I need more information pertaining to my truck not shutting off once or twice in the past. Also I seem to MAYBE have a parasitic voltage draw, AND may truck will suddenly not start !!! I am beginning to wonder if all these issues are related and caused by the same problem/s...............
I know sometimes the alternator can continue to work and cause a voltage spike that keeps the vehicle to run. I have a bigger amperage battery than stock. My grounds are 1 from intake to cab that maybe also connected to a circuit inside to something, 1 from engine block to battery . I think I had just installed a ground from battery to the radiator support or the body. This MAY have been when the problem of it not shutting happened !!! I have contacted Pertronix tech support & they have responded & I am currently waiting on them to respond to additional information I gave them.............
Any of you to notch gurus know anything what I need to do. I removed most of the fuses looking for the voltage drain & nothing seemed to be wrong, but I was told I need to look for a faulty ground which I am a little confused as how exactly to do this.......So now I am back to outside to check some wiring..........and reinstall the ground to the body & battery & maybe add one from cab to frame........... .............Wish Me Luck ~~~

 

I am so not qualified to give guru advice but still, my first thought is if you have a parasitic voltage draw with the engine off there should be a corresponding parasitic current draw. If that was true then you should be able to measure the current draw by lifting a battery lead and bridging the gap with a multi-meter, set on amps/current.
Unless there's been some additions to your truck, there is nothing in my old '72 250 that I can think of that should cause any non use draw.

A couple of other random thoughts;
If you had some sort of leakage / cell problem internally in the battery, that could mimic a parasitic draw. So, from a charged battery, again with the battery disconnected, the naturally occurring voltage loss of a lead acid battery over a few days or a week would be minimal, anything significant would indicate a battery problem.

Regarding the grounds, If two different points on the truck are not at the same ground level, then you would get a different voltage measurement from each of those points to the positive terminal of the battery, though the difference might be fairly small, or you could measure the continuity between the two ground points with the meter set on ohms.

 

I would not use a multimeter inline with battery cable and battery terminal to test amperage. Multimeters can handle very small amp loads that way. If there is a high amp draw you can blow a fuse in the multimeter or ruin your multimeter all together. When testing unknown amp loads you would be better off with a clamp on meter meant to read amp loads.

That said, keep the multimeter on the DC voltage setting, go ahead and disconnect postive battery cable, and put the multimeter inline. If you see 0 volts with key off nothing else turned on such as headlights, there is no draw. If you do see voltage, you can remove one fuse at a time on the fuse block and when the voltage goes back to zero you have found the circuit causing the draw. Also check for any extra wires that may have been connected to the positive battery terminal or on the battery side starter solenoid terminal and see if they are drawing power. If you have an aftermarket stereo it may have a very small draw for keep alive memory but it should be very small.

 

When you say the engine keeps running, do you mean running as normal and turning your key off has no effect or is it dieseling after shut-off and continues to fire but not very well and you are hearing a lot of spark knock when it happens?

 

This was my question.

If it keeps running normally, this could account for the parasitic draw you are experiencing. Something with your ignition switch and wiring could be faulty and cause it to act like you left the key on.

 

Since you started a new thread RTT, refresh our memories. What all has been done to the truck since you got it?
And even though I could be mixing you up with someone else, is this the truck that had an under-hood fire that you rewired?
If that was not you, is everything under the hood still stock?

and yes, please clarify the continuing to run aspect.

 

And also, please explain what you mean by sometimes the truck suddenly won’t start.
Is any of this discussed in another thread already?

 

New to the thread and truck
I think you are experiencing dieseling or run on
Caused mainly by too much ignition timing on an old, carbureted vehicle
Also, can be caused by a hot spot on a piston or valve
Like a piece of carbon that stays cherry red for a moment on the piston or valve
Your alternator has zero to do with the run on
It sure might be your draw though
How fast does the battery go dead?
Do you know how to do a negative draw test?

 

True enough about the multi-meter, though some have an higher amps setting, mine has a 400ma and a 10a setting, and I should have said that much as you did. My thought at the time was that any draw has to be pretty small to not be noticeable. Like say if a door switch was making just enough contact while supposed to be open (door closed) to create a draw but not enough to actually light the bulb. I'd be amazed if a non use (truck off) draw was pulling more than 10amps.

Interesting thought about measuring in-line set on DC. A multi-meter has a really high internal resistance (mega to giga ohms) which is why they don't short out when placed across negative and positive terminals, essentially no current draw. They were designed to measure voltage in parallel with the circuit. Used in-line set on DC, the meter leads are an extension of the battery cable but that high resistance would inhibit any current flow, so I guess the meter would be safe and no truck function would work, no current flow but any completed path to ground (leakage) would be like connecting the meter from the positive to the negative terminal so you should measure a voltage. I just never thought about it that way, which is why I went the measure a current draw route.

