if this shows the same value (8.8v) then perhaps you need a new battery?
If not, then check the earth straps etc as there is some resistance somewhere in the circuit causing the voltage drop.
OF course, this doesn't help diagnose your fault occurring when it warms up.


Philip Needham
Ashley-bodied TR3; '54 Ford Consul; '55 AC 2-Litre Saloon;'65 850 Mini; '70 Ford Zodiac MkIV; XR3i
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peter freeman
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Coil supply wire- now bought a meter!

Post by peter freeman » Mon Oct 01, 2018 10:09 pm

As it starts ok with a lead from he battery it sounds like it has ballast in circuit - perhaps the ignition circuit has been modified and it has a 9volt coil fitted as well - my Coupe has. You could run a wire from the battery +ve via a relay which is energised when the engine is cranking ( white/red wire ) then you would have full battery voltage on the coil same as fitting the wire link.



BryanM
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Coil supply wire- now bought a meter!

Post by BryanM » Mon Oct 01, 2018 11:27 pm

Have to go and help a friend with a motorhome problem tomorrow night so will take the Reliant and get it good and hot and see what voltage it is getting to the coil then and that would prove or eliminate the switch . According to eBay a new one is only £12 odd. Thanks for your suggestions.



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