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1979 Ford f350 6cyl. standard trans.


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Pops Pinky
New User

Nov 6, 2016, 9:06 AM

Post #1 of 7 (1501 views)
1979 Ford f350 6cyl. standard trans. Sign In

My 1979 Ford Dump truck won't stay running ? it starts but when I release the key it dies. It has a dura spark ignition system. I changed the ignition module and still have the same problem. I measured the resistance of the pickup coil and it is 615 ohms. there is supposed to be ballast resistors in this circuit but I haven't found them. This truck has been sitting for quite awhile. I have given it new fluids etc. and even pulled the gas tank and flushed it. I installed a new fuel pump, new start solenoid, and Starter. all this has gotten me to this point. I am getting frustrated and need HELP Please!


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 6, 2016, 12:00 PM

Post #2 of 7 (1497 views)
Re: 1979 Ford f350 6cyl. standard trans. Sign In

Educated guesses for you: It's not fuel at all with those symptoms. It's not the distributor either as it does start. Stop looking or messing with stuff as it's old and just touching too much you'll cause problems unless clearly called for.


This is more likely dropping out spark when you let go of the starter key area - that should be when it switches from unbalasted spark power to balasted spark either at the module or a separate item usually white porcelain and many on firewalls. I doubt that - high bet that's done in the module usually on a fender and either a blue plastic part where you plug in or yellow or it's the wrong one but could fit.
Sorry that I can't be any more specific as it is bigger a vehicle than I would take on for anything for that area of time. This much more smacks of an ignition switch issue cutting out power to "run" when you let go of the "start" position. It actually could be in the dash with the key goes in and behind that and not sure,


T
(edit) Thought of an easy test. Solenoid is on an inner fender well close to primary battery. One of the smaller terminals is to trigger starter which in turn enables ignition then the other small one goes on to resistor. That should light with a test light when key is in "run" position and about can't be if ignition switch isn't sending the power to it. Chase backwards from that or forwards from ignition switch for where it cuts out might be easiest, T
(edit 2) Found ballast for checking. Looks like this....

Now check that with test light or voltmeter when it should be on "run." Should be battery voltage at one side and much lower on the other closer to 6v with engine off, key on. Not that common but neither is a Ford truck lasting this long! Tom



(This post was edited by Tom Greenleaf on Nov 6, 2016, 12:57 PM)


Pops Pinky
New User

Nov 7, 2016, 2:02 PM

Post #3 of 7 (1471 views)
Re: 1979 Ford f350 6cyl. standard trans. Sign In

 I have been looking for this ballast resistor and haven't had any luck. I am beginning to think it may be part of the pickup coil or built into the ignition module. I guess I'll Look some more tomorrow. Tks for the suggestions...


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 7, 2016, 2:12 PM

Post #4 of 7 (1470 views)
Re: 1979 Ford f350 6cyl. standard trans. Sign In

Does the coil have 2 wires on the + side. Many vehicles use a resister wire instead of an actual resister.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Pops Pinky
New User

Nov 8, 2016, 7:20 AM

Post #5 of 7 (1453 views)
Re: 1979 Ford f350 6cyl. standard trans. Sign In

The coil only has one wire on the + side


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 8, 2016, 7:30 AM

Post #6 of 7 (1449 views)
Re: 1979 Ford f350 6cyl. standard trans. Sign In

Well, unless there is a splice somewhere before the coil, that pretty much eliminates the resister theory. You probably want to start at the ignition switch and verify power out in the "ON" position and track it out to the coil.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Pops Pinky
New User

Nov 9, 2016, 6:58 AM

Post #7 of 7 (1430 views)
Re: 1979 Ford f350 6cyl. standard trans. Sign In

If I get time today I will give your suggestion a try. TKS






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