ok i have a 74 f250 camper special with a 390 i replaced the points condensor rotor and cap on the distributor and ran like a champ for a couple of hours then it started to stutter that night. figured it could wait till after work the next day when i got home, but on my way home it got worse and it got to the point of where it would idle fine but as soon as you touch the throttle it would stutter could go anywhere stuck 5 miles from town i thought maybe it was the fuel filter so i by-passed it and nothing then it would start at all, (didnt want to fire at all and plenty of fuel) since then i have replace a fuel hose that i found was leaking new coil and plugs (wires are only 2 months old and carb was rebuilt at the same time) i get a spark when the plugs are out of the engine but when they are in there is no fire at all. So my question is where do i go from here?

 

Double check the points... they are reknown for loosening and going out of adjustment.

Personally, I recommend ditching the points and going with a Pertronix unit. Dead nuts reliable.. I run them in all my older vehicles and have had zero failures.

 

Can you please clarify what you mean by "out of the engine?" The spark plugs ground by threading into the cylinder head; they cannot fire at all if free-standing. You are saying the opposite of what makes sense.

Please explain exactly what you're doing to check for spark, under what exact conditions spark is present, and under what exact conditions spark is absent. The goal here is for us to spend more time troubleshooting your truck's problem and less time troubleshooting what you are actually trying to say.

 

lol sorry i dont own an in-line spark tester to i have the plug out of the engine with the plug wire attached and ground the plug and turn the engine over to make sure i have spark crude but it works

as far as put a different ignition system in it i have one sitting on the shelf but i want to get the bug out of the engine before i put it on

an added point i by-passed the balist resistor that is before the coil and it wanted to fire ran for a sec real rough had to order the new one which is not the same as the one on the engine idk if gthey changed from ceramic to just a wire style of if that is like the rest of the rest and jerry-rigged for it to work

 

Thank you for the clarification. If you have spark using this method, then what has lead you to believe the system acts any differently with the plug installed?

You've lost me here. Why have you all of a sudden moved toward bypassing the ballast resistor? You should not do this. Just because you got it to temporarily run this way does not mean you need to all of a sudden order parts. Unless your wiring harness has been modified, you already have the correct ballast resistor bundled into the dash harness.

You still haven't made it clear to me why you think you don't have spark, and why you're heading down the path you're headed. Your engine won't start, so you've checked for spark (as you should) and you had spark, so I'm not sure why you're chopping up the ignition system now. Everything you've told me up to the point where the truck failed to start completely sounds like a fuel issue. Have you checked for fuel?

 

the wiring harness has be altered along with most of the wiring on this truck (but that is a diffrent story for a diffrent time) the ballst resistor on the truck is ceramic and the part that i have seen over and over again is a wire style.

ok back to the spark issue. ok so i have the spark plug out and it fire like it should but when i replace the plug back into the engine there is no fire the engine just turns over i have done this with every plug to make sure the plug and wire are working and i am getting spark but every time i put them back into the engine it acts like there is no spark (new plugs mind you) and yet im getting fuel and the time is dead nuts on where i set it

so yes to answer to your question i have check for fuel (its there) checked timing (#1 cylinder at top at 0) checked for spark (have it) put a test light through the ignition system to double check power and the test light flickers when its between the resistor and coil where the power should be steady correct?

 

Okay, thank you for the clarification. You are correct; the resistor wire is much more common because it is the factory setup.

If the spark plug fires when it's out of the engine but grounded to the block, then you have to assume that it's firing just the same when physically threaded into the cylinder head. Nothing electrical changes when you do this.

Assuming you are connecting the test light between the negative terminal of the coil and ground, it should BLINK as you are seeing, NOT stay steady. You are seeing the correct behavior.

I assume that the spark was nice and blue, and you checked for fuel by making sure fuel sprays onto the venturi's when you pull back the throttle?

