Very ODD Ignition problem. Need ideas from you
Thread Starter
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Senior User
Joined: Dec 2014
Posts: 288
Likes: 2
From: Pocahontas, Iowa.
Very ODD Ignition problem. Need ideas from you
Hi all.
I'm back.
I have a very odd issue here.
I went out to start the old boy and he refused to fire up.
SO...
I checked for fuel at the carb... Got fuel from the accelerator pump
Checked spark...no spark.
Took out a DVM and tested voltage at the + side of the coil....4.5 volts.
Yep...4.5
No wonder.
I jumped from B+ to the positive side of the coil and the engine lit right up.
I had an appointment so I left it hot wired. It ran better than it has in a long time. Smooth idle, snappy acceleration.
I left the key in the "ON" position and pulled the hot wire when I got to my destination. The engine continued to purr.
I can't figure this one out. If it's the ballast resistor wire that's bad, as soon as I disconnected the hot wire it SHOULD have died.
Could it be the ignition switch itself? I've never heard of such a thing.
Bill
The Kingdom Electrician. AKA "Sparky"
Cargo Master
Joined: Sep 2007
Posts: 2,470
Likes: 535
From: Chandler, AZ
Given the coil (or 'ballast') DC resistance being roughly the same resistor wire, you should get about 6V on coil+.
Given your 4.5 volts, you could have either:
1) low battery
2) Ignition switch is adding resistance.
3) ballast wire is damaged and resulting resistance is more like 3 ohms.
you should be able to measure voltage at switch and determine #2 from #3, given coil primary R.
Given your 4.5 volts, you could have either:
1) low battery
2) Ignition switch is adding resistance.
3) ballast wire is damaged and resulting resistance is more like 3 ohms.
you should be able to measure voltage at switch and determine #2 from #3, given coil primary R.
Fleet Mechanic
Joined: May 2001
Posts: 1,396
Likes: 4
From: Cupertino
You possibly have shorted windings in the coil primary. That would lower voltage on the low side of the ballast resistor even with a good resistor.
The spec on coils is:
1.4-1.54 ohms primary, 7600-8800 ohms secondary. Check and go from there.
The resistor should be 1.3-1.4 ohms .
The spec on coils is:
1.4-1.54 ohms primary, 7600-8800 ohms secondary. Check and go from there.
The resistor should be 1.3-1.4 ohms .
Lead Driver
Joined: Jul 2011
Posts: 8,679
Likes: 191
From: On the Edge of the Desert
What ignition system are you running? Points? If not, now would be a good time to run a new wire to the coil.
I would say switch, or wire, since jumping it made it run great. A bad coil would have overheated and **** the bed with full power on it.
I would say switch, or wire, since jumping it made it run great. A bad coil would have overheated and **** the bed with full power on it.
Cargo Master
Joined: Oct 2011
Posts: 2,246
Likes: 303
From: Kenner,La.
Electrical problem
You may be getting a "feed back" from the solenoid, hard starting is a symptom of a by pass circuit failure. I once took a solenoid apart and the wire for the bypass had broken and was making a "feed back". It sounds crazy but anything can happen to these old trucks.
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Thread Starter
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Senior User
Joined: Dec 2014
Posts: 288
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From: Pocahontas, Iowa.
no hard starting.
almost new MSD Blaster coil
Pertronics ignition
I'll test and report
"By_pass circuit?"
almost new MSD Blaster coil
Pertronics ignition
I'll test and report
"By_pass circuit?"
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Hotshot
Joined: Mar 2013
Posts: 14,255
Likes: 199
From: Phoenix, Az.
Hey Sparky. Nice to see you back.
I think it's the ignition switch, the wiring pigtail connected to it, or both. Especially if you still have the pin style switch. I would look at the wiring for traces of heat and melting. And the switch prolly feels loose as a goose. They are cheap.
I think it's the ignition switch, the wiring pigtail connected to it, or both. Especially if you still have the pin style switch. I would look at the wiring for traces of heat and melting. And the switch prolly feels loose as a goose. They are cheap.
Thread Starter
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Senior User
Joined: Dec 2014
Posts: 288
Likes: 2
From: Pocahontas, Iowa.
Everything seems to be wired properly.
No signs of melting.
I think it could be the switch because it only has done this after sitting in the garage for days in 10 degree temps.
The light switch is acting up too. (its old like me)
Along with the fact that it runs well after being hot wired.
Fully charged battery.
Turns over quickly.
I wonder if taking the switch out and spraying it down with a contact cleaner might help. I know it could make things worse too.
No signs of melting.
I think it could be the switch because it only has done this after sitting in the garage for days in 10 degree temps.
The light switch is acting up too. (its old like me)
Along with the fact that it runs well after being hot wired.
Fully charged battery.
Turns over quickly.
I wonder if taking the switch out and spraying it down with a contact cleaner might help. I know it could make things worse too.
Logistics Pro
Joined: Aug 2015
Posts: 4,093
Likes: 14
From: Lind, WA- Eastern WA
If you still have the older style "round pin" ignition switch, it could be on it's way out. As long as the resister wire is connected correctly, and not cut, there's not much that can go wrong with it. If the coil and the battery, tests good, then you have really narrowed it down to the switch or the starter solenoid.
Thread Starter
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Senior User
Joined: Dec 2014
Posts: 288
Likes: 2
From: Pocahontas, Iowa.
The only thing I see is that the starter solenoid by-passes the resistor to give the coil full 12 volts for start.
It wants to start then dies as soon as I release the switch and let it go the the "RUN" position.
Seems like the switch..
Is 7.95 the correct price from LMC truck for a replacement switch? seems odd too.
Bill
It wants to start then dies as soon as I release the switch and let it go the the "RUN" position.
Seems like the switch..
Is 7.95 the correct price from LMC truck for a replacement switch? seems odd too.
Bill
Hotshot
Joined: Mar 2013
Posts: 14,255
Likes: 199
From: Phoenix, Az.
Oh yeah, you have a 1967. Which has a 1967 specific ignition switch. Before the pin style. Yes that is the correct one but so cheap it's scarey to me. And you know it's aftermarket. So I think you ought to call your local parts houses and see if you can get one made ANYWHERE but China.
Or buy a NOS Ford one. Part number C7UZ11572A.
Green Sales
(800) 543-4959
xKarlson Motors
907-225-9022
xManderbach Ford
610-929-3683
NOS Parts Ltd.
Recently Updated
Part Number:C7UZ11572A
Seller:NOS Parts Ltd.
Description:SWITCH ASSY.- IGNITION
Phone (972) 937-2201
Price:Request PricingEmail:Send Seller Email Inquiry
Quantity:3
Location:Waxahachie, Texas
Or buy a NOS Ford one. Part number C7UZ11572A.
Green Sales
(800) 543-4959
xKarlson Motors
907-225-9022
xManderbach Ford
610-929-3683
NOS Parts Ltd.
Recently Updated
Part Number:C7UZ11572A
Seller:NOS Parts Ltd.
Description:SWITCH ASSY.- IGNITION
Phone (972) 937-2201
Price:Request PricingEmail:Send Seller Email Inquiry
Quantity:3
Location:Waxahachie, Texas