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Old 06/13/18, 02:45 PM   #1
Dandesjar
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Canada
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No spark when cranking, starts in ON position

Ok, after 2 years of restoration my Bronco if finally running. Except for a couple of electrical issues it seems to be running pretty well. Iím still trouble shooting a gauge problem but my first priority is figuring out why I have no spark when I crank the engine. It wonít fire while Iím cranking but as soon as I release the key to the On position it starts to get spark and usually still has enough RPM from cranking to fire the engine. Anyone have some basic trouble shooting tips or ideas on where to start looking?

It has a new painless harness and ignition switch.
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Old 06/13/18, 03:15 PM   #2
rmk57
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Try reversing the two small wires on the starter relay. Either that or you have something not wired correctly in the switch.
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Old 06/13/18, 03:25 PM   #3
ransil
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Should be an I terminal on the solenoid that sends voltage to heater ignition module you have to get it running during cranking, 12 volts comes grom a different place in run, you have that one correct.

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Old 06/13/18, 07:19 PM   #4
75MIKE
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My Bronco was doing the same thing and I just fixed it with a new ignition switch. Do you still have your old switch you could try?

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Old 06/13/18, 07:31 PM   #5
Dandesjar
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I do. I’m going to give that a try first. I’m thinking the switch is probably good though... I have a FiTech unit and the white ignition wire that feeds it is powered when cranking so the switch is obviously feeding voltage to at least some components while cranking.

Does anyone know if there is a simple way to bypass the ignition switch by jumping the starter solenoid, rather than pulling the entire switch out of the dash to test it?
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Old 06/14/18, 06:13 AM   #6
ntsqd
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What ignition system are you using? This is a common thing to have happen with a Dura-Spark II conversion.

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Old 06/14/18, 06:32 AM   #7
Dandesjar
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I have an 6AL box, ready to run distributor, and coil ... so all MSD stuff.
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Old 06/14/18, 06:41 AM   #8
bmc69
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The "I" post on the starter solenoid is where the ignition system gets it's power while the engine is cranking. Sounds like you are missing a connection to that.

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Old 06/14/18, 06:51 AM   #9
ntsqd
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Quote:
Originally Posted by Dandesjar View Post
......
Does anyone know if there is a simple way to bypass the ignition switch by jumping the starter solenoid, rather than pulling the entire switch out of the dash to test it?
"Short" from the battery + stud to the 'S' terminal on the relay. Before you do this, put a voltmeter or a test light on the 'I' terminal on the relay, see if it has power when you short it.

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Old 06/14/18, 11:59 AM   #10
DirtDonk
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Do you have a standard Ford starter relay like the original style? Or a more modern one that only has the small "S" terminal but not the "I" terminal?
Got pics of under the hood in that area?

Where is the White FiTech wire coming from? Directly from the ignition switch, or somewhere else?
Are you using a ballast resistor in this ignition setup? You should not be, so I wanted to make sure.

Things you can test easily with a volt/ohm meter:

1. If you have the Brown "I" wire connected to the starter relay, pull it off and measure voltage with the key in RUN. If it is not powered there is a break in the circuit somewhere.
In theory you no longer need this Brown wire anyway, since you are running an MSD setup that takes the full 12v of your system. But it should not hurt anything to keep it in place, as long as the starter relay is not shorting it out somehow.

2. From the back of the ignition switch, or up at the ignition box you will have a Red w/green stripe wire. Should have battery voltage in RUN, but should also have it in START, which it sounds like you don't have. However, you should test that theory anyway.
With both the Red w/blue "S" wire and the Brown "I" wire disconnected from the starter relay so the starter does not crank and you don't get a false signal to the other wires, have a helper turn the key to START while you test for full voltage at the Red w/green ignition wire. If power is present at RUN, but it goes away in START, your ignition switch is bad.

Remember, "new" does not mean "good" anymore.
And if any of those voltage readings you are taking are less than they should be, find out why. Even with all that wire, this new Painless system should have very minimal voltage drops along it's length.
If you find more than a half-volt drop anywhere, find out why.

Good luck.

Paul

'71 Wagon, 3.5" WH, F150 disc brakes and steering, 4.11 33x11.50 Thornbirds, Kayline soft top, Hanson bumpers. "Built, not bought"

'68 LUBR, 2.5 + 1 WH, 31x10.50, 4.56, Explorer and 4R70w by EFI Guy, WH disc brakes, Hanson front bumper, Warn winch. "Bought, not built"

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Old 06/14/18, 08:05 PM   #11
Dandesjar
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Man... great info.

Problem solved. I didn’t see any harm in reconnecting the brown wire between the I terminal & the coil. Evidently, with the 6AL box connected, the signal from this wire somehow interferes with the ignition system during Start. After some testing, I left this wire disconnected and it fires up right away with the key in start.
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Old 06/15/18, 11:57 AM   #12
DirtDonk
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Hey, congrats! Good to have it running.
Now on to the next bugaboo!

Paul

'71 Wagon, 3.5" WH, F150 disc brakes and steering, 4.11 33x11.50 Thornbirds, Kayline soft top, Hanson bumpers. "Built, not bought"

'68 LUBR, 2.5 + 1 WH, 31x10.50, 4.56, Explorer and 4R70w by EFI Guy, WH disc brakes, Hanson front bumper, Warn winch. "Bought, not built"

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