83 F150 - 302 ignition spark question
 

With the durospark 2 system on my 83 f150 302, should the spark be hotter when starting (cranking) the truck or when the engine is running? Or should they be the same?

Hotter when starting the coil is fed a Full 12V during start and during run it is reduced through the ballast resistor to about 8V

That is what I thought, but needed to verify. I get turned around troubleshooting electrical issues sometimes.

I still have what I consider a weak spark at the coil when cranking the engine over. It is a new coil. To test the spark, I am connecting a new spark plug wire and spark plug to the coil and grounding the plug out and having a friend crank the engine over. The plug is sparking plenty of times as it should, it is just not fat and blue. The plug is gapped properly also. I have connected my volt meter to the positive wire of the saddle connector going to the coil and it is getting full 12v when we crank the engine over. What else can be causing this weak spark? Are these saddle connectors known for causing poor spark? What else should I check?

Thanks for the help.

Check your connections at the connectors for the module and on the coil.
Barring that you may have weak coil.

Cap, rotor, and plugs wires gain resistance as they age, which can cause the problem you are describing. Also, bad engine block ground connections are a thing to check. Measure coil resistance, should be about 1.5 ohms primary and 6-9K secondary.

Check battery/charging system as well.

He is connecting directly to the coil to test with a new plug wire. So "Cap, rotor, and plugs wires" are not the issue.

Likely he just got a bad coil even more likely if it is an off shore part.

If you want to "see" a bigger better spark at the plug just keep increasing the plug gap .050, .060, .070
The plug gap is directly related to the amount of energy the coil outputs.
While the coil is a step up transformer, the energy release point is determined by the plug gap.
If you hold the coil wire close to ground it will jump the gap, then slowly increase the gap until the spark quits. I don't do this anymore as I don't like to get shocked, now I just get the wife to hold the coil wire }>
Jim

If i find my new china made coil is no good, what brand should i get and from where? The new one i have i got from oreillys.

ill try widening the gap to .05 and see what happens.

The thing to remember the larger the gap the more resistance the system has and spark will try and find the easiest path to ground.
On the old HEI systems set to .060+ plug gap would burn holes thru the rotor or coils.
The large plug gap also puts a big strain on the IGN module and it can put a shorter life on it.
Just something to keep in mind.
Dave ----

Test the resistance in the coil - primary - 1 - 1.3 Ohms.....secondary - 8K - 11K Ohms.

New coil - Primary coil resistance 1.7 ohms
Secondary 8.5k ohms

Should i get another new coil? If so what brand?

Yes, that coil is pooched. Can't help you on brand names.....MotorCraft? I know the MSD blaster has a good reputation....from what I've seen, but they are pricey...~ 50 bucks I think.

Now, there's a reason the coil's primaries went south.....,usually it's because the ballast resistor gave up the ghost. But it could be that its old, too.

To test the resistor wire: Key ON engine OFF measure the voltage from the coil's (+) wire to a good clean ground. What are you reading?

7.5 to 8 volts with key in on position. 12 volts when cranking the engine over. I think the resistor is working.

Yessuh, the resistor circuit and bypass circuit are working fine. Time to replace an old, worn out coil.

Before you test the coil touch the 2 leads together, if the meter reads .3 ohms then you would subtract the .3 from 1.7 = 1.4 ohms.
Not all meters are real accurate in these low ranges.
Jim