Howdy y'all,
I have a 74 highboy with a 300 4.9 and it won't turn off with the key. I unhooked both battery cables and it still ran just fine. I had to put a rag over the carb and pinch off the vacuum lines to make it die. Can anyone tell me how to fix this? Everyone says it's running on the alternator but I need a salutation, and I'd like to know why it's doing that now. This is the third time in a row!!

 

I had an issue similar to this, I had a shorted out wire coming from the ignition, going to the starter relay or so.e call it a starter solenoid. I bypassed the wire and ran one from the neutral sadety switch under the steering column. But, who knows what could be causing that.

 

Greeting!

Well, at least you know the alternator is in good shape. The battery is really only there to start the engine, after that, it doesn't have much use. It does act as a kind of filter and absorbs voltage spikes and smooths supply from the alternator. But the truck, lights, accessories, everything runs from the alternator.

 

In the future maybe just pull the middle coil off the distributor cap? I have no other help. My truck “diesels” after I turn it off but it ain’t gettin spark.

 

My guess: either starter solenoid or the ignition switch in cab. There is a possibility of a shorted wire somewhere though. Solenoids are not expensive, so I would start there.

 

Two common failure points are the ignition switch and the starter relay.
You can easily test the starter relay the next time it keeps running by removing the small Brown wire from the "I" post on the front of the relay. If it stops running, then you have an internal short in the old relay and it needs to be changed.
Or just leave the Brown wire off!
And of course, all the usual admonishments to buy a good high quality relay and not just one based off of cost apply. We can no longer assume we're getting a good one from the usual parts stores, and have many fail within a few starts, if not right out of the box!

If it keeps running after pulling the Brown wire, there is power being applied to the positive side of the ignition coil. Usually that's a fault in the switch, but it could come from a number of sources after the wiring has been hacked for the last 45 or so years.
What type of ignition system are you running? Stock points still? Or perhaps some form of Ford Dura Spark or aftermarket setup?
Got pics of the under-hood area?

What is the wiring's general condition?

Paul

 

Yes if it is the 3rd time in a row you have a wiring issue some where. And since it is not all the time, its going to be hard to trace down. I would NOT be removing the battery cables trying to shut off the truck, good way to burn up a alternator or other elec items, like a voltage regulator.

X2 on to kill it, just pull the middle coil wire off the distributor cap. You might get a free shock too.

To remove the ignition witch assembly, you have to loosen the outer ring that has 3 notches. Just use a flat tip screwdriver and tap it in the normal loosening direction, then remove all the way by hand, push the switch out the back side of the dash and then unplug it.

You will probably get a new ignition switch WITHOUT the key/tumblers You can just swap them out of the old switch. You know that trick right? Rotate the key to acc (left) and insert a paper clip in the hole right by the key and you'll feel a spring loaded "button" push in and keep turning in the same direction and it should come right out. Don't forget to disconnect your battery first.

Some threads on your original problem https://www.ford-trucks.com/forums/1...+tumblersoblem.

And the key tumbler. https://www.ford-trucks.com/forums/1...-cylinder.html
https://www.ford-trucks.com/forums/1...-and-keys.html

 

Pulling the distributor coil wire would work, but now that I think about it grounding the NEG (-) primary terminal of the coil would save wear and tear (internal arcing) of the coil, (and won't get Zapped!) till things get sorted out.

 

Thanks for all the info!! It has points but I replaced the whole distributor after I put a new motor in a few months ago it hasn't been used alot since.
I have a new starter and solenoid I bought an ORIELLYS starter and solenoid and they both died within 3 cranks on the new motor and I replaced them with napa parts.
This started happening right after I installed the new starter and set the timing to 10° btdc with the timing light. When I turn the key off the oil light comes on like it normally does with you turn the key one click.
I am going to go tinker with it tonight and see what I can find.
I can try to get some pics to post on here too!!

Thanks again!

 

Thank you!
I pulled the battery cables off because I wasn't sure how to stop it but thank you for lettin me know all that! I did pull the coil wire off once and I almost lost my socks!!! The electric fence didn't shock half as hard as that coil wire haha!
I am probably gonna end up getting a new ignition switch this week and hopefully that will solve the issue.

 

Check to make sure that there's a ground between your engine block and the cab, because my truck did that one time right after I got it. My truck was missing that ground, but its primary symptom was that the starter would run away, making me pull a battery cable. Once I grounded the cab to the engine, (which is where my battery negative cable goes) the truck never exhibited any of those symptoms again going on three years...

 

There's an entire thread here dedicated strictly to highlighting the bad starter relays that are out there. We're encouraged to post up store names and part numbers of the failed units so we can keep track of which ones have the best and worst reliability record.
Be good for you to put your info up there too.

Oddly enough, your new one might be bad too. But we'll give it the benefit of the doubt until you pull the Brown wire to see if it still runs on.

Still could be the starter relay/solenoid. The new one might be cranking the starter just fine, but has shorted between the Brown wire connection.
But hey, at least it's still cranking the engine! Lots of reports of failed units either within a few starts, or right out of the box. It's a very sad state of affairs.

Now that's an interesting clue. Not sure what it means, and will have to study the lighting circuit diagrams to see what's up with that.
Do you also have an oil pressure gauge? Or just the light?

Paul

 

With a red legend lens oil (low pressure warning) light coming on with 1st position of the key (IMO it only has the one OEM oil pressure/monitoring/low pressure warning system. And that light coming on and going then off is a circuit ck of the system. I do believe anyway.

 

I GOT IT TO WORK!

I loosened up the positive side of the solenoid and played with the wires and everything works perfect now! I did buy a new ignition switch and it still did the same thing till I played with the solenoid. Thank you everyone for your help!