My truck has a junkyard Duraspark ignition setup on it that's been in service for about a year. I bought it from someone else so I don't know what year the FE truck it came from but I know it came from a Dentside truck. I'm using the "blue" grommet module. I decided to replace the module with a Motorcraft unit and keep the junkyard module for a spare. To my surprise the ignition would not fire with a brand new module. I went to the parts store and got a new module, tested it there, put it on the truck and still no ignition. I put the junkyard module back on and the truck fires right up.

Both of the "new" modules are for a 1978 Ford F250 with a 460 and both are the "blue" grommet units.

I've checked the connectors and all wire colors are in the same place.

I'm stumped.

Is there some difference between "blue" grommet modules?

 

Have you had your old box check, get it checked, about any parts house can do it, if it checks bad someone has changed a wire. Be the way all the blue modules will interchange I'm using one from a 76 F350 with a 460 on my 300

 

New modules have been known to be bad. And sometimes a bad one will test "good" Similar to your situation, I had a module go bad. Put the spare on to get it running. Bad module tested good. But, would not get the truck to run.

 

I'll have to have my old working box checked. I tried two new boxes and neither would work on my truck. I was scratching my head, surely I wouldn't get two new, non-working boxes. I didn't think there should be any difference between one blue grommet box and the other.

 

The 3 step scenario of a failing DuraSpark ignition module:

1) Module overheats, engine dies. Module cools down, engine restarts almost at once.

2) Module overheats, engine dies. Module cools down, engine restarts in a hour or so.

3) Sooner or later...usually sooner, the module overheats, BURNS OUT. Now the engine will not restart.

Engine heat, especially on V8's, is the mortal enemy of these modules that are located on the left fender inner apron, directly across from the V8's red hot exhaust manifold.

If replacing, use some washer to space the module further away from the apron, the more airflow, the better.

Taking the module to an auto parts store to be tested: Will test OK unless it has burned out.

1U2Z-12A199-AA (replaced D6AZ-12A199-A & B ~ D8VZ-12A199-A ~ D9VZ-12A199-A) .. DuraSpark Ignition Module - blue grommet (Motorcraft DY-893) / Available from Ford & auto parts stores.

Applications: Myriad 1976/90's FoMoCo vehicles.

D4PZ-12A112-A .. Stator aka magnetic pick-up coil (Motorcraft DU-1A) / Available from Ford & auto parts stores.

Applications: ALL 1974/79 V8 FoMoCo vehicles except 1979 LTD/Grand Marquis 351W with EEC (on board computer).

Most Ford techs replaced both of these parts, because the stator can suffer the same symptoms as the module.

 

I was just trying to replace a working junkyard box with a brand new one for peace of mind. I was trying to replace it before it failed.

 

Now if my faded old memory isn't too far off the mark then the Blue Duraspark has a better advance curve than the Red Duraspark.
But either should plug right into your distributor and go. Unless someone changed the wiring in the distributor.

 

That's what's strange. I have a blue grommet module from the junkyard running on the truck now. I tried to replace it with two different new modules and neither would fire in the truck. I took one of the new modules and tried it in a different vehicle and it worked.

 

The red grommet module (D7AZ-12A199-A) was only installed in some 1977/79 CA vehicles.

 

I'm going to take dissect the wiring and see what I can glean.

 

I've seen a lot of them on vehicles in Arizona.
The fact that the Red grommet modules were intended for smog vehicles in Kalifornia explains the difference in advance curves.

 

did you ever figure it out?

 

Factory blue modules have two circuits, a start retard circuit and a run circuit. The system runs on the retard circuit when the starter is engaged then swaps to the run circuit when you let the key fall back to run. Lots of aftermarket modules delete the start retard circuit and only have the single circuit inside.

It sounds like maybe who ever wired your truck has it running on the retard circuit, maybe the wires are crossed? On the two wire plug that supplies power to the box, one is Start and the other is Run. You can try swapping them.