 

I never did the test , I went out and did do some much needed garage related chores ( organization ) .
Next day I got the worst case of the FLU I have ever had. I think I only had the flu 2 twice before, but anyway I hurt so bad my teeth hurt............chills for a day & aches for about 3............Almost well..........Oh I got a FLU shot...........did not go to Doc, but do not know what else it could have been............I had 103* temp 3 or 4 yrs ago well I think it went higher because I felt so bad i did not check it again & I do think it went higher.
This time I had worst chills & I honestly felt like I had fire coming out my nose........I think I may have hit 105* did not check dumb me
Any way , I have not checked my response from Pertronix yet about the Faulty Ground..........
I have said this before , " THIS SITE " helps me more than ya'll can imagine My life has constant mucho negativity that is beyond my control My truck is one of the few lasting pleasures I have
So , I will do my best to respond soon to all your much appreciated HELP
RANDOMLY..........truck would not stop running, not dieseling........I have a meter with high amp compatibility, have not thought it may be an amp problem but will certainly check.
The only fuse I have installed is the minuscule instrument fuse just because I could not get it out
I have the ignition fuse out but I THINK truck has started without it before, which I think is strange..............I have voltage at spark plug & I think at coil........
This info is from my troubleshooting several full moons ago, I took a break........
Anyway............my life actually is very slowly getting better, but will not be normal anytime soon..........if ever.........
Driving this truck is almost HEAVENLY.............I TOTALLY LUV COLUMN SHIFTING ,
So thank u all very, very MUCH............

 

If I understand correctly, the engine stays running as normal when your attempt to turn it off, that means something is keeping the coil energized so it continues to provide spark for the engine.

That could be an issue with the ignition switch itself or might be elsewhere in the harness. I'm not very familiar with the wiring harness in the pre 1975 trucks that used points style ignition. I'm curious if there's a bypass wire used during start up that bypasses the ballast resistor/resistance wire that feeds the coil when the key is in the run position.

Regardless, something it still providing power to the coil for it to continue running and I would start with testing the ignition switch to see if it's the culprit.

​​​​

 

Correct. Ford used a resistor wire in this case (pinkish/brown in color, but transitions to Red w/green stripe for coil power.
There is a Brown wire on the "I" terminal of the starter relay/solenoid on the fender. This is the bypass during START.
The location of the splice where those two wires joins will vary by vehicle model and year, but "usually" it's in the engine connector between the firewall and back of the engine. The two wires are molded into the one pin location so that, as far as the engine harness goes, there is only the one Red w/green wire to the coil positive. The coil negative gets the Black wire from the points.

There are often times when testing of this circuit simply involves disconnecting the little 90 degree push-on fitting on the Brown wire at the starter relay. If the relay is defective and sending power through the Brown wire, this would definitely keep the engine running.
When testing this wire, it's normal for it to be powered up coming from the other end, because it's literally joined at the hip with the resistor wire from the ignition switch. So with the key ON, you will see power on the Brown wire. Varying between about 6v and whatever system voltage is at the time, depending on the position of the points in the distributor. Which is why you never leave the key on for very long with the engine not running. As we all should know, but sometimes still forget!

If you can measure voltage on the "I" terminal at any time but during START, then the relay is defective and must be replaced. Hopefully with one that works... But that's a discussion for another time.

Paul

 

Truck only contentiously ran like this once or twice, BUT it has only had about 100 miles or less of driving other than driveway work.
I have an extra relay because I installed a Pertronix distributor & coil.and wanted to keep my resistor wire! Pertronix gave me some help & should have more advice for me, but have not checked my sources recently........
I think I may need a diode installed, or have a bad negative ground. I will do the test you suggested soon. I am not as well as I thought & have lots of other problems to deal with but I am doing better than I wuz............
you guys r GREAT.......... Thanx..........

P.S.-The alternator voltage spike I mentioned earlier was on a drag car & it does not pertain to my issue like I thought it did originally ! Maybe related slightly........

 

I would possibly swap back to a points distributor in your 71
Your Petronix module may be causing the problem
Your photo
Were you a Ford Asset student?

 

Thank-you 4 the advice !
I just now consulted with a PERTRONIX TECHNITION. He simplified some previous advice & new revelations ........ha
I feel better about my chances of FINALLY solving my LAST major obstacle mechanically related , body has plenty of issues left , but I am moving forward, thanx to all
I wish I was a FORD STUDENT!!!!!!!!!!!
I AM A BACKYARD - SHADE TREE - FORD STUDENT............LOL......
I have about 7 -10 ten test to perform. Too late to do them today..........but very soon, wish me luck............& ~~~ SUNSHINE ~~~