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21
If you just connected the original wiring to a new coil the resistor will still be active and the new coil won't like it.

Start the engine - sounds like it will idle OK in Park - put a multimeter on it, positive lead to coil positive, negative lead to a good earth. If it reads 12 volts or more your issue isn't the resistor still being in the circuit. If it reads 9 or so, the resistor is still active.

The pink resistor wire is found at the back of the starter switch. You may have to google how to remove the switch. A few centimetres downstream of the switch there is a kind of bulge in the pink wire which is the resistor. On the engine side of the firewall this pink wire changes colour.

As Shane said, you can either connect a new wire direct to the starter switch, or use the pink wire - whatever colour it is under the bonnet - to trigger a relay that then connects 12 volts direct from the battery.

All of that said, reading the symptoms again I'm starting to think this won't be the issue (but its easy to check and fix so worth doing). As I said, mine wouldn't idle below about 1,200 revs until I sorted this out. It sounds like your's is OK at normal idle in Park but can't handle the 100 or so rpm drop when it goes into gear.

I wonder if its some sort of weird issue with the neutral safety switch?

Anyway, I'm sure you'll get it sorted.

Thanks Geoff...I will give as you said a go, the fact that the motor can idle low or high no problems in Park makes me think torque converter, as all these issues where around with old motor, old distributor, old coil etc. the only things I havent changed are the C4 and the holley....cheers Rob
22
If you just connected the original wiring to a new coil the resistor will still be active and the new coil won't like it.

Start the engine - sounds like it will idle OK in Park - put a multimeter on it, positive lead to coil positive, negative lead to a good earth. If it reads 12 volts or more your issue isn't the resistor still being in the circuit. If it reads 9 or so, the resistor is still active.

The pink resistor wire is found at the back of the starter switch. You may have to google how to remove the switch. A few centimetres downstream of the switch there is a kind of bulge in the pink wire which is the resistor. On the engine side of the firewall this pink wire changes colour.

As Shane said, you can either connect a new wire direct to the starter switch, or use the pink wire - whatever colour it is under the bonnet - to trigger a relay that then connects 12 volts direct from the battery.

All of that said, reading the symptoms again I'm starting to think this won't be the issue (but its easy to check and fix so worth doing). As I said, mine wouldn't idle below about 1,200 revs until I sorted this out. It sounds like your's is OK at normal idle in Park but can't handle the 100 or so rpm drop when it goes into gear.

I wonder if its some sort of weird issue with the neutral safety switch?

Anyway, I'm sure you'll get it sorted.
23
What Glenn said.

Original points set up had a resistor in the circuit reducing voltage to the coil to about 9 volts once the engine was running. Early Pertronix distributors were OK with this but newer ones and your Bosch need the full 12 volts.

I had this issue when I put the new engine in a few years ago. The old one had a Pertronix kit in it and I assumed the resistor had been bypassed but the new engine with an MSD in it would start but died if the idle fell below about 1,200 rpm.

I eventually tested my assumption and found only 9 volts at the coil. That's when I learned that early Pertronix kits were OK with the lower voltage. Bypassed the resistor and the problem was solved.

Hi mate
How do I test for 12 volts at the coil? and where is the resistor wire located? cheers Rob 
24
What Glenn said.

Original points set up had a resistor in the circuit reducing voltage to the coil to about 9 volts once the engine was running. Early Pertronix distributors were OK with this but newer ones and your Bosch need the full 12 volts.

I had this issue when I put the new engine in a few years ago. The old one had a Pertronix kit in it and I assumed the resistor had been bypassed but the new engine with an MSD in it would start but died if the idle fell below about 1,200 rpm.

I eventually tested my assumption and found only 9 volts at the coil. That's when I learned that early Pertronix kits were OK with the lower voltage. Bypassed the resistor and the problem was solved.

I have changed the distributor and coil to match to Bosch electronic, didn't make any difference to stalling issue from Pertronix set up, motor runs well in park or neutral only cuts out under load even if a fast idle? What is the chances its the transmission or vacuum or holley 600?
25
Has the cam been upgraded from stock? Is it possible that it requires a higher stall speed to stop it bogging down under load? Have you tried simply increasing your idle speed (within reason)?

Evan.

Hi Evan,
Its fairly high already, its a rolling cam but mild, I had same issue with stock cam....I can drive for ages in "drive" try to reverse and it just bogs down instantly and cuts out when I engage reverse after park? Only things left to replace or rebuild are holley 600 & torque converter or a vacuum issue?
   
26
Tech Torque Pre 1973 / Re: 67 Coupe 289 Auto starting issue
« Last post by Gabs64 on November 21, 2020, 10:10:37 AM »
They are back as should be but i feel that may have been a seperate issue as I got them back by playing around with the turn switch connector plug and just unscrewed and reseated the switch itself in the steering wheel around the same time i sorted out the other prob. I cant give a definite answer on that one. I have a turn switch coming (due Monday) and I will replace it anyway since I have the steering wheel off and the seats out so access is better just to be sure.
27
Don't assume that because you have a '12 volt coil' you will be getting 12 volts to the distributor.

As GEOFF289 said below "I eventually tested my assumption and found only 9 volts at the coil" - you should check that you are getting 12 volts at the coil.

The 'Pink' resistor wire designed into Ford wiring looms is there to ensure that once the car has started, only 9 volts (approx.) is provided to the distributor so that the points don't burn out.  A higher 12 volts is only provided during start cranking.

If you have replaced the distributor with one that requires a constant 12 volts, you must take the pink wire out of sequence. Either by replacing it in the loom, or by using it to power a relay that then provides a direct 12 volt feed from the battery to the coil/distributor.

If you test the voltage at the distributor with the ignition on but the engine not running it'll show 12 volts even with the resistor in the circuit. You have to test it with the engine running.
28
Tech Torque Pre 1973 / Re: 67 Coupe 289 Auto starting issue
« Last post by Gabs64 on November 21, 2020, 09:51:40 AM »
Hi Evan,

No wont start in gear neutral switch doing its job. I can only think that maybe it was set up that way to make it child proof or something like that. I might actually tuck up switch away somewhere and turn it into a kill switch set up.

29
Yes, have a new coil so full 12 volts match to electronic Bosch distributor.

Don't assume that because you have a '12 volt coil' you will be getting 12 volts to the distributor.

As GEOFF289 said below "I eventually tested my assumption and found only 9 volts at the coil" - you should check that you are getting 12 volts at the coil.

The 'Pink' resistor wire designed into Ford wiring looms is there to ensure that once the car has started, only 9 volts (approx.) is provided to the distributor so that the points don't burn out.  A higher 12 volts is only provided during start cranking.

If you have replaced the distributor with one that requires a constant 12 volts, you must take the pink wire out of sequence. Either by replacing it in the loom, or by using it to power a relay that then provides a direct 12 volt feed from the battery to the coil/distributor.


30
Tech Torque Pre 1973 / Re: 67 Coupe 289 Auto starting issue
« Last post by scollist on November 21, 2020, 09:43:30 AM »
Nailed it!!! solved.

In my earlier posted I mentioned that there was a relay under the dash near the fuse box and it looked like a factory loom. I took a deeper dive under the dash and found that relay had been deliberately added. From my limited knowledge it appears the wire running from the loom under the dash to the ignition coil had been cut and the relay put in between. This is where the wire to the break switch comes in as there was a wire spliced into the 12v switched side of the switch to the relay so when the brake pedal was pressed it supplied 12v to the relay energising it and sending the voltage to the coil. I removed the relay and wire bridged those two terminals and wouldn't you know it starts as any normal car now. i will need to do a permanent fix but I will just wait and see if I have created any other issues that that set up was masking.

Thank you all for your support and suggestions as they all really helped.

So we determined it is was a deliberate addition, and removing it makes starting the car work as per factory (your original stated problem).

But later on you mentioned that you didn't have brake lights. In removing the relay has this problem been fixed?
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