86 F-250, 460, 4 speed, 4x4, carb., Duraspark ignition system. Sometimes I have spark, sometimes I don't. I check it at the top of the distributor at the coil wire. What I know about ignition systems is not much. Any suggestions will be appreciated. Best, CB

 

i am having similar problem. will be listening in

 

Quote:

Originally Posted by Charlie Bravo

Sometimes I have spark, sometimes I don't.

This is a classic warning symptom (EDIT: and is generally heat-related) that the DSII
module (gray box on the LH wheel cover) is failing and is on its way out. Many auto parts
stores can test the things if you remove and bring them in.

 

Most of the time it happens after sitting over night. It won't have spark until I leave the hood open and have the automatic trickle charger on it for a few hours. I know this is strange. I'm wondering if it doesn't have enough power to run the electronics when the starter is turning. Mechanically, I can do anything to this vehicle. When it comes to electronics, I is dumb. Best, CB

 

Quote:

Originally Posted by Charlie Bravo

I'm wondering if it doesn't have enough power to run the electronics when the starter is turning.

You can test this with a multimeter... when you seem to not have power at the
coil, see if you also don't have power at the ds2 box (though I forget exactly
what wires to test, hope others chime in). Could also be the ignition ground
circuit needs attention. The 460s had some weird "features" that I'm not
entirely familiar with, hope others chime in, I shall ping somebody for help.

 

C.B.

A follow-on to ctubutis' post.
The red wire provides power in start and a signal to the DSII to retard the timing while starting.
The white wire provides power while running.

My personal thinking (maybe way off base) on your situation is that you might have an issue with the pickup in your distributor.
Perhaps IT has a bad ground, or a chafed wire.
if the Orange or Purple wire is frayed and shorting to ground, signal won't trigger the DSII box to spark.
If you have dew or condensation in the morning maybe leaving the hood open to charge the battery is allowing these wires going to, or inside the dizzy to dry out and the system goes back to working as it should.
At the least I would unplug all the harness connections, clean up the pins and apply some dielectric silicone to keep the connections free from oxidation and moisture.

Just my two cents, and no guarantee that it will help, but it is something to look at.

 

The coil and the DS2 module all use the same ground point, it is also the wire clamping screw under the dist cap, the wiring harness goes from 3 wire to 2 wires at this point also.

 

JimsRebel,

I know the DS2 grounds inside the distributor. I'm saying that if the reluctor pickup wire's insulation is compromised moisture could ground it. The trigger signal is not strong.

 

I, also, am going to ck into all that, Jim and Jim. I am making progress. I found an unconnected ground...so I now have good current into the cab. No ign yet, however.

 

First thing I'd do is have the Duraspark-II module tested. These can be tested at most auto part stores.

A failing DS-II module can have these symptoms you describe.

The quick connect, connectors are supposed to be packed with white lithium grease at both the module and the distributor connectors.

On Truck side of the harness, and orignal Motorcraft Modules... The wire colors are as follows...

Red/Light Blue stripe: Start circut.
White/Light Blue Hash: Run circut.
Red/Light Green stripe: Coil Wire Hot. (7 volts aproximate in Run, 12 volts aprox. in Start mode, with starter disconnected)
Light Green/Yellow stripe: Tach (Coil ground signal to DS-II module and Tach in dash)
Black: Ignition Ground
Purple: Stator
Orange: Stator

On Aftermarket And Replacement Motorcraft Modules the Red and white wires are reversed...

Red: Run
White: Start

All other colors are the same as above.

 

Thanks. I'll report when I check it out. Best, CB