Make sure your points gap is correct using a feeler gauge, and that the points, condensor, and negative coil wire (which connects to the points) are all properly seated. Even if the timing is correct and you're seeing spark, it may not be hitting at the right time. Make sure the breakerplate in the distributor hasn't separated from the baseplate, and that the small braided wire connecting the two inside the distributor is still in good shape.

 

the only questionable thing i seen in the ignition system was that the test like would blink if you put it on the wire between the coil and resistor (positive wire) instead of stay steady

the first spark was blue the rest were more a red or orange (new coil and plug wires only a couple months old might not have been the best ground when i tested the spark), and yes i have check fuel hit the throttle and gas is being sprayed into carb

and i had someone else install the new parts in the distributor im pretty sure they did verything right they have worked on many vechiles of mine in the past this one just seems to be stumping us both

 

This is still expected, it's just not as bright of a blinking action if you do it using the negative terminal. The reason you still see blinking at the positive terminal is because there is a voltage drop across the ballast resistor upstream of the coil with the points closed (test light dim), and no voltage drop across the ballast with the points open (test light bright). The points open and close as the engine cranks. Again, this is all expected.

The reason the blinking action is brighter when done at the negative terminal is because the negative terminal is grounded with the points closed (test light off), and pulled to battery voltage when the points are open (test light full brightness). This is much easier to discern and therefore recommended over the positive terminal.

Again, everything you are seeing with regard to blinking is completely normal.

All I can say is, check again. If everything was fine, then obviously the truck would start. The truck is not starting, so something is not fine. You don't know that everything is put together correctly until you go through each item in the distributor that I have listed. We can't be of much further help until you eliminate these variables.

 

just so i know what is the correct gap for the points gap?

 

.017" is the point gap.
A couple of things to check, okay, three things to check. First, make sure the distributor is tight and hasn't moved, changing the timing. Second check the distributor for worn shaft bushings. Pop the dist. cap off and remove the rotor. Try to move the shaft side to side. Dont try to rotate it because it will move in a rotational plane (centrifugal advance) you're looking for excess play, side to side.
Third, and this is/was a very common problem with Ford points and condenser distributor. Look at the dist. plate. This is the plate that the points and condenser mount to. It is actually two separate pieces that are held together with and pivot on a plastic rivet. This is for the vacuum advance. This rivet breaks and allows the plate that the points mount on to move around throwing off both the timing and the point gap setting.
It's easy to replace without removing the distributor.

 

ya i have looked at the plates before when i was having issues with it (thats why i had the points and condesonr changed) and everything was good (was afraid the advance was sticking) but i will check the gap to make sure that it is right sadly wont be able to get to it till tues

 

I realize you are focused on the electrical issues, but I'm not convinced a fuel problem hasn't been ruled out (especially if you have spark). Perhaps I've missed something but when you say you checked for fuel and "it's there", what does that mean? It's where? In the tank? At the carb? In the carb?

 

old Coyote- there is around half a tank of gas in it (droped the tank to fix a leaky hose) have pressure at the carb (new fuel pump not even a month old) and when i hit the throttle i do see a steady stream of fuel going into the carb and when i change the plug i did notice there was fuel on the plugs (this is after trying to start it for half a day) and this is why im at ignition fuel isnt being ignited (btw lets not assume that all people asking for help are idiots i may not be a mech but i know my way around an engine and that was the first thing i checked and how i found the leaky hose)

ok back to the things i was asked to check i put the old balist resistor back on everything in the dist is tight, gap is good, braid wire is good condition not frad or broken and still has good connections, and bushing seem fine very min movent maybe 1/32 if even that dist is tight and hasnt moved (marked it before when i thought i was having timing issues turn out the condenser or points were bad ran like a champ for 2 hours lol) and i did try it with the new resistor and still no fire at all still turns over just fine just wont fire.

 

D2PZ-12151-A V8 point plate is composed of upper/lower plates held together by nylon bushings. The bushings/crack/disintigrate, the upper plate separates from the lower.

It only takes one defective bushing to cause a problem. Prior to 1972, there were two individual plates.