12V at coil at ignition RUN but not at START

[esty]

on the 74 we recently finished rewiring we only ran a single wire from fuse 12 to Coil + and all works as it should (that is the only wire to coil +)...there is power to coil when starting with ignition and power to coil in the run position...on the 72 we wired it the same way...we have power at the coil in the run position from the switch but no power to coil when starting the car

 

using a test light shows no power to the coil when trying to to start the car but release key to run and there's power

 

we got the starter issues sorted it was bad ground, now the motor spins like a top but isn't firing and i believe it's the wiring as described above....looking a 2 of 3 wiring diagrams i have, plus one of John's neat hand drawn illustrations show an additional wire to coil + from starter, i assume from solenoid

 

what say you guys...run a wire from solenoid to coil + ??

 

Edited July 24, 2021 by esty

[coloincaalpine RIP 2021]

Wire disconnected or in the wrong position at the ign. switch.

[esty]

6 minutes ago, coloincaalpine said:

Wire disconnected or in the wrong position at the ign. switch.

which wire?

[AustrianVespaGuy]

Hmm, that's interesting because all those green wires from the ignition switch should all be hot in run AND start.  It's only the purple wires that are hot in acc and run positions but NOT in start.  Regardless, running a wire from the starter solenoid will certainly work, and is probably the easiest fix, but I am a bit troubled by the fact that you're not seeing 12v with the key in the start position.  I know you said the ignition switch was untouched, but that'd be the first place I'd suggest checking to see if the terminals are at least getting the proper voltages in the correct positions.

[Son of Marty]

Esty this goes back to your help with your underhood wiring identification thread, the relay pictured is the Roundy ignition relay your 74 has the later simplified start wiring, the early wiring does cut the resistor ignition wire power and routes battery voltage through the relay, on the firewall by the distributor, to help with cold starts, when you let go of the key the resistor voltage is reapplied. the 74 and later cars the battery voltage is provided by the second small wire on the solenoid.

Edited July 23, 2021 by Son of Marty

[coloincaalpine RIP 2021]

The ignition switch supplies power to to the coil in 2 separate positions.  When you are in start position a pole on the ignition switch supplies power to the coil and the starter and when it is released to the run position a separate pole maintains the power to the coil.

Break out the test light. 

[esty]

i forgot to say when i made my 1st post, the car won't start...not getting 12 volts to the coil when starting the car will prevent it from starting...it ain't starting ....i have a new to me IE dizzy with the fake pertronix which steve removed and added authentic pertronix so we don't know how to test for spark but assumed spark is necessary when starting the car and we aint't getting 12 volts when turning the key to start

 

1 hour ago, Son of Marty said:

Esty this goes back to your help with your underhood wiring identification thread, the relay pictured is the Roundy ignition relay your 74 has the later simplified start wiring, the early wiring does cut the resistor ignition wire power and routes battery voltage through the relay, on the firewall by the distributor, to help with cold starts, when you let go of the key the resistor voltage is reapplied. the 74 and later cars the battery voltage is provided by the second small wire on the solenoid.

we just removed that relay, it should not be the cause of the problem now....i think

 

 

[Son of Marty]

No you need it to provide 12v while cranking.

[esty]

OK...

 

[esty]

the 2 green wires that were under the hood, i posted a picture of them, iirc in my 1st post of that last thread about under hood wiring....i removed the wire we ran from fuse 12 and connected the green wire which has poser all the time, including at starting and as soon as steve turned the key, it popped a few times thru the carb...so we have power for lift off

 

gas tank is not in car, fuel lines are not connected yet...he poured some gas in the carb to get the pop and backfiring from the carb that he just got...now, why is the car firing but not starting...we set initial timing by the cam chain pulley, crank pulley and watching the cam lobes as discussed in other thread...

[John76]

Here is a sketch of the ignition switch.

Check to see that everything is plugged in correctly.

The "no voltage to coil" during cranking suggests the resistor bypass relay is not working or wired properly....or one of your green wires is missing or not on the right ignition switch tab. 

 

[esty]

John we got past that problem by connecting the green wire i showed in my last thread, we now have power at starting and running...we did not verify the wires at the ignition switch but they are the way they were the last time we started and drove the car...so unless they changed themselves in the past 10 years i trust they are correct

 

we've reached our limits of know how at this point...there are no instruction books to follow when you have spark and fuel but the car won't start...it pops and backfires thru the carb but will not start and run...we tried turning the distributor slightly both ways to no avail

 

HELP

 

Edited July 24, 2021 by esty

[ray_]

So, the crank pulley was at TDC and the #1 cam lobes closed and the cam timing mark at 12 o'clock?

 

If so, I'd advance the dizzy 10 degrees or so (counter clockwise on a 2002 M10).

 

Good luck!

Edited July 24, 2021 by ray_

[Mike Self]

11 minutes ago, ray_ said:

So, the crank pulley was at TDC and the #1 cam lobes closed and the cam timing mark at 12 o'clock?

And...when the above items were also in alignment, the rotor was pointing to the notch on the lip of the dizzy housing and directly above the notch the dizzy cap terminal was the one holding the lead to #1 spark plug?  It's really easy to get things 180 degrees out of time (ask me how I learned this!)

 

mike

[esty]

26 minutes ago, Mike Self said:

And...when the above items were also in alignment, the rotor was pointing to the notch on the lip of the dizzy housing and directly above the notch the dizzy cap terminal was the one holding the lead to #1 spark plug?  It's really easy to get things 180 degrees out of time (ask me how I learned this!)

 

mike

i'm absolutely certain everything was in alignment when we set TDC and installed the dizzy...the only thing i can't swear to is the Ireland Distributor does not have a notch on the lip of the housing to use as a reference...i was told by others here to point the rotor so it pointed to the number one plug wire on the cap and that should get us close enough

 

tomorrow steve is going try tweaking the dizzy, turning it to see if he can dial it in, if that fails he's going to pull the dizzy, go through the setting to TDC process again, install the old Bosch, with points, that was on the car when we bought it...the radiator and fan are not installed so he can turn and set the engine at the crank

 

start over...do it again