My 17 year old son a has a 1970 F100 Ranger with a stock 1978 351w, 2bbl. in it. The problem seems to be that when he is driving it will just die, No warning, it will just cut off. Pull the truck over and it fires right back up. The other thing is it doesn't do it everytime I drove the truck yesterday for about a 1/2 hour and it ran fine. Now my thinking is that its electrical and not fuel related, it runs way to smooth for it to be fuel related and it fires right back up after it dies. I had also pulled a couple of plugs and they looked perfect. Now the distributor is the old points style that was converted with that kit that Petronix sells. I do not now how long ago that it was installed because the previous owner did it, and he had the truck restored back in the early 90's. Has anybody ever had a issue with these Petronix conversion kits or seen a problem similar to this? The poor kid is really bummed out, he really loves that old truck, so if anybody can help us out it will be greatly appreciated.

Thanks,
JD

 

It's possible for any kind of electronics to fail; some of Ford's own duraspark ignition modules had a bad reputation for failure. The symptoms are a little different though. They did not die immediately, but they sometimes would come back to life after they're allowed to cool off for a while.

If you're suspecting the Pertronix, maybe you can get some parts to revert it back to points to see if the engine runs more reliably. Of course, for problems like these, you can only know for sure that it didn't work if it fails again, but you'll never know for sure that it's been fixed.

 

Yes I am leaning towards a distibutor issue. I found another points style distributor that I think we will throw in and see if that makes a difference. Its frustrating since it only occurs off and on.

 

You can probably eliminate the coil , they usually need to cool for 15 minutes .

I always though all 12v coils were 12v , but most need a resistor or they run too hot .

I have been playing with N Ford tractors for the last few years and have had coil issues come up on 12v and or pertronix conversions .

Usually when a conversion is made , the coil gets straight 12v's .

Since your truck had points it probably didn't need a resistor unless the coil has been changed .

Do you have a good ground strap from the motor to the body ?

Here again , most of the tractor problems trace back to a bad ground or corroded terminal .

 

That's a good point; most ignition systems of that era have the 12 volts applied directly to the coil only during cranking. Then when you stop cranking, the coil gets its 12 volts through a resistor; I guess that's 9 volts typical. That's controlled by the ignition switch, and it may be another place you can check for bad contacts.

 

Just my $0.02, but I wouldn't be so quick to discount a fuel delivery issue.

There could be some debris inside the fuel tank which is getting caught at the pickup, causing the almost instantaneous shut off of the truck. Once the vacuum of that pump goes away (truck stops running), it would fall away from the pick up and allow the truck to start again. Seeing as it was restored by someone else, its kind of a crap shoot as to whether the previous owner replaced, reconditioned, or simply did nothing with the old fuel tank. And it has been about 10+ years since the resto was done, so something might have gotten in there over the years.

Is he noticing any other symptoms at the time the truck dies? Loss of headlights? Stereo?

 

No, no loss of 12v at all. You know I never thought of that. We did recently replace the fuel pump and filter but we did that after the problem started.I may need to pull that tank.

 

if it's starving for fuel and it dies you should be able to pump it and feel it start to run when it get a squirt, then it dies...(bucking as you pump) and when the carb is empty because of an obstruction in the tank it would take some cranking on the starter to get the fuel back into the carb...

like when you run out of gas and you put a few gallons in the tank.. to wont just fire up you have to crank it over some to get the fuel back to the carb

So when it dies and you go to re-start does it fire right up or does it take some cranking to get it to go.... ???

 

My bet would be a bad distributor ground. Or if the truck has a tach hooked up to it, look at the tach wire where it passes thru the firewall. Loose the distributor ground and it'll die instantly. Actually it's kind of confusing, ground the distributor ground and the ignition will quit. There's also a short ground wire inside the distributor, if that's loose, it'll do the same thing.

 

Other symptoms of partially clogged fuel filter is loss of power, or stumbling when trying to apply more power, but seemingly normal idle. The fuel flow increases when you're trying to apply more power, like accelerating, and that's when obstructions in the fuel line are most noticeable. And as mentioned, you get temporary relief by stopping for a while as the clog drops off of the filter when flow stops. But it clogs again when you get going again.

 

Guys I want to thank all of you for your responses in trying to figure out the issue with my sons truck. Well we FINALLY figured it out, it was the ignition switch. Of all things I would have never suspected the ignition switch would cause a intermittant problem like that. I purchased a new switch and plan on installing it tomorrow. I guess now my question is are they hard to remove? Any tricks to popping it apart? I have never had to replaced one before. And again thanks for all of the help.

 

The switch itself unscrews from the dash via the outer ring of the face, it's got three notches you can use to help unscrew it. To put your tumbler in the new switch (if you want to keep the same keys) you need nothing more than a big paper clip inserted into that hole in the front of the tumbler, next to the key slot. Insert paper clip, turn the key and the tumbler will come out by pulling on the key.

 

I think it's a black box that is located on top of the column... there is a rod that pushes into it from the tumbler... take the two bolts that hold the column up to the dash and drop it down and you will see the box, it's got the rod and a bunch of wires going into it..