kcsun Posted October 24, 2019 Report Share Posted October 24, 2019 Hi all, went to the garage to start the car and it won't start! It is a 73 PI CR engine with a Luminition system which I fitted 5 years ago and has worked perfectly until now. I turn the ignition on and there is 12v at the coil, I then start churning the starter motor and the voltage at the coil drops to about 9 - 9.5v. The engine does not fire, when I release the ignition switch the engine fires on the release and tries to start???? If it fires successfully the engine runs OK. I do not think there is any spark while the starter is churning but is a bit difficult to see as I have only one pair of arms!! I am assuming it then sparks as the ignition switch is released any ideas?? kc Quote Link to post Share on other sites
Graham Posted October 24, 2019 Report Share Posted October 24, 2019 (edited) Cranking dropping battery voltage so providing poor/no spark stop cranking engine on starter battery voltage increases providing enough power for a spark, engine tries to fire on residual motion from starter ? battery needs charging or is US that’s my guess as a starter anyway (no pun intended) edit do CR series cars use ballast resistors if so might it be an issue there Edited October 24, 2019 by Graham Quote Link to post Share on other sites
brian -r Posted October 24, 2019 Report Share Posted October 24, 2019 Kc Had the same issue earlier this year. Problem traced to failing battery. New battery fitted problem solved. Suggest you try jump starting from a known good battery just to check. Good Luck Brian Quote Link to post Share on other sites
marko Posted October 24, 2019 Report Share Posted October 24, 2019 Sounds like the ignition switch is faulty.....had exactly the same problem several times! Regards Mark Quote Link to post Share on other sites
peejay4A Posted October 24, 2019 Report Share Posted October 24, 2019 +1 Quote Link to post Share on other sites
Mike C Posted October 24, 2019 Report Share Posted October 24, 2019 (edited) I'd look at the ballast resistor and it's wiring. I made a gadget out of stuff in the shed incorporating a PVC tube with a wire from the distributor lead to earth and an adjustable spark gap at the bottom. The tube keeps light out and lets me see the spark. The adjustable gap let's me measure it's strength. But you might have to check for a spark at night if you suspect the ballast resistor. Edited October 24, 2019 by Mike C Tried to reduce photo size. Quote Link to post Share on other sites
kcsun Posted October 24, 2019 Author Report Share Posted October 24, 2019 Thanks for your replies, will check the battery after work tomorrow, i will charge it up and connect my "jump pack" to the battery to add a bit of boost and see what happens I was thinking about the ballast resistor, there is a 12v link wire from the starter motor shown on the wiring diagram, but I do not know where to find the resistor or the "connector block" shown in the wiring diagrams kc Quote Link to post Share on other sites
RobH Posted October 24, 2019 Report Share Posted October 24, 2019 (edited) The resistor is actually resistive wire and is part of the loom, so you can't really see it. The ballast resistor isn't doing much when cranking as the wire from the starter is supposed to be giving the full 12v to the coil. Since you only measure 9-and-a-bit either that link has a bad connection (which might include the switch although that apparently is operating the starter solenoid OK) or your battery is low on charge as Graham says. Edited October 24, 2019 by RobH Quote Link to post Share on other sites
Mike C Posted October 24, 2019 Report Share Posted October 24, 2019 My 1969 CP's ballast resistor is a white ceramic thing on the rear passenger side of the engine bay if this helps. Quote Link to post Share on other sites
astontr6 Posted October 25, 2019 Report Share Posted October 25, 2019 12 hours ago, Graham said: Cranking dropping battery voltage so providing poor/no spark stop cranking engine on starter battery voltage increases providing enough power for a spark, engine tries to fire on residual motion from starter ? battery needs charging or is US that’s my guess as a starter anyway (no pun intended) edit do CR series cars use ballast resistors if so might it be an issue there CR cars have a resistive wire which does the same thing as ballast resistor. I got rid of that system years ago by by-passing that wire. If you do this you have to change the coil as well as it is a 6 volt coil which is meant to give a bigger spark when starting???. I would change the coil to a 12 volt type and do a temp lash up power supply to the coil and see what happens! This can easierly be done taking the SW power from the fuse box! I did this for another TR owner this year when he have trouble with that resistive wire! Bruce. Quote Link to post Share on other sites
stuart Posted October 25, 2019 Report Share Posted October 25, 2019 9 hours ago, Mike C said: My 1969 CP's ballast resistor is a white ceramic thing on the rear passenger side of the engine bay if this helps. That will be an aftermarket alteration as thats not original.Jaguars of the period had the same thing. Stuart. Quote Link to post Share on other sites
RogerH Posted October 25, 2019 Report Share Posted October 25, 2019 Hi KC, if it tries to start after you disengage the 'starting' position on the switch then the ballast resistance wire (Red/White) looks as if it is OK. Check out the White/Yellow starting wire that should give 12V to you coil with the starter motor spinning. This may be open circuit. http://www.advanceautowire.com/tr2506.pdf Roger Quote Link to post Share on other sites
Waldi Posted October 25, 2019 Report Share Posted October 25, 2019 I’m with Roger, good thought. Waldi Quote Link to post Share on other sites
kcsun Posted October 25, 2019 Author Report Share Posted October 25, 2019 Update for you As Roger said I checked the wire from the starter motor, which fell apart when I touched it, remade the connection ---- and no difference. So last night I put my large battery charger on the battery (up till then I had only been using my small trickle charger (which always lit up to say the battery was fully charged!!) anyway went out to garage this evening, connected the battery and whoosh -- started first time Battery obviously was never fully charged as Graham and Brian suggested Will check everything more fully tomorrow but think it is cured (note to self - never trust the green light on a trickle charger, no it wasn't a C-Tek) kc Quote Link to post Share on other sites
matttnz Posted October 30, 2019 Report Share Posted October 30, 2019 On 10/25/2019 at 9:18 PM, RogerH said: Hi KC, if it tries to start after you disengage the 'starting' position on the switch then the ballast resistance wire (Red/White) looks as if it is OK. Check out the White/Yellow starting wire that should give 12V to you coil with the starter motor spinning. This may be open circuit. http://www.advanceautowire.com/tr2506.pdf Roger PM me KC if you need a CR wiring diagram. The AAW website doesn't have it Quote Link to post Share on other sites
Waldi Posted October 30, 2019 Report Share Posted October 30, 2019 (edited) Or use the diagrams in Rogers link. The ballast resist wire is shown however in the bottom four diagrams in Rogers link. Regards, Waldi edit: During starting the YW wire provides current to the coil, it will be a bit less than 12V because you are cranking. Once you let loose the ignition switch/button, the YW wire will no longer be “fed” directly. Now the (reduced) voltage is provided by the WR ballast wire. Edited October 30, 2019 by Waldi Quote Link to post Share on other sites
matttnz Posted October 31, 2019 Report Share Posted October 31, 2019 21 hours ago, Waldi said: Or use the diagrams in Rogers link. That's the AAW link that has every single wiring diagram except for for CR cars Quote Link to post Share on other sites
graeme Posted October 31, 2019 Report Share Posted October 31, 2019 On 10/24/2019 at 11:24 AM, kcsun said: Hi all, went to the garage to start the car and it won't start! I turn the ignition on and there is 12v at the coil kc If KC has 12v at the coil when not trying to start, then there is no ballast system! Graeme Quote Link to post Share on other sites
Waldi Posted October 31, 2019 Report Share Posted October 31, 2019 4 hours ago, matttnz said: That's the AAW link that has every single wiring diagram except for for CR cars Yes, but the relevant part is shown there, so they could be used to investigate this issue. Regards, Waldi Quote Link to post Share on other sites
matttnz Posted November 1, 2019 Report Share Posted November 1, 2019 (edited) Not completely because of the ballast wire and connections. Basic principle of course is similar I agree, but chasing connections down off those AAW diagrams can be exasperating at times. ] Edited November 1, 2019 by matttnz Personal muppetry Quote Link to post Share on other sites